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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 14:58:38 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 14:58:38 -0700 |
| commit | e4cbce4d131753eca271d9d67f58c6377f27ad21 (patch) | |
| tree | e08e3c8836cd7b9f800e209131aed70897f5fe07 | |
| parent | b34133fec882d2717f2d61a2a010edd3422368c8 (diff) | |
| parent | 949bcb8135a96a6923e676646bd29cbe69e8350f (diff) | |
| download | linux-e4cbce4d131753eca271d9d67f58c6377f27ad21.tar.gz linux-e4cbce4d131753eca271d9d67f58c6377f27ad21.tar.bz2 linux-e4cbce4d131753eca271d9d67f58c6377f27ad21.zip | |
Merge tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- Improve uclamp performance by using a static key for the fast path
- Add the "sched_util_clamp_min_rt_default" sysctl, to optimize for
better power efficiency of RT tasks on battery powered devices.
(The default is to maximize performance & reduce RT latencies.)
- Improve utime and stime tracking accuracy, which had a fixed boundary
of error, which created larger and larger relative errors as the
values become larger. This is now replaced with more precise
arithmetics, using the new mul_u64_u64_div_u64() helper in math64.h.
- Improve the deadline scheduler, such as making it capacity aware
- Improve frequency-invariant scheduling
- Misc cleanups in energy/power aware scheduling
- Add sched_update_nr_running tracepoint to track changes to nr_running
- Documentation additions and updates
- Misc cleanups and smaller fixes
* tag 'sched-core-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (54 commits)
sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst
sched/doc: Document capacity aware scheduling
sched: Document arch_scale_*_capacity()
arm, arm64: Fix selection of CONFIG_SCHED_THERMAL_PRESSURE
Documentation/sysctl: Document uclamp sysctl knobs
sched/uclamp: Add a new sysctl to control RT default boost value
sched/uclamp: Fix a deadlock when enabling uclamp static key
sched: Remove duplicated tick_nohz_full_enabled() check
sched: Fix a typo in a comment
sched/uclamp: Remove unnecessary mutex_init()
arm, arm64: Select CONFIG_SCHED_THERMAL_PRESSURE
sched: Cleanup SCHED_THERMAL_PRESSURE kconfig entry
arch_topology, sched/core: Cleanup thermal pressure definition
trace/events/sched.h: fix duplicated word
linux/sched/mm.h: drop duplicated words in comments
smp: Fix a potential usage of stale nr_cpus
sched/fair: update_pick_idlest() Select group with lowest group_util when idle_cpus are equal
sched: nohz: stop passing around unused "ticks" parameter.
sched: Better document ttwu()
sched: Add a tracepoint to track rq->nr_running
...
48 files changed, 1521 insertions, 332 deletions
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst index 83acf5025488..55bf6b4de4ec 100644 --- a/Documentation/admin-guide/sysctl/kernel.rst +++ b/Documentation/admin-guide/sysctl/kernel.rst @@ -1062,6 +1062,60 @@ Enables/disables scheduler statistics. Enabling this feature incurs a small amount of overhead in the scheduler but is useful for debugging and performance tuning. +sched_util_clamp_min: +===================== + +Max allowed *minimum* utilization. + +Default value is 1024, which is the maximum possible value. + +It means that any requested uclamp.min value cannot be greater than +sched_util_clamp_min, i.e., it is restricted to the range +[0:sched_util_clamp_min]. + +sched_util_clamp_max: +===================== + +Max allowed *maximum* utilization. + +Default value is 1024, which is the maximum possible value. + +It means that any requested uclamp.max value cannot be greater than +sched_util_clamp_max, i.e., it is restricted to the range +[0:sched_util_clamp_max]. + +sched_util_clamp_min_rt_default: +================================ + +By default Linux is tuned for performance. Which means that RT tasks always run +at the highest frequency and most capable (highest capacity) CPU (in +heterogeneous systems). + +Uclamp achieves this by setting the requested uclamp.min of all RT tasks to +1024 by default, which effectively boosts the tasks to run at the highest +frequency and biases them to run on the biggest CPU. + +This knob allows admins to change the default behavior when uclamp is being +used. In battery powered devices particularly, running at the maximum +capacity and frequency will increase energy consumption and shorten the battery +life. + +This knob is only effective for RT tasks which the user hasn't modified their +requested uclamp.min value via sched_setattr() syscall. + +This knob will not escape the range constraint imposed by sched_util_clamp_min +defined above. + +For example if + + sched_util_clamp_min_rt_default = 800 + sched_util_clamp_min = 600 + +Then the boost will be clamped to 600 because 800 is outside of the permissible +range of [0:600]. This could happen for instance if a powersave mode will +restrict all boosts temporarily by modifying sched_util_clamp_min. As soon as +this restriction is lifted, the requested sched_util_clamp_min_rt_default +will take effect. seccomp ======= diff --git a/Documentation/scheduler/index.rst b/Documentation/scheduler/index.rst index 69074e5de9c4..88900aabdbf7 100644 --- a/Documentation/scheduler/index.rst +++ b/Documentation/scheduler/index.rst @@ -12,6 +12,7 @@ Linux Scheduler sched-deadline sched-design-CFS sched-domains + sched-capacity sched-energy sched-nice-design sched-rt-group diff --git a/Documentation/scheduler/sched-capacity.rst b/Documentation/scheduler/sched-capacity.rst new file mode 100644 index 000000000000..00bf0d011e2a --- /dev/null +++ b/Documentation/scheduler/sched-capacity.rst @@ -0,0 +1,439 @@ +========================= +Capacity Aware Scheduling +========================= + +1. CPU Capacity +=============== + +1.1 Introduction +---------------- + +Conventional, homogeneous SMP platforms are composed of purely identical +CPUs. Heterogeneous platforms on the other hand are composed of CPUs with +different performance characteristics - on such platforms, not all CPUs can be +considered equal. + +CPU capacity is a measure of the performance a CPU can reach, normalized against +the most performant CPU in the system. Heterogeneous systems are also called +asymmetric CPU capacity systems, as they contain CPUs of different capacities. + +Disparity in maximum attainable performance (IOW in maximum CPU capacity) stems +from two factors: + +- not all CPUs may have the same microarchitecture (µarch). +- with Dynamic Voltage and Frequency Scaling (DVFS), not all CPUs may be + physically able to attain the higher Operating Performance Points (OPP). + +Arm big.LITTLE systems are an example of both. The big CPUs are more +performance-oriented than the LITTLE ones (more pipeline stages, bigger caches, +smarter predictors, etc), and can usually reach higher OPPs than the LITTLE ones +can. + +CPU performance is usually expressed in Millions of Instructions Per Second +(MIPS), which can also be expressed as a given amount of instructions attainable +per Hz, leading to:: + + capacity(cpu) = work_per_hz(cpu) * max_freq(cpu) + +1.2 Scheduler terms +------------------- + +Two different capacity values are used within the scheduler. A CPU's +``capacity_orig`` is its maximum attainable capacity, i.e. its maximum +attainable performance level. A CPU's ``capacity`` is its ``capacity_orig`` to +which some loss of available performance (e.g. time spent handling IRQs) is +subtracted. + +Note that a CPU's ``capacity`` is solely intended to be used by the CFS class, +while ``capacity_orig`` is class-agnostic. The rest of this document will use +the term ``capacity`` interchangeably with ``capacity_orig`` for the sake of +brevity. + +1.3 Platform examples +--------------------- + +1.3.1 Identical OPPs +~~~~~~~~~~~~~~~~~~~~ + +Consider an hypothetical dual-core asymmetric CPU capacity system where + +- work_per_hz(CPU0) = W +- work_per_hz(CPU1) = W/2 +- all CPUs are running at the same fixed frequency + +By the above definition of capacity: + +- capacity(CPU0) = C +- capacity(CPU1) = C/2 + +To draw the parallel with Arm big.LITTLE, CPU0 would be a big while CPU1 would +be a LITTLE. + +With a workload that periodically does a fixed amount of work, you will get an +execution trace like so:: + + CPU0 work ^ + | ____ ____ ____ + | | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + + CPU1 work ^ + | _________ _________ ____ + | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + +CPU0 has the highest capacity in the system (C), and completes a fixed amount of +work W in T units of time. On the other hand, CPU1 has half the capacity of +CPU0, and thus only completes W/2 in T. + +1.3.2 Different max OPPs +~~~~~~~~~~~~~~~~~~~~~~~~ + +Usually, CPUs of different capacity values also have different maximum +OPPs. Consider the same CPUs as above (i.e. same work_per_hz()) with: + +- max_freq(CPU0) = F +- max_freq(CPU1) = 2/3 * F + +This yields: + +- capacity(CPU0) = C +- capacity(CPU1) = C/3 + +Executing the same workload as described in 1.3.1, which each CPU running at its +maximum frequency results in:: + + CPU0 work ^ + | ____ ____ ____ + | | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + + workload on CPU1 + CPU1 work ^ + | ______________ ______________ ____ + | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + +1.4 Representation caveat +------------------------- + +It should be noted that having a *single* value to represent differences in CPU +performance is somewhat of a contentious point. The relative performance +difference between two different µarchs could be X% on integer operations, Y% on +floating point operations, Z% on branches, and so on. Still, results using this +simple approach have been satisfactory for now. + +2. Task utilization +=================== + +2.1 Introduction +---------------- + +Capacity aware scheduling requires an expression of a task's requirements with +regards to CPU capacity. Each scheduler class can express this differently, and +while task utilization is specific to CFS, it is convenient to describe it here +in order to introduce more generic concepts. + +Task utilization is a percentage meant to represent the throughput requirements +of a task. A simple approximation of it is the task's duty cycle, i.e.:: + + task_util(p) = duty_cycle(p) + +On an SMP system with fixed frequencies, 100% utilization suggests the task is a +busy loop. Conversely, 10% utilization hints it is a small periodic task that +spends more time sleeping than executing. Variable CPU frequencies and +asymmetric CPU capacities complexify this somewhat; the following sections will +expand on these. + +2.2 Frequency invariance +------------------------ + +One issue that needs to be taken into account is that a workload's duty cycle is +directly impacted by the current OPP the CPU is running at. Consider running a +periodic workload at a given frequency F:: + + CPU work ^ + | ____ ____ ____ + | | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + +This yields duty_cycle(p) == 25%. + +Now, consider running the *same* workload at frequency F/2:: + + CPU work ^ + | _________ _________ ____ + | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + +This yields duty_cycle(p) == 50%, despite the task having the exact same +behaviour (i.e. executing the same amount of work) in both executions. + +The task utilization signal can be made frequency invariant using the following +formula:: + + task_util_freq_inv(p) = duty_cycle(p) * (curr_frequency(cpu) / max_frequency(cpu)) + +Applying this formula to the two examples above yields a frequency invariant +task utilization of 25%. + +2.3 CPU invariance +------------------ + +CPU capacity has a similar effect on task utilization in that running an +identical workload on CPUs of different capacity values will yield different +duty cycles. + +Consider the system described in 1.3.2., i.e.:: + +- capacity(CPU0) = C +- capacity(CPU1) = C/3 + +Executing a given periodic workload on each CPU at their maximum frequency would +result in:: + + CPU0 work ^ + | ____ ____ ____ + | | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + + CPU1 work ^ + | ______________ ______________ ____ + | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + +IOW, + +- duty_cycle(p) == 25% if p runs on CPU0 at its maximum frequency +- duty_cycle(p) == 75% if p runs on CPU1 at its maximum frequency + +The task utilization signal can be made CPU invariant using the following +formula:: + + task_util_cpu_inv(p) = duty_cycle(p) * (capacity(cpu) / max_capacity) + +with ``max_capacity`` being the highest CPU capacity value in the +system. Applying this formula to the above example above yields a CPU +invariant task utilization of 25%. + +2.4 Invariant task utilization +------------------------------ + +Both frequency and CPU invariance need to be applied to task utilization in +order to obtain a truly invariant signal. The pseudo-formula for a task +utilization that is both CPU and frequency invariant is thus, for a given +task p:: + + curr_frequency(cpu) capacity(cpu) + task_util_inv(p) = duty_cycle(p) * ------------------- * ------------- + max_frequency(cpu) max_capacity + +In other words, invariant task utilization describes the behaviour of a task as +if it were running on the highest-capacity CPU in the system, running at its +maximum frequency. + +Any mention of task utilization in the following sections will imply its +invariant form. + +2.5 Utilization estimation +-------------------------- + +Without a crystal ball, task behaviour (and thus task utilization) cannot +accurately be predicted the moment a task first becomes runnable. The CFS class +maintains a handful of CPU and task signals based on the Per-Entity Load +Tracking (PELT) mechanism, one of those yielding an *average* utilization (as +opposed to instantaneous). + +This means that while the capacity aware scheduling criteria will be written +considering a "true" task utilization (using a crystal ball), the implementation +will only ever be able to use an estimator thereof. + +3. Capacity aware scheduling requirements +========================================= + +3.1 CPU capacity +---------------- + +Linux cannot currently figure out CPU capacity on its own, this information thus +needs to be handed to it. Architectures must define arch_scale_cpu_capacity() +for that purpose. + +The arm and arm64 architectures directly map this to the arch_topology driver +CPU scaling data, which is derived from the capacity-dmips-mhz CPU binding; see +Documentation/devicetree/bindings/arm/cpu-capacity.txt. + +3.2 Frequency invariance +------------------------ + +As stated in 2.2, capacity-aware scheduling requires a frequency-invariant task +utilization. Architectures must define arch_scale_freq_capacity(cpu) for that +purpose. + +Implementing this function requires figuring out at which frequency each CPU +have been running at. One way to implement this is to leverage hardware counters +whose increment rate scale with a CPU's current frequency (APERF/MPERF on x86, +AMU on arm64). Another is to directly hook into cpufreq frequency transitions, +when the kernel is aware of the switched-to frequency (also employed by +arm/arm64). + +4. Scheduler topology +===================== + +During the construction of the sched domains, the scheduler will figure out +whether the system exhibits asymmetric CPU capacities. Should that be the +case: + +- The sched_asym_cpucapacity static key will be enabled. +- The SD_ASYM_CPUCAPACITY flag will be set at the lowest sched_domain level that + spans all unique CPU capacity values. + +The sched_asym_cpucapacity static key is intended to guard sections of code that +cater to asymmetric CPU capacity systems. Do note however that said key is +*system-wide*. Imagine the following setup using cpusets:: + + capacity C/2 C + ________ ________ + / \ / \ + CPUs 0 1 2 3 4 5 6 7 + \__/ \______________/ + cpusets cs0 cs1 + +Which could be created via: + +.. code-block:: sh + + mkdir /sys/fs/cgroup/cpuset/cs0 + echo 0-1 > /sys/fs/cgroup/cpuset/cs0/cpuset.cpus + echo 0 > /sys/fs/cgroup/cpuset/cs0/cpuset.mems + + mkdir /sys/fs/cgroup/cpuset/cs1 + echo 2-7 > /sys/fs/cgroup/cpuset/cs1/cpuset.cpus + echo 0 > /sys/fs/cgroup/cpuset/cs1/cpuset.mems + + echo 0 > /sys/fs/cgroup/cpuset/cpuset.sched_load_balance + +Since there *is* CPU capacity asymmetry in the system, the +sched_asym_cpucapacity static key will be enabled. However, the sched_domain +hierarchy of CPUs 0-1 spans a single capacity value: SD_ASYM_CPUCAPACITY isn't +set in that hierarchy, it describes an SMP island and should be treated as such. + +Therefore, the 'canonical' pattern for protecting codepaths that cater to +asymmetric CPU capacities is to: + +- Check the sched_asym_cpucapacity static key +- If it is enabled, then also check for the presence of SD_ASYM_CPUCAPACITY in + the sched_domain hierarchy (if relevant, i.e. the codepath targets a specific + CPU or group thereof) + +5. Capacity aware scheduling implementation +=========================================== + +5.1 CFS +------- + +5.1.1 Capacity fitness +~~~~~~~~~~~~~~~~~~~~~~ + +The main capacity scheduling criterion of CFS is:: + + task_util(p) < capacity(task_cpu(p)) + +This is commonly called the capacity fitness criterion, i.e. CFS must ensure a +task "fits" on its CPU. If it is violated, the task will need to achieve more +work than what its CPU can provide: it will be CPU-bound. + +Furthermore, uclamp lets userspace specify a minimum and a maximum utilization +value for a task, either via sched_setattr() or via the cgroup interface (see +Documentation/admin-guide/cgroup-v2.rst). As its name imply, this can be used to +clamp task_util() in the previous criterion. + +5.1.2 Wakeup CPU selection +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +CFS task wakeup CPU selection follows the capacity fitness criterion described +above. On top of that, uclamp is used to clamp the task utilization values, +which lets userspace have more leverage over the CPU selection of CFS +tasks. IOW, CFS wakeup CPU selection searches for a CPU that satisfies:: + + clamp(task_util(p), task_uclamp_min(p), task_uclamp_max(p)) < capacity(cpu) + +By using uclamp, userspace can e.g. allow a busy loop (100% utilization) to run +on any CPU by giving it a low uclamp.max value. Conversely, it can force a small +periodic task (e.g. 10% utilization) to run on the highest-performance CPUs by +giving it a high uclamp.min value. + +.. note:: + + Wakeup CPU selection in CFS can be eclipsed by Energy Aware Scheduling + (EAS), which is described in Documentation/scheduling/sched-energy.rst. + +5.1.3 Load balancing +~~~~~~~~~~~~~~~~~~~~ + +A pathological case in the wakeup CPU selection occurs when a task rarely +sleeps, if at all - it thus rarely wakes up, if at all. Consider:: + + w == wakeup event + + capacity(CPU0) = C + capacity(CPU1) = C / 3 + + workload on CPU0 + CPU work ^ + | _________ _________ ____ + | | | | | | + +----+----+----+----+----+----+----+----+----+----+-> time + w w w + + workload on CPU1 + CPU work ^ + | ____________________________________________ + | | + +----+----+----+----+----+----+----+----+----+----+-> + w + +This workload should run on CPU0, but if the task either: + +- was improperly scheduled from the start (inaccurate initial + utilization estimation) +- was properly scheduled from the start, but suddenly needs more + processing power + +then it might become CPU-bound, IOW ``task_util(p) > capacity(task_cpu(p))``; +the CPU capacity scheduling criterion is violated, and there may not be any more +wakeup event to fix this up via wakeup CPU selection. + +Tasks that are in this situation are dubbed "misfit" tasks, and the mechanism +put in place to handle this shares the same name. Misfit task migration +leverages the CFS load balancer, more specifically the active load balance part +(which caters to migrating currently running tasks). When load balance happens, +a misfit active load balance will be triggered if a misfit task can be migrated +to a CPU with more capacity than its current one. + +5.2 RT +------ + +5.2.1 Wakeup CPU selection +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +RT task wakeup CPU selection searches for a CPU that satisfies:: + + task_uclamp_min(p) <= capacity(task_cpu(cpu)) + +while still following the usual priority constraints. If none of the candidate +CPUs can satisfy this capacity criterion, then strict priority based scheduling +is followed and CPU capacities are ignored. + +5.3 DL +------ + +5.3.1 Wakeup CPU selection +~~~~~~~~~~~~~~~~~~~~~~~~~~ + +DL task wakeup CPU selection searches for a CPU that satisfies:: + + task_bandwidth(p) < capacity(task_cpu(p)) + +while still respecting the usual bandwidth and deadline constraints. If +none of the candidate CPUs can satisfy this capacity criterion, then the +task will remain on its current CPU. diff --git a/Documentation/scheduler/sched-energy.rst b/Documentation/scheduler/sched-energy.rst index 9580c57a52bc..78f850778982 100644 --- a/Documentation/scheduler/sched-energy.rst +++ b/Documentation/scheduler/sched-energy.rst @@ -331,16 +331,8 @@ asymmetric CPU topologies for now. This requirement is checked at run-time by looking for the presence of the SD_ASYM_CPUCAPACITY flag when the scheduling domains are built. -The flag is set/cleared automatically by the scheduler topology code whenever -there are CPUs with different capacities in a root domain. The capacities of -CPUs are provided by arch-specific code through the arch_scale_cpu_capacity() -callback. As an example, arm and arm64 share an implementation of this callback -which uses a combination of CPUFreq data and device-tree bindings to compute the -capacity of CPUs (see drivers/base/arch_topology.c for more details). - -So, in order to use EAS on your platform your architecture must implement the -arch_scale_cpu_capacity() callback, and some of the CPUs must have a lower -capacity than others. +See Documentation/sched/sched-capacity.rst for requirements to be met for this +flag to be set in the sched_domain hierarchy. Please note that EAS is not fundamentally incompatible with SMP, but no significant savings on SMP platforms have been observed yet. This restriction diff --git a/arch/arm/include/asm/topology.h b/arch/arm/include/asm/topology.h index 435aba289fc5..e0593cf095d0 100644 --- a/arch/arm/include/asm/topology.h +++ b/arch/arm/include/asm/topology.h @@ -16,8 +16,9 @@ /* Enable topology flag updates */ #define arch_update_cpu_topology topology_update_cpu_topology -/* Replace task scheduler's default thermal pressure retrieve API */ +/* Replace task scheduler's default thermal pressure API */ #define arch_scale_thermal_pressure topology_get_thermal_pressure +#define arch_set_thermal_pressure topology_set_thermal_pressure #else diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h index 0cc835ddfcd1..e042f6527981 100644 --- a/arch/arm64/include/asm/topology.h +++ b/arch/arm64/include/asm/topology.h @@ -34,8 +34,9 @@ void topology_scale_freq_tick(void); /* Enable topology flag updates */ #define arch_update_cpu_topology topology_update_cpu_topology -/* Replace task scheduler's default thermal pressure retrieve API */ +/* Replace task scheduler's default thermal pressure API */ #define arch_scale_thermal_pressure topology_get_thermal_pressure +#define arch_set_thermal_pressure topology_set_thermal_pressure #include <asm-generic/topology.h> diff --git a/arch/x86/include/asm/div64.h b/arch/x86/include/asm/div64.h index 9b8cb50768c2..b8f1dc0761e4 100644 --- a/arch/x86/include/asm/div64.h +++ b/arch/x86/include/asm/div64.h @@ -74,16 +74,26 @@ static inline u64 mul_u32_u32(u32 a, u32 b) #else # include <asm-generic/div64.h> -static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div) +/* + * Will generate an #DE when the result doesn't fit u64, could fix with an + * __ex_table[] entry when it becomes an issue. + */ +static inline u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div) { u64 q; asm ("mulq %2; divq %3" : "=a" (q) - : "a" (a), "rm" ((u64)mul), "rm" ((u64)div) + : "a" (a), "rm" (mul), "rm" (div) : "rdx"); return q; } +#define mul_u64_u64_div_u64 mul_u64_u64_div_u64 + +static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 div) +{ + return mul_u64_u64_div_u64(a, mul, div); +} #define mul_u64_u32_div mul_u64_u32_div #endif /* CONFIG_X86_32 */ diff --git a/arch/x86/include/asm/topology.h b/arch/x86/include/asm/topology.h index 79d8d5496330..f4234575f3fd 100644 --- a/arch/x86/include/asm/topology.h +++ b/arch/x86/include/asm/topology.h @@ -193,7 +193,7 @@ static inline void sched_clear_itmt_support(void) } #endif /* CONFIG_SCHED_MC_PRIO */ -#ifdef CONFIG_SMP +#if defined(CONFIG_SMP) && defined(CONFIG_X86_64) #include <asm/cpufeature.h> DECLARE_STATIC_KEY_FALSE(arch_scale_freq_key); diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index ffbd9a3d78d8..518ac6bf752e 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -56,6 +56,7 @@ #include <linux/cpuidle.h> #include <linux/numa.h> #include <linux/pgtable.h> +#include <linux/overflow.h> #include <asm/acpi.h> #include <asm/desc.h> @@ -1777,6 +1778,7 @@ void native_play_dead(void) #endif +#ifdef CONFIG_X86_64 /* * APERF/MPERF frequency ratio computation. * @@ -1975,6 +1977,7 @@ static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq) static bool intel_set_max_freq_ratio(void) { u64 base_freq, turbo_freq; + u64 turbo_ratio; if (slv_set_max_freq_ratio(&base_freq, &turbo_freq)) goto out; @@ -2000,15 +2003,23 @@ out: /* * Some hypervisors advertise X86_FEATURE_APERFMPERF * but then fill all MSR's with zeroes. + * Some CPUs have turbo boost but don't declare any turbo ratio + * in MSR_TURBO_RATIO_LIMIT. */ - if (!base_freq) { - pr_debug("Couldn't determine cpu base frequency, necessary for scale-invariant accounting.\n"); + if (!base_freq || !turbo_freq) { + pr_debug("Couldn't determine cpu base or turbo frequency, necessary for scale-invariant accounting.\n"); return false; } - arch_turbo_freq_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, - base_freq); + turbo_ratio = div_u64(turbo_freq * SCHED_CAPACITY_SCALE, base_freq); + if (!turbo_ratio) { + pr_debug("Non-zero turbo and base frequencies led to a 0 ratio.\n"); + return false; + } + + arch_turbo_freq_ratio = turbo_ratio; arch_set_max_freq_ratio(turbo_disabled()); + return true; } @@ -2048,11 +2059,19 @@ static void init_freq_invariance(bool secondary) } } +static void disable_freq_invariance_workfn(struct work_struct *work) +{ + static_branch_disable(&arch_scale_freq_key); +} + +static DECLARE_WORK(disable_freq_invariance_work, + disable_freq_invariance_workfn); + DEFINE_PER_CPU(unsigned long, arch_freq_scale) = SCHED_CAPACITY_SCALE; void arch_scale_freq_tick(void) { - u64 freq_scale; + u64 freq_scale = SCHED_CAPACITY_SCALE; u64 aperf, mperf; u64 acnt, mcnt; @@ -2064,19 +2083,32 @@ void arch_scale_freq_tick(void) acnt = aperf - this_cpu_read(arch_prev_aperf); mcnt = mperf - this_cpu_read(arch_prev_mperf); - if (!mcnt) - return; this_cpu_write(arch_prev_aperf, aperf); this_cpu_write(arch_prev_mperf, mperf); - acnt <<= 2*SCHED_CAPACITY_SHIFT; - mcnt *= arch_max_freq_ratio; + if (check_shl_overflow(acnt, 2*SCHED_CAPACITY_SHIFT, &acnt)) + goto error; + + if (check_mul_overflow(mcnt, arch_max_freq_ratio, &mcnt) || !mcnt) + goto error; freq_scale = div64_u64(acnt, mcnt); + if (!freq_scale) + goto error; if (freq_scale > SCHED_CAPACITY_SCALE) freq_scale = SCHED_CAPACITY_SCALE; this_cpu_write(arch_freq_scale, freq_scale); + return; + +error: + pr_warn("Scheduler frequency invariance went wobbly, disabling!\n"); + schedule_work(&disable_freq_invariance_work); +} +#else +static inline void init_freq_invariance(bool secondary) +{ } +#endif /* CONFIG_X86_64 */ diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index 4d0a0038b476..75f72d684294 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -54,6 +54,17 @@ void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity) per_cpu(cpu_scale, cpu) = capacity; } +DEFINE_PER_CPU(unsigned long, thermal_pressure); + +void topology_set_thermal_pressure(const struct cpumask *cpus, + unsigned long th_pressure) +{ + int cpu; + + for_each_cpu(cpu, cpus) + WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure); +} + static ssize_t cpu_capacity_show(struct device *dev, struct device_attribute *attr, char *buf) diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c index da6510af1221..449466f71040 100644 --- a/drivers/pci/pci-driver.c +++ b/drivers/pci/pci-driver.c @@ -12,6 +12,7 @@ #include <linux/string.h> #include <linux/slab.h> #include <linux/sched.h> +#include <linux/sched/isolation.h> #include <linux/cpu.h> #include <linux/pm_runtime.h> #include <linux/suspend.h> @@ -333,6 +334,7 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev, const struct pci_device_id *id) { int error, node, cpu; + int hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ; struct drv_dev_and_id ddi = { drv, dev, id }; /* @@ -353,7 +355,8 @@ static int pci_call_probe(struct pci_driver *drv, struct pci_dev *dev, pci_physfn_is_probed(dev)) cpu = nr_cpu_ids; else - cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask); + cpu = cpumask_any_and(cpumask_of_node(node), + housekeeping_cpumask(hk_flags)); if (cpu < nr_cpu_ids) error = work_on_cpu(cpu, local_pci_probe, &ddi); diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 052e0f05a984..de8493cc3082 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -109,12 +109,31 @@ #endif /* - * Align to a 32 byte boundary equal to the - * alignment gcc 4.5 uses for a struct + * GCC 4.5 and later have a 32 bytes section alignment for structures. + * Except GCC 4.9, that feels the need to align on 64 bytes. */ +#if __GNUC__ == 4 && __GNUC_MINOR__ == 9 +#define STRUCT_ALIGNMENT 64 +#else #define STRUCT_ALIGNMENT 32 +#endif #define STRUCT_ALIGN() . = ALIGN(STRUCT_ALIGNMENT) +/* + * The order of the sched class addresses are important, as they are + * used to determine the order of the priority of each sched class in + * relation to each other. + */ +#define SCHED_DATA \ + STRUCT_ALIGN(); \ + __begin_sched_classes = .; \ + *(__idle_sched_class) \ + *(__fair_sched_class) \ + *(__rt_sched_class) \ + *(__dl_sched_class) \ + *(__stop_sched_class) \ + __end_sched_classes = .; + /* The actual configuration determine if the init/exit sections * are handled as text/data or they can be discarded (which * often happens at runtime) @@ -389,6 +408,7 @@ .rodata : AT(ADDR(.rodata) - LOAD_OFFSET) { \ __start_rodata = .; \ *(.rodata) *(.rodata.*) \ + SCHED_DATA \ RO_AFTER_INIT_DATA /* Read only after init */ \ . = ALIGN(8); \ __start___tracepoints_ptrs = .; \ diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h index 0566cb3314ef..69b1dabe39dc 100644 --- a/include/linux/arch_topology.h +++ b/include/linux/arch_topology.h @@ -39,8 +39,8 @@ static inline unsigned long topology_get_thermal_pressure(int cpu) return per_cpu(thermal_pressure, cpu); } -void arch_set_thermal_pressure(struct cpumask *cpus, - unsigned long th_pressure); +void topology_set_thermal_pressure(const struct cpumask *cpus, + unsigned long th_pressure); struct cpu_topology { int thread_id; diff --git a/include/linux/math64.h b/include/linux/math64.h index 11a267413e8e..d097119419e6 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -263,6 +263,8 @@ static inline u64 mul_u64_u32_div(u64 a, u32 mul, u32 divisor) } #endif /* mul_u64_u32_div */ +u64 mul_u64_u64_div_u64(u64 a, u64 mul, u64 div); + #define DIV64_U64_ROUND_UP(ll, d) \ ({ u64 _tmp = (d); div64_u64((ll) + _tmp - 1, _tmp); }) diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h index 4b7258495a04..b95f3211566a 100644 --- a/include/linux/psi_types.h +++ b/include/linux/psi_types.h @@ -153,9 +153,10 @@ struct psi_group { unsigned long avg[NR_PSI_STATES - 1][3]; /* Monitor work control */ - atomic_t poll_scheduled; - struct kthread_worker __rcu *poll_kworker; - struct kthread_delayed_work poll_work; + struct task_struct __rcu *poll_task; + struct timer_list poll_timer; + wait_queue_head_t poll_wait; + atomic_t poll_wakeup; /* Protects data used by the monitor */ struct mutex trigger_lock; diff --git a/include/linux/sched.h b/include/linux/sched.h index 060e9214c8b5..6d6683b48c2a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -155,24 +155,24 @@ struct task_group; * * for (;;) { * set_current_state(TASK_UNINTERRUPTIBLE); - * if (!need_sleep) - * break; + * if (CONDITION) + * break; * * schedule(); * } * __set_current_state(TASK_RUNNING); * * If the caller does not need such serialisation (because, for instance, the - * condition test and condition change and wakeup are under the same lock) then + * CONDITION test and condition change and wakeup are under the same lock) then * use __set_current_state(). * * The above is typically ordered against the wakeup, which does: * - * need_sleep = false; + * CONDITION = 1; * wake_up_state(p, TASK_UNINTERRUPTIBLE); * - * where wake_up_state() executes a full memory barrier before accessing the - * task state. + * where wake_up_state()/try_to_wake_up() executes a full memory barrier before + * accessing p->state. * * Wakeup will do: if (@state & p->state) p->state = TASK_RUNNING, that is, * once it observes the TASK_UNINTERRUPTIBLE store the waking CPU can issue a @@ -375,7 +375,7 @@ struct util_est { * For cfs_rq, they are the aggregated values of all runnable and blocked * sched_entities. * - * The load/runnable/util_avg doesn't direcly factor frequency scaling and CPU + * The load/runnable/util_avg doesn't directly factor frequency scaling and CPU * capacity scaling. The scaling is done through the rq_clock_pelt that is used * for computing those signals (see update_rq_clock_pelt()) * @@ -687,9 +687,15 @@ struct task_struct { struct sched_dl_entity dl; #ifdef CONFIG_UCLAMP_TASK - /* Clamp values requested for a scheduling entity */ + /* + * Clamp values requested for a scheduling entity. + * Must be updated with task_rq_lock() held. + */ struct uclamp_se uclamp_req[UCLAMP_CNT]; - /* Effective clamp values used for a scheduling entity */ + /* + * Effective clamp values used for a scheduling entity. + * Must be updated with task_rq_lock() held. + */ struct uclamp_se uclamp[UCLAMP_CNT]; #endif @@ -2039,6 +2045,7 @@ const struct sched_avg *sched_trace_rq_avg_dl(struct rq *rq); const struct sched_avg *sched_trace_rq_avg_irq(struct rq *rq); int sched_trace_rq_cpu(struct rq *rq); +int sched_trace_rq_nr_running(struct rq *rq); const struct cpumask *sched_trace_rd_span(struct root_domain *rd); diff --git a/include/linux/sched/isolation.h b/include/linux/sched/isolation.h index 0fbcbacd1b29..cc9f393e2a70 100644 --- a/include/linux/sched/isolation.h +++ b/include/linux/sched/isolation.h @@ -14,6 +14,7 @@ enum hk_flags { HK_FLAG_DOMAIN = (1 << 5), HK_FLAG_WQ = (1 << 6), HK_FLAG_MANAGED_IRQ = (1 << 7), + HK_FLAG_KTHREAD = (1 << 8), }; #ifdef CONFIG_CPU_ISOLATION diff --git a/include/linux/sched/loadavg.h b/include/linux/sched/loadavg.h index 4859bea47a7b..83ec54b65e79 100644 --- a/include/linux/sched/loadavg.h +++ b/include/linux/sched/loadavg.h @@ -43,6 +43,6 @@ extern unsigned long calc_load_n(unsigned long load, unsigned long exp, #define LOAD_INT(x) ((x) >> FSHIFT) #define LOAD_FRAC(x) LOAD_INT(((x) & (FIXED_1-1)) * 100) -extern void calc_global_load(unsigned long ticks); +extern void calc_global_load(void); #endif /* _LINUX_SCHED_LOADAVG_H */ diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h index 480a4d1b7dd8..6be66f52a2ad 100644 --- a/include/linux/sched/mm.h +++ b/include/linux/sched/mm.h @@ -23,7 +23,7 @@ extern struct mm_struct *mm_alloc(void); * will still exist later on and mmget_not_zero() has to be used before * accessing it. * - * This is a preferred way to to pin @mm for a longer/unbounded amount + * This is a preferred way to pin @mm for a longer/unbounded amount * of time. * * Use mmdrop() to release the reference acquired by mmgrab(). @@ -49,8 +49,6 @@ static inline void mmdrop(struct mm_struct *mm) __mmdrop(mm); } -void mmdrop(struct mm_struct *mm); - /* * This has to be called after a get_task_mm()/mmget_not_zero() * followed by taking the mmap_lock for writing before modifying the @@ -234,7 +232,7 @@ static inline unsigned int memalloc_noio_save(void) * @flags: Flags to restore. * * Ends the implicit GFP_NOIO scope started by memalloc_noio_save function. - * Always make sure that that the given flags is the return value from the + * Always make sure that the given flags is the return value from the * pairing memalloc_noio_save call. */ static inline void memalloc_noio_restore(unsigned int flags) @@ -265,7 +263,7 @@ static inline unsigned int memalloc_nofs_save(void) * @flags: Flags to restore. * * Ends the implicit GFP_NOFS scope started by memalloc_nofs_save function. - * Always make sure that that the given flags is the return value from the + * Always make sure that the given flags is the return value from the * pairing memalloc_nofs_save call. */ static inline void memalloc_nofs_restore(unsigned int flags) diff --git a/include/linux/sched/sysctl.h b/include/linux/sched/sysctl.h index 660ac49f2b53..3c31ba88aca5 100644 --- a/include/linux/sched/sysctl.h +++ b/include/linux/sched/sysctl.h @@ -61,9 +61,13 @@ int sched_proc_update_handler(struct ctl_table *table, int write, extern unsigned int sysctl_sched_rt_period; extern int sysctl_sched_rt_runtime; +extern unsigned int sysctl_sched_dl_period_max; +extern unsigned int sysctl_sched_dl_period_min; + #ifdef CONFIG_UCLAMP_TASK extern unsigned int sysctl_sched_uclamp_util_min; extern unsigned int sysctl_sched_uclamp_util_max; +extern unsigned int sysctl_sched_uclamp_util_min_rt_default; #endif #ifdef CONFIG_CFS_BANDWIDTH diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index 1301077f9c24..27b4fa454c80 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -55,6 +55,7 @@ extern asmlinkage void schedule_tail(struct task_struct *prev); extern void init_idle(struct task_struct *idle, int cpu); extern int sched_fork(unsigned long clone_flags, struct task_struct *p); +extern void sched_post_fork(struct task_struct *p); extern void sched_dead(struct task_struct *p); void __noreturn do_task_dead(void); diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index fb11091129b3..820511289857 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -217,6 +217,16 @@ static inline bool cpus_share_cache(int this_cpu, int that_cpu) #endif /* !CONFIG_SMP */ #ifndef arch_scale_cpu_capacity +/** + * arch_scale_cpu_capacity - get the capacity scale factor of a given CPU. + * @cpu: the CPU in question. + * + * Return: the CPU scale factor normalized against SCHED_CAPACITY_SCALE, i.e. + * + * max_perf(cpu) + * ----------------------------- * SCHED_CAPACITY_SCALE + * max(max_perf(c) : c \in CPUs) + */ static __always_inline unsigned long arch_scale_cpu_capacity(int cpu) { @@ -232,6 +242,13 @@ unsigned long arch_scale_thermal_pressure(int cpu) } #endif +#ifndef arch_set_thermal_pressure +static __always_inline +void arch_set_thermal_pressure(const struct cpumask *cpus, + unsigned long th_pressure) +{ } +#endif + static inline int task_node(const struct task_struct *p) { return cpu_to_node(task_cpu(p)); diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h index ed168b0e2c53..fec25b9cfbaf 100644 --- a/include/trace/events/sched.h +++ b/include/trace/events/sched.h @@ -91,7 +91,7 @@ DEFINE_EVENT(sched_wakeup_template, sched_waking, /* * Tracepoint called when the task is actually woken; p->state == TASK_RUNNNG. - * It it not always called from the waking context. + * It is not always called from the waking context. */ DEFINE_EVENT(sched_wakeup_template, sched_wakeup, TP_PROTO(struct task_struct *p), @@ -634,6 +634,18 @@ DECLARE_TRACE(sched_overutilized_tp, TP_PROTO(struct root_domain *rd, bool overutilized), TP_ARGS(rd, overutilized)); +DECLARE_TRACE(sched_util_est_cfs_tp, + TP_PROTO(struct cfs_rq *cfs_rq), + TP_ARGS(cfs_rq)); + +DECLARE_TRACE(sched_util_est_se_tp, + TP_PROTO(struct sched_entity *se), + TP_ARGS(se)); + +DECLARE_TRACE(sched_update_nr_running_tp, + TP_PROTO(struct rq *rq, int change), + TP_ARGS(rq, change)); + #endif /* _TRACE_SCHED_H */ /* This part must be outside protection */ diff --git a/init/Kconfig b/init/Kconfig index 0498af567f70..9f7f249dab43 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -492,8 +492,23 @@ config HAVE_SCHED_AVG_IRQ depends on SMP config SCHED_THERMAL_PRESSURE - bool "Enable periodic averaging of thermal pressure" + bool + default y if ARM && ARM_CPU_TOPOLOGY + default y if ARM64 depends on SMP + depends on CPU_FREQ_THERMAL + help + Select this option to enable thermal pressure accounting in the + scheduler. Thermal pressure is the value conveyed to the scheduler + that reflects the reduction in CPU compute capacity resulted from + thermal throttling. Thermal throttling occurs when the performance of + a CPU is capped due to high operating temperatures. + + If selected, the scheduler will be able to balance tasks accordingly, + i.e. put less load on throttled CPUs than on non/less throttled ones. + + This requires the architecture to implement + arch_set_thermal_pressure() and arch_get_thermal_pressure(). config BSD_PROCESS_ACCT bool "BSD Process Accounting" diff --git a/kernel/fork.c b/kernel/fork.c index 0cc3d9cd6cc2..2a8e7287a558 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2302,6 +2302,7 @@ static __latent_entropy struct task_struct *copy_process( write_unlock_irq(&tasklist_lock); proc_fork_connector(p); + sched_post_fork(p); cgroup_post_fork(p, args); perf_event_fork(p); diff --git a/kernel/kthread.c b/kernel/kthread.c index 132f84a5fde3..1d9e2fdfd67a 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -27,6 +27,7 @@ #include <linux/ptrace.h> #include <linux/uaccess.h> #include <linux/numa.h> +#include <linux/sched/isolation.h> #include <trace/events/sched.h> @@ -383,7 +384,8 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data), * The kernel thread should not inherit these properties. */ sched_setscheduler_nocheck(task, SCHED_NORMAL, ¶m); - set_cpus_allowed_ptr(task, cpu_all_mask); + set_cpus_allowed_ptr(task, + housekeeping_cpumask(HK_FLAG_KTHREAD)); } kfree(create); return task; @@ -608,7 +610,7 @@ int kthreadd(void *unused) /* Setup a clean context for our children to inherit. */ set_task_comm(tsk, "kthreadd"); ignore_signals(tsk); - set_cpus_allowed_ptr(tsk, cpu_all_mask); + set_cpus_allowed_ptr(tsk, housekeeping_cpumask(HK_FLAG_KTHREAD)); set_mems_allowed(node_states[N_MEMORY]); current->flags |= PF_NOFREEZE; diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 2142c6767682..4a0e7b449b88 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -6,6 +6,10 @@ * * Copyright (C) 1991-2002 Linus Torvalds */ +#define CREATE_TRACE_POINTS +#include <trace/events/sched.h> +#undef CREATE_TRACE_POINTS + #include "sched.h" #include <linux/nospec.h> @@ -23,9 +27,6 @@ #include "pelt.h" #include "smp.h" -#define CREATE_TRACE_POINTS -#include <trace/events/sched.h> - /* * Export tracepoints that act as a bare tracehook (ie: have no trace event * associated with them) to allow external modules to probe them. @@ -36,6 +37,9 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_dl_tp); EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_irq_tp); EXPORT_TRACEPOINT_SYMBOL_GPL(pelt_se_tp); EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp); +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp); +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp); +EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp); DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); @@ -75,6 +79,100 @@ __read_mostly int scheduler_running; */ int sysctl_sched_rt_runtime = 950000; + +/* + * Serialization rules: + * + * Lock order: + * + * p->pi_lock + * rq->lock + * hrtimer_cpu_base->lock (hrtimer_start() for bandwidth controls) + * + * rq1->lock + * rq2->lock where: rq1 < rq2 + * + * Regular state: + * + * Normal scheduling state is serialized by rq->lock. __schedule() takes the + * local CPU's rq->lock, it optionally removes the task from the runqueue and + * always looks at the local rq data structures to find the most elegible task + * to run next. + * + * Task enqueue is also under rq->lock, possibly taken from another CPU. + * Wakeups from another LLC domain might use an IPI to transfer the enqueue to + * the local CPU to avoid bouncing the runqueue state around [ see + * ttwu_queue_wakelist() ] + * + * Task wakeup, specifically wakeups that involve migration, are horribly + * complicated to avoid having to take two rq->locks. + * + * Special state: + * + * System-calls and anything external will use task_rq_lock() which acquires + * both p->pi_lock and rq->lock. As a consequence the state they change is + * stable while holding either lock: + * + * - sched_setaffinity()/ + * set_cpus_allowed_ptr(): p->cpus_ptr, p->nr_cpus_allowed + * - set_user_nice(): p->se.load, p->*prio + * - __sched_setscheduler(): p->sched_class, p->policy, p->*prio, + * p->se.load, p->rt_priority, + * p->dl.dl_{runtime, deadline, period, flags, bw, density} + * - sched_setnuma(): p->numa_preferred_nid + * - sched_move_task()/ + * cpu_cgroup_fork(): p->sched_task_group + * - uclamp_update_active() p->uclamp* + * + * p->state <- TASK_*: + * + * is changed locklessly using set_current_state(), __set_current_state() or + * set_special_state(), see their respective comments, or by + * try_to_wake_up(). This latter uses p->pi_lock to serialize against + * concurrent self. + * + * p->on_rq <- { 0, 1 = TASK_ON_RQ_QUEUED, 2 = TASK_ON_RQ_MIGRATING }: + * + * is set by activate_task() and cleared by deactivate_task(), under + * rq->lock. Non-zero indicates the task is runnable, the special + * ON_RQ_MIGRATING state is used for migration without holding both + * rq->locks. It indicates task_cpu() is not stable, see task_rq_lock(). + * + * p->on_cpu <- { 0, 1 }: + * + * is set by prepare_task() and cleared by finish_task() such that it will be + * set before p is scheduled-in and cleared after p is scheduled-out, both + * under rq->lock. Non-zero indicates the task is running on its CPU. + * + * [ The astute reader will observe that it is possible for two tasks on one + * CPU to have ->on_cpu = 1 at the same time. ] + * + * task_cpu(p): is changed by set_task_cpu(), the rules are: + * + * - Don't call set_task_cpu() on a blocked task: + * + * We don't care what CPU we're not running on, this simplifies hotplug, + * the CPU assignment of blocked tasks isn't required to be valid. + * + * - for try_to_wake_up(), called under p->pi_lock: + * + * This allows try_to_wake_up() to only take one rq->lock, see its comment. + * + * - for migration called under rq->lock: + * [ see task_on_rq_migrating() in task_rq_lock() ] + * + * o move_queued_task() + * o detach_task() + * + * - for migration called under double_rq_lock(): + * + * o __migrate_swap_task() + * o push_rt_task() / pull_rt_task() + * o push_dl_task() / pull_dl_task() + * o dl_task_offline_migration() + * + */ + /* * __task_rq_lock - lock the rq @p resides on. */ @@ -791,9 +889,46 @@ unsigned int sysctl_sched_uclamp_util_min = SCHED_CAPACITY_SCALE; /* Max allowed maximum utilization */ unsigned int sysctl_sched_uclamp_util_max = SCHED_CAPACITY_SCALE; +/* + * By default RT tasks run at the maximum performance point/capacity of the + * system. Uclamp enforces this by always setting UCLAMP_MIN of RT tasks to + * SCHED_CAPACITY_SCALE. + * + * This knob allows admins to change the default behavior when uclamp is being + * used. In battery powered devices, particularly, running at the maximum + * capacity and frequency will increase energy consumption and shorten the + * battery life. + * + * This knob only affects RT tasks that their uclamp_se->user_defined == false. + * + * This knob will not override the system default sched_util_clamp_min defined + * above. + */ +unsigned int sysctl_sched_uclamp_util_min_rt_default = SCHED_CAPACITY_SCALE; + /* All clamps are required to be less or equal than these values */ static struct uclamp_se uclamp_default[UCLAMP_CNT]; +/* + * This static key is used to reduce the uclamp overhead in the fast path. It + * primarily disables the call to uclamp_rq_{inc, dec}() in + * enqueue/dequeue_task(). + * + * This allows users to continue to enable uclamp in their kernel config with + * minimum uclamp overhead in the fast path. + * + * As soon as userspace modifies any of the uclamp knobs, the static key is + * enabled, since we have an actual users that make use of uclamp + * functionality. + * + * The knobs that would enable this static key are: + * + * * A task modifying its uclamp value with sched_setattr(). + * * An admin modifying the sysctl_sched_uclamp_{min, max} via procfs. + * * An admin modifying the cgroup cpu.uclamp.{min, max} + */ +DEFINE_STATIC_KEY_FALSE(sched_uclamp_used); + /* Integer rounded range for each bucket */ #define UCLAMP_BUCKET_DELTA DIV_ROUND_CLOSEST(SCHED_CAPACITY_SCALE, UCLAMP_BUCKETS) @@ -873,6 +1008,64 @@ unsigned int uclamp_rq_max_value(struct rq *rq, enum uclamp_id clamp_id, return uclamp_idle_value(rq, clamp_id, clamp_value); } +static void __uclamp_update_util_min_rt_default(struct task_struct *p) +{ + unsigned int default_util_min; + struct uclamp_se *uc_se; + + lockdep_assert_held(&p->pi_lock); + + uc_se = &p->uclamp_req[UCLAMP_MIN]; + + /* Only sync if user didn't override the default */ + if (uc_se->user_defined) + return; + + default_util_min = sysctl_sched_uclamp_util_min_rt_default; + uclamp_se_set(uc_se, default_util_min, false); +} + +static void uclamp_update_util_min_rt_default(struct task_struct *p) +{ + struct rq_flags rf; + struct rq *rq; + + if (!rt_task(p)) + return; + + /* Protect updates to p->uclamp_* */ + rq = task_rq_lock(p, &rf); + __uclamp_update_util_min_rt_default(p); + task_rq_unlock(rq, p, &rf); +} + +static void uclamp_sync_util_min_rt_default(void) +{ + struct task_struct *g, *p; + + /* + * copy_process() sysctl_uclamp + * uclamp_min_rt = X; + * write_lock(&tasklist_lock) read_lock(&tasklist_lock) + * // link thread smp_mb__after_spinlock() + * write_unlock(&tasklist_lock) read_unlock(&tasklist_lock); + * sched_post_fork() for_each_process_thread() + * __uclamp_sync_rt() __uclamp_sync_rt() + * + * Ensures that either sched_post_fork() will observe the new + * uclamp_min_rt or for_each_process_thread() will observe the new + * task. + */ + read_lock(&tasklist_lock); + smp_mb__after_spinlock(); + read_unlock(&tasklist_lock); + + rcu_read_lock(); + for_each_process_thread(g, p) + uclamp_update_util_min_rt_default(p); + rcu_read_unlock(); +} + static inline struct uclamp_se uclamp_tg_restrict(struct task_struct *p, enum uclamp_id clamp_id) { @@ -990,10 +1183,38 @@ static inline void uclamp_rq_dec_id(struct rq *rq, struct task_struct *p, lockdep_assert_held(&rq->lock); + /* + * If sched_uclamp_used was enabled after task @p was enqueued, + * we could end up with unbalanced call to uclamp_rq_dec_id(). + * + * In this case the uc_se->active flag should be false since no uclamp + * accounting was performed at enqueue time and we can just return + * here. + * + * Need to be careful of the following enqeueue/dequeue ordering + * problem too + * + * enqueue(taskA) + * // sched_uclamp_used gets enabled + * enqueue(taskB) + * dequeue(taskA) + * // Must not decrement bukcet->tasks here + * dequeue(taskB) + * + * where we could end up with stale data in uc_se and + * bucket[uc_se->bucket_id]. + * + * The following check here eliminates the possibility of such race. + */ + if (unlikely(!uc_se->active)) + return; + bucket = &uc_rq->bucket[uc_se->bucket_id]; + SCHED_WARN_ON(!bucket->tasks); if (likely(bucket->tasks)) bucket->tasks--; + uc_se->active = false; /* @@ -1021,6 +1242,15 @@ static inline void uclamp_rq_inc(struct rq *rq, struct task_struct *p) { enum uclamp_id clamp_id; + /* + * Avoid any overhead until uclamp is actually used by the userspace. + * + * The condition is constructed such that a NOP is generated when + * sched_uclamp_used is disabled. + */ + if (!static_branch_unlikely(&sched_uclamp_used)) + return; + if (unlikely(!p->sched_class->uclamp_enabled)) return; @@ -1036,6 +1266,15 @@ static inline void uclamp_rq_dec(struct rq *rq, struct task_struct *p) { enum uclamp_id clamp_id; + /* + * Avoid any overhead until uclamp is actually used by the userspace. + * + * The condition is constructed such that a NOP is generated when + * sched_uclamp_used is disabled. + */ + if (!static_branch_unlikely(&sched_uclamp_used)) + return; + if (unlikely(!p->sched_class->uclamp_enabled)) return; @@ -1114,12 +1353,13 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { bool update_root_tg = false; - int old_min, old_max; + int old_min, old_max, old_min_rt; int result; mutex_lock(&uclamp_mutex); old_min = sysctl_sched_uclamp_util_min; old_max = sysctl_sched_uclamp_util_max; + old_min_rt = sysctl_sched_uclamp_util_min_rt_default; result = proc_dointvec(table, write, buffer, lenp, ppos); if (result) @@ -1128,7 +1368,9 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, goto done; if (sysctl_sched_uclamp_util_min > sysctl_sched_uclamp_util_max || - sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE) { + sysctl_sched_uclamp_util_max > SCHED_CAPACITY_SCALE || + sysctl_sched_uclamp_util_min_rt_default > SCHED_CAPACITY_SCALE) { + result = -EINVAL; goto undo; } @@ -1144,8 +1386,15 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, update_root_tg = true; } - if (update_root_tg) + if (update_root_tg) { + static_branch_enable(&sched_uclamp_used); uclamp_update_root_tg(); + } + + if (old_min_rt != sysctl_sched_uclamp_util_min_rt_default) { + static_branch_enable(&sched_uclamp_used); + uclamp_sync_util_min_rt_default(); + } /* * We update all RUNNABLE tasks only when task groups are in use. @@ -1158,6 +1407,7 @@ int sysctl_sched_uclamp_handler(struct ctl_table *table, int write, undo: sysctl_sched_uclamp_util_min = old_min; sysctl_sched_uclamp_util_max = old_max; + sysctl_sched_uclamp_util_min_rt_default = old_min_rt; done: mutex_unlock(&uclamp_mutex); @@ -1180,6 +1430,15 @@ static int uclamp_validate(struct task_struct *p, if (upper_bound > SCHED_CAPACITY_SCALE) return -EINVAL; + /* + * We have valid uclamp attributes; make sure uclamp is enabled. + * + * We need to do that here, because enabling static branches is a + * blocking operation which obviously cannot be done while holding + * scheduler locks. + */ + static_branch_enable(&sched_uclamp_used); + return 0; } @@ -1194,17 +1453,20 @@ static void __setscheduler_uclamp(struct task_struct *p, */ for_each_clamp_id(clamp_id) { struct uclamp_se *uc_se = &p->uclamp_req[clamp_id]; - unsigned int clamp_value = uclamp_none(clamp_id); /* Keep using defined clamps across class changes */ if (uc_se->user_defined) continue; - /* By default, RT tasks always get 100% boost */ + /* + * RT by default have a 100% boost value that could be modified + * at runtime. + */ if (unlikely(rt_task(p) && clamp_id == UCLAMP_MIN)) - clamp_value = uclamp_none(UCLAMP_MAX); + __uclamp_update_util_min_rt_default(p); + else + uclamp_se_set(uc_se, uclamp_none(clamp_id), false); - uclamp_se_set(uc_se, clamp_value, false); } if (likely(!(attr->sched_flags & SCHED_FLAG_UTIL_CLAMP))) @@ -1225,6 +1487,10 @@ static void uclamp_fork(struct task_struct *p) { enum uclamp_id clamp_id; + /* + * We don't need to hold task_rq_lock() when updating p->uclamp_* here + * as the task is still at its early fork stages. + */ for_each_clamp_id(clamp_id) p->uclamp[clamp_id].active = false; @@ -1237,19 +1503,33 @@ static void uclamp_fork(struct task_struct *p) } } +static void uclamp_post_fork(struct task_struct *p) +{ + uclamp_update_util_min_rt_default(p); +} + +static void __init init_uclamp_rq(struct rq *rq) +{ + enum uclamp_id clamp_id; + struct uclamp_rq *uc_rq = rq->uclamp; + + for_each_clamp_id(clamp_id) { + uc_rq[clamp_id] = (struct uclamp_rq) { + .value = uclamp_none(clamp_id) + }; + } + + rq->uclamp_flags = 0; +} + static void __init init_uclamp(void) { struct uclamp_se uc_max = {}; enum uclamp_id clamp_id; int cpu; - mutex_init(&uclamp_mutex); - - for_each_possible_cpu(cpu) { - memset(&cpu_rq(cpu)->uclamp, 0, - sizeof(struct uclamp_rq)*UCLAMP_CNT); - cpu_rq(cpu)->uclamp_flags = 0; - } + for_each_possible_cpu(cpu) + init_uclamp_rq(cpu_rq(cpu)); for_each_clamp_id(clamp_id) { uclamp_se_set(&init_task.uclamp_req[clamp_id], @@ -1278,6 +1558,7 @@ static inline int uclamp_validate(struct task_struct *p, static void __setscheduler_uclamp(struct task_struct *p, const struct sched_attr *attr) { } static inline void uclamp_fork(struct task_struct *p) { } +static inline void uclamp_post_fork(struct task_struct *p) { } static inline void init_uclamp(void) { } #endif /* CONFIG_UCLAMP_TASK */ @@ -1404,20 +1685,10 @@ static inline void check_class_changed(struct rq *rq, struct task_struct *p, void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) { - const struct sched_class *class; - - if (p->sched_class == rq->curr->sched_class) { + if (p->sched_class == rq->curr->sched_class) rq->curr->sched_class->check_preempt_curr(rq, p, flags); - } else { - for_each_class(class) { - if (class == rq->curr->sched_class) - break; - if (class == p->sched_class) { - resched_curr(rq); - break; - } - } - } + else if (p->sched_class > rq->curr->sched_class) + resched_curr(rq); /* * A queue event has occurred, and we're going to schedule. In @@ -1468,8 +1739,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, { lockdep_assert_held(&rq->lock); - WRITE_ONCE(p->on_rq, TASK_ON_RQ_MIGRATING); - dequeue_task(rq, p, DEQUEUE_NOCLOCK); + deactivate_task(rq, p, DEQUEUE_NOCLOCK); set_task_cpu(p, new_cpu); rq_unlock(rq, rf); @@ -1477,8 +1747,7 @@ static struct rq *move_queued_task(struct rq *rq, struct rq_flags *rf, rq_lock(rq, rf); BUG_ON(task_cpu(p) != new_cpu); - enqueue_task(rq, p, 0); - p->on_rq = TASK_ON_RQ_QUEUED; + activate_task(rq, p, 0); check_preempt_curr(rq, p, 0); return rq; @@ -2243,12 +2512,31 @@ ttwu_do_activate(struct rq *rq, struct task_struct *p, int wake_flags, } /* - * Called in case the task @p isn't fully descheduled from its runqueue, - * in this case we must do a remote wakeup. Its a 'light' wakeup though, - * since all we need to do is flip p->state to TASK_RUNNING, since - * the task is still ->on_rq. + * Consider @p being inside a wait loop: + * + * for (;;) { + * set_current_state(TASK_UNINTERRUPTIBLE); + * + * if (CONDITION) + * break; + * + * schedule(); + * } + * __set_current_state(TASK_RUNNING); + * + * between set_current_state() and schedule(). In this case @p is still + * runnable, so all that needs doing is change p->state back to TASK_RUNNING in + * an atomic manner. + * + * By taking task_rq(p)->lock we serialize against schedule(), if @p->on_rq + * then schedule() must still happen and p->state can be changed to + * TASK_RUNNING. Otherwise we lost the race, schedule() has happened, and we + * need to do a full wakeup with enqueue. + * + * Returns: %true when the wakeup is done, + * %false otherwise. */ -static int ttwu_remote(struct task_struct *p, int wake_flags) +static int ttwu_runnable(struct task_struct *p, int wake_flags) { struct rq_flags rf; struct rq *rq; @@ -2389,6 +2677,14 @@ static bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) return false; } + +#else /* !CONFIG_SMP */ + +static inline bool ttwu_queue_wakelist(struct task_struct *p, int cpu, int wake_flags) +{ + return false; +} + #endif /* CONFIG_SMP */ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) @@ -2396,10 +2692,8 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) struct rq *rq = cpu_rq(cpu); struct rq_flags rf; -#if defined(CONFIG_SMP) if (ttwu_queue_wakelist(p, cpu, wake_flags)) return; -#endif rq_lock(rq, &rf); update_rq_clock(rq); @@ -2455,8 +2749,8 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) * migration. However the means are completely different as there is no lock * chain to provide order. Instead we do: * - * 1) smp_store_release(X->on_cpu, 0) - * 2) smp_cond_load_acquire(!X->on_cpu) + * 1) smp_store_release(X->on_cpu, 0) -- finish_task() + * 2) smp_cond_load_acquire(!X->on_cpu) -- try_to_wake_up() * * Example: * @@ -2496,15 +2790,33 @@ static void ttwu_queue(struct task_struct *p, int cpu, int wake_flags) * @state: the mask of task states that can be woken * @wake_flags: wake modifier flags (WF_*) * - * If (@state & @p->state) @p->state = TASK_RUNNING. + * Conceptually does: + * + * If (@state & @p->state) @p->state = TASK_RUNNING. * * If the task was not queued/runnable, also place it back on a runqueue. * - * Atomic against schedule() which would dequeue a task, also see - * set_current_state(). + * This function is atomic against schedule() which would dequeue the task. + * + * It issues a full memory barrier before accessing @p->state, see the comment + * with set_current_state(). * - * This function executes a full memory barrier before accessing the task - * state; see set_current_state(). + * Uses p->pi_lock to serialize against concurrent wake-ups. + * + * Relies on p->pi_lock stabilizing: + * - p->sched_class + * - p->cpus_ptr + * - p->sched_task_group + * in order to do migration, see its use of select_task_rq()/set_task_cpu(). + * + * Tries really hard to only take one task_rq(p)->lock for performance. + * Takes rq->lock in: + * - ttwu_runnable() -- old rq, unavoidable, see comment there; + * - ttwu_queue() -- new rq, for enqueue of the task; + * - psi_ttwu_dequeue() -- much sadness :-( accounting will kill us. + * + * As a consequence we race really badly with just about everything. See the + * many memory barriers and their comments for details. * * Return: %true if @p->state changes (an actual wakeup was done), * %false otherwise. @@ -2520,7 +2832,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) /* * We're waking current, this means 'p->on_rq' and 'task_cpu(p) * == smp_processor_id()'. Together this means we can special - * case the whole 'p->on_rq && ttwu_remote()' case below + * case the whole 'p->on_rq && ttwu_runnable()' case below * without taking any locks. * * In particular: @@ -2541,8 +2853,8 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) /* * If we are going to wake up a thread waiting for CONDITION we * need to ensure that CONDITION=1 done by the caller can not be - * reordered with p->state check below. This pairs with mb() in - * set_current_state() the waiting thread does. + * reordered with p->state check below. This pairs with smp_store_mb() + * in set_current_state() that the waiting thread does. */ raw_spin_lock_irqsave(&p->pi_lock, flags); smp_mb__after_spinlock(); @@ -2577,7 +2889,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) * A similar smb_rmb() lives in try_invoke_on_locked_down_task(). */ smp_rmb(); - if (READ_ONCE(p->on_rq) && ttwu_remote(p, wake_flags)) + if (READ_ONCE(p->on_rq) && ttwu_runnable(p, wake_flags)) goto unlock; if (p->in_iowait) { @@ -2990,6 +3302,11 @@ int sched_fork(unsigned long clone_flags, struct task_struct *p) return 0; } +void sched_post_fork(struct task_struct *p) +{ + uclamp_post_fork(p); +} + unsigned long to_ratio(u64 period, u64 runtime) { if (runtime == RUNTIME_INF) @@ -3147,8 +3464,10 @@ static inline void prepare_task(struct task_struct *next) /* * Claim the task as running, we do this before switching to it * such that any running task will have this set. + * + * See the ttwu() WF_ON_CPU case and its ordering comment. */ - next->on_cpu = 1; + WRITE_ONCE(next->on_cpu, 1); #endif } @@ -3156,8 +3475,9 @@ static inline void finish_task(struct task_struct *prev) { #ifdef CONFIG_SMP /* - * After ->on_cpu is cleared, the task can be moved to a different CPU. - * We must ensure this doesn't happen until the switch is completely + * This must be the very last reference to @prev from this CPU. After + * p->on_cpu is cleared, the task can be moved to a different CPU. We + * must ensure this doesn't happen until the switch is completely * finished. * * In particular, the load of prev->state in finish_task_switch() must @@ -3656,17 +3976,6 @@ unsigned long long task_sched_runtime(struct task_struct *p) return ns; } -DEFINE_PER_CPU(unsigned long, thermal_pressure); - -void arch_set_thermal_pressure(struct cpumask *cpus, - unsigned long th_pressure) -{ - int cpu; - - for_each_cpu(cpu, cpus) - WRITE_ONCE(per_cpu(thermal_pressure, cpu), th_pressure); -} - /* * This function gets called by the timer code, with HZ frequency. * We call it with interrupts disabled. @@ -4029,8 +4338,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) * higher scheduling class, because otherwise those loose the * opportunity to pull in more work from other CPUs. */ - if (likely((prev->sched_class == &idle_sched_class || - prev->sched_class == &fair_sched_class) && + if (likely(prev->sched_class <= &fair_sched_class && rq->nr_running == rq->cfs.h_nr_running)) { p = pick_next_task_fair(rq, prev, rf); @@ -5519,6 +5827,11 @@ SYSCALL_DEFINE4(sched_getattr, pid_t, pid, struct sched_attr __user *, uattr, kattr.sched_nice = task_nice(p); #ifdef CONFIG_UCLAMP_TASK + /* + * This could race with another potential updater, but this is fine + * because it'll correctly read the old or the new value. We don't need + * to guarantee who wins the race as long as it doesn't return garbage. + */ kattr.sched_util_min = p->uclamp_req[UCLAMP_MIN].value; kattr.sched_util_max = p->uclamp_req[UCLAMP_MAX].value; #endif @@ -5876,7 +6189,7 @@ again: if (task_running(p_rq, p) || p->state) goto out_unlock; - yielded = curr->sched_class->yield_to_task(rq, p, preempt); + yielded = curr->sched_class->yield_to_task(rq, p); if (yielded) { schedstat_inc(rq->yld_count); /* @@ -6710,6 +7023,14 @@ void __init sched_init(void) unsigned long ptr = 0; int i; + /* Make sure the linker didn't screw up */ + BUG_ON(&idle_sched_class + 1 != &fair_sched_class || + &fair_sched_class + 1 != &rt_sched_class || + &rt_sched_class + 1 != &dl_sched_class); +#ifdef CONFIG_SMP + BUG_ON(&dl_sched_class + 1 != &stop_sched_class); +#endif + wait_bit_init(); #ifdef CONFIG_FAIR_GROUP_SCHED @@ -7431,6 +7752,8 @@ static ssize_t cpu_uclamp_write(struct kernfs_open_file *of, char *buf, if (req.ret) return req.ret; + static_branch_enable(&sched_uclamp_used); + mutex_lock(&uclamp_mutex); rcu_read_lock(); @@ -8118,4 +8441,7 @@ const u32 sched_prio_to_wmult[40] = { /* 15 */ 119304647, 148102320, 186737708, 238609294, 286331153, }; -#undef CREATE_TRACE_POINTS +void call_trace_sched_update_nr_running(struct rq *rq, int count) +{ + trace_sched_update_nr_running_tp(rq, count); +} diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c index 5cc4012572ec..8cb06c8c7eb1 100644 --- a/kernel/sched/cpudeadline.c +++ b/kernel/sched/cpudeadline.c @@ -121,6 +121,30 @@ int cpudl_find(struct cpudl *cp, struct task_struct *p, if (later_mask && cpumask_and(later_mask, cp->free_cpus, p->cpus_ptr)) { + unsigned long cap, max_cap = 0; + int cpu, max_cpu = -1; + + if (!static_branch_unlikely(&sched_asym_cpucapacity)) + return 1; + + /* Ensure the capacity of the CPUs fits the task. */ + for_each_cpu(cpu, later_mask) { + if (!dl_task_fits_capacity(p, cpu)) { + cpumask_clear_cpu(cpu, later_mask); + + cap = capacity_orig_of(cpu); + + if (cap > max_cap || + (cpu == task_cpu(p) && cap == max_cap)) { + max_cap = cap; + max_cpu = cpu; + } + } + } + + if (cpumask_empty(later_mask)) + cpumask_set_cpu(max_cpu, later_mask); + return 1; } else { int best_cpu = cpudl_maximum(cp); diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 7fbaee24c824..dc6835bc6490 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -210,7 +210,7 @@ unsigned long schedutil_cpu_util(int cpu, unsigned long util_cfs, unsigned long dl_util, util, irq; struct rq *rq = cpu_rq(cpu); - if (!IS_BUILTIN(CONFIG_UCLAMP_TASK) && + if (!uclamp_is_used() && type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) { return max; } diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index ff9435dee1df..5a55d2300452 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -520,50 +520,6 @@ void account_idle_ticks(unsigned long ticks) } /* - * Perform (stime * rtime) / total, but avoid multiplication overflow by - * losing precision when the numbers are big. - */ -static u64 scale_stime(u64 stime, u64 rtime, u64 total) -{ - u64 scaled; - - for (;;) { - /* Make sure "rtime" is the bigger of stime/rtime */ - if (stime > rtime) - swap(rtime, stime); - - /* Make sure 'total' fits in 32 bits */ - if (total >> 32) - goto drop_precision; - - /* Does rtime (and thus stime) fit in 32 bits? */ - if (!(rtime >> 32)) - break; - - /* Can we just balance rtime/stime rather than dropping bits? */ - if (stime >> 31) - goto drop_precision; - - /* We can grow stime and shrink rtime and try to make them both fit */ - stime <<= 1; - rtime >>= 1; - continue; - -drop_precision: - /* We drop from rtime, it has more bits than stime */ - rtime >>= 1; - total >>= 1; - } - - /* - * Make sure gcc understands that this is a 32x32->64 multiply, - * followed by a 64/32->64 divide. - */ - scaled = div_u64((u64) (u32) stime * (u64) (u32) rtime, (u32)total); - return scaled; -} - -/* * Adjust tick based cputime random precision against scheduler runtime * accounting. * @@ -622,7 +578,7 @@ void cputime_adjust(struct task_cputime *curr, struct prev_cputime *prev, goto update; } - stime = scale_stime(stime, rtime, stime + utime); + stime = mul_u64_u64_div_u64(stime, rtime, stime + utime); update: /* diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index f63f337c7147..3862a28cd05d 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -54,15 +54,49 @@ static inline struct dl_bw *dl_bw_of(int i) static inline int dl_bw_cpus(int i) { struct root_domain *rd = cpu_rq(i)->rd; - int cpus = 0; + int cpus; RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), "sched RCU must be held"); + + if (cpumask_subset(rd->span, cpu_active_mask)) + return cpumask_weight(rd->span); + + cpus = 0; + for_each_cpu_and(i, rd->span, cpu_active_mask) cpus++; return cpus; } + +static inline unsigned long __dl_bw_capacity(int i) +{ + struct root_domain *rd = cpu_rq(i)->rd; + unsigned long cap = 0; + + RCU_LOCKDEP_WARN(!rcu_read_lock_sched_held(), + "sched RCU must be held"); + + for_each_cpu_and(i, rd->span, cpu_active_mask) + cap += capacity_orig_of(i); + + return cap; +} + +/* + * XXX Fix: If 'rq->rd == def_root_domain' perform AC against capacity + * of the CPU the task is running on rather rd's \Sum CPU capacity. + */ +static inline unsigned long dl_bw_capacity(int i) +{ + if (!static_branch_unlikely(&sched_asym_cpucapacity) && + capacity_orig_of(i) == SCHED_CAPACITY_SCALE) { + return dl_bw_cpus(i) << SCHED_CAPACITY_SHIFT; + } else { + return __dl_bw_capacity(i); + } +} #else static inline struct dl_bw *dl_bw_of(int i) { @@ -73,6 +107,11 @@ static inline int dl_bw_cpus(int i) { return 1; } + +static inline unsigned long dl_bw_capacity(int i) +{ + return SCHED_CAPACITY_SCALE; +} #endif static inline @@ -1098,7 +1137,7 @@ void init_dl_task_timer(struct sched_dl_entity *dl_se) * cannot use the runtime, and so it replenishes the task. This rule * works fine for implicit deadline tasks (deadline == period), and the * CBS was designed for implicit deadline tasks. However, a task with - * constrained deadline (deadine < period) might be awakened after the + * constrained deadline (deadline < period) might be awakened after the * deadline, but before the next period. In this case, replenishing the * task would allow it to run for runtime / deadline. As in this case * deadline < period, CBS enables a task to run for more than the @@ -1604,6 +1643,7 @@ static int select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) { struct task_struct *curr; + bool select_rq; struct rq *rq; if (sd_flag != SD_BALANCE_WAKE) @@ -1623,10 +1663,19 @@ select_task_rq_dl(struct task_struct *p, int cpu, int sd_flag, int flags) * other hand, if it has a shorter deadline, we * try to make it stay here, it might be important. */ - if (unlikely(dl_task(curr)) && - (curr->nr_cpus_allowed < 2 || - !dl_entity_preempt(&p->dl, &curr->dl)) && - (p->nr_cpus_allowed > 1)) { + select_rq = unlikely(dl_task(curr)) && + (curr->nr_cpus_allowed < 2 || + !dl_entity_preempt(&p->dl, &curr->dl)) && + p->nr_cpus_allowed > 1; + + /* + * Take the capacity of the CPU into account to + * ensure it fits the requirement of the task. + */ + if (static_branch_unlikely(&sched_asym_cpucapacity)) + select_rq |= !dl_task_fits_capacity(p, cpu); + + if (select_rq) { int target = find_later_rq(p); if (target != -1 && @@ -2430,8 +2479,8 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p, } } -const struct sched_class dl_sched_class = { - .next = &rt_sched_class, +const struct sched_class dl_sched_class + __attribute__((section("__dl_sched_class"))) = { .enqueue_task = enqueue_task_dl, .dequeue_task = dequeue_task_dl, .yield_task = yield_task_dl, @@ -2551,11 +2600,12 @@ void sched_dl_do_global(void) int sched_dl_overflow(struct task_struct *p, int policy, const struct sched_attr *attr) { - struct dl_bw *dl_b = dl_bw_of(task_cpu(p)); u64 period = attr->sched_period ?: attr->sched_deadline; u64 runtime = attr->sched_runtime; u64 new_bw = dl_policy(policy) ? to_ratio(period, runtime) : 0; - int cpus, err = -1; + int cpus, err = -1, cpu = task_cpu(p); + struct dl_bw *dl_b = dl_bw_of(cpu); + unsigned long cap; if (attr->sched_flags & SCHED_FLAG_SUGOV) return 0; @@ -2570,15 +2620,17 @@ int sched_dl_overflow(struct task_struct *p, int policy, * allocated bandwidth of the container. */ raw_spin_lock(&dl_b->lock); - cpus = dl_bw_cpus(task_cpu(p)); + cpus = dl_bw_cpus(cpu); + cap = dl_bw_capacity(cpu); + if (dl_policy(policy) && !task_has_dl_policy(p) && - !__dl_overflow(dl_b, cpus, 0, new_bw)) { + !__dl_overflow(dl_b, cap, 0, new_bw)) { if (hrtimer_active(&p->dl.inactive_timer)) __dl_sub(dl_b, p->dl.dl_bw, cpus); __dl_add(dl_b, new_bw, cpus); err = 0; } else if (dl_policy(policy) && task_has_dl_policy(p) && - !__dl_overflow(dl_b, cpus, p->dl.dl_bw, new_bw)) { + !__dl_overflow(dl_b, cap, p->dl.dl_bw, new_bw)) { /* * XXX this is slightly incorrect: when the task * utilization decreases, we should delay the total @@ -2635,6 +2687,14 @@ void __getparam_dl(struct task_struct *p, struct sched_attr *attr) } /* + * Default limits for DL period; on the top end we guard against small util + * tasks still getting rediculous long effective runtimes, on the bottom end we + * guard against timer DoS. + */ +unsigned int sysctl_sched_dl_period_max = 1 << 22; /* ~4 seconds */ +unsigned int sysctl_sched_dl_period_min = 100; /* 100 us */ + +/* * This function validates the new parameters of a -deadline task. * We ask for the deadline not being zero, and greater or equal * than the runtime, as well as the period of being zero or @@ -2646,6 +2706,8 @@ void __getparam_dl(struct task_struct *p, struct sched_attr *attr) */ bool __checkparam_dl(const struct sched_attr *attr) { + u64 period, max, min; + /* special dl tasks don't actually use any parameter */ if (attr->sched_flags & SCHED_FLAG_SUGOV) return true; @@ -2669,12 +2731,21 @@ bool __checkparam_dl(const struct sched_attr *attr) attr->sched_period & (1ULL << 63)) return false; + period = attr->sched_period; + if (!period) + period = attr->sched_deadline; + /* runtime <= deadline <= period (if period != 0) */ - if ((attr->sched_period != 0 && - attr->sched_period < attr->sched_deadline) || + if (period < attr->sched_deadline || attr->sched_deadline < attr->sched_runtime) return false; + max = (u64)READ_ONCE(sysctl_sched_dl_period_max) * NSEC_PER_USEC; + min = (u64)READ_ONCE(sysctl_sched_dl_period_min) * NSEC_PER_USEC; + + if (period < min || period > max) + return false; + return true; } @@ -2715,19 +2786,19 @@ bool dl_param_changed(struct task_struct *p, const struct sched_attr *attr) #ifdef CONFIG_SMP int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allowed) { + unsigned long flags, cap; unsigned int dest_cpu; struct dl_bw *dl_b; bool overflow; - int cpus, ret; - unsigned long flags; + int ret; dest_cpu = cpumask_any_and(cpu_active_mask, cs_cpus_allowed); rcu_read_lock_sched(); dl_b = dl_bw_of(dest_cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); - cpus = dl_bw_cpus(dest_cpu); - overflow = __dl_overflow(dl_b, cpus, 0, p->dl.dl_bw); + cap = dl_bw_capacity(dest_cpu); + overflow = __dl_overflow(dl_b, cap, 0, p->dl.dl_bw); if (overflow) { ret = -EBUSY; } else { @@ -2737,6 +2808,8 @@ int dl_task_can_attach(struct task_struct *p, const struct cpumask *cs_cpus_allo * We will free resources in the source root_domain * later on (see set_cpus_allowed_dl()). */ + int cpus = dl_bw_cpus(dest_cpu); + __dl_add(dl_b, p->dl.dl_bw, cpus); ret = 0; } @@ -2769,16 +2842,15 @@ int dl_cpuset_cpumask_can_shrink(const struct cpumask *cur, bool dl_cpu_busy(unsigned int cpu) { - unsigned long flags; + unsigned long flags, cap; struct dl_bw *dl_b; bool overflow; - int cpus; rcu_read_lock_sched(); dl_b = dl_bw_of(cpu); raw_spin_lock_irqsave(&dl_b->lock, flags); - cpus = dl_bw_cpus(cpu); - overflow = __dl_overflow(dl_b, cpus, 0, 0); + cap = dl_bw_capacity(cpu); + overflow = __dl_overflow(dl_b, cap, 0, 0); raw_spin_unlock_irqrestore(&dl_b->lock, flags); rcu_read_unlock_sched(); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 04fa8dbcfa4d..2ba8f230feb9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -22,8 +22,6 @@ */ #include "sched.h" -#include <trace/events/sched.h> - /* * Targeted preemption latency for CPU-bound tasks: * @@ -3094,7 +3092,7 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, #ifdef CONFIG_SMP do { - u32 divider = LOAD_AVG_MAX - 1024 + se->avg.period_contrib; + u32 divider = get_pelt_divider(&se->avg); se->avg.load_avg = div_u64(se_weight(se) * se->avg.load_sum, divider); } while (0); @@ -3440,16 +3438,18 @@ static inline void update_tg_cfs_util(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq) { long delta = gcfs_rq->avg.util_avg - se->avg.util_avg; - /* - * cfs_rq->avg.period_contrib can be used for both cfs_rq and se. - * See ___update_load_avg() for details. - */ - u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib; + u32 divider; /* Nothing to update */ if (!delta) return; + /* + * cfs_rq->avg.period_contrib can be used for both cfs_rq and se. + * See ___update_load_avg() for details. + */ + divider = get_pelt_divider(&cfs_rq->avg); + /* Set new sched_entity's utilization */ se->avg.util_avg = gcfs_rq->avg.util_avg; se->avg.util_sum = se->avg.util_avg * divider; @@ -3463,16 +3463,18 @@ static inline void update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq *gcfs_rq) { long delta = gcfs_rq->avg.runnable_avg - se->avg.runnable_avg; - /* - * cfs_rq->avg.period_contrib can be used for both cfs_rq and se. - * See ___update_load_avg() for details. - */ - u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib; + u32 divider; /* Nothing to update */ if (!delta) return; + /* + * cfs_rq->avg.period_contrib can be used for both cfs_rq and se. + * See ___update_load_avg() for details. + */ + divider = get_pelt_divider(&cfs_rq->avg); + /* Set new sched_entity's runnable */ se->avg.runnable_avg = gcfs_rq->avg.runnable_avg; se->avg.runnable_sum = se->avg.runnable_avg * divider; @@ -3500,7 +3502,7 @@ update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cfs_rq * cfs_rq->avg.period_contrib can be used for both cfs_rq and se. * See ___update_load_avg() for details. */ - divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib; + divider = get_pelt_divider(&cfs_rq->avg); if (runnable_sum >= 0) { /* @@ -3646,7 +3648,7 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) if (cfs_rq->removed.nr) { unsigned long r; - u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib; + u32 divider = get_pelt_divider(&cfs_rq->avg); raw_spin_lock(&cfs_rq->removed.lock); swap(cfs_rq->removed.util_avg, removed_util); @@ -3701,7 +3703,7 @@ static void attach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *s * cfs_rq->avg.period_contrib can be used for both cfs_rq and se. * See ___update_load_avg() for details. */ - u32 divider = LOAD_AVG_MAX - 1024 + cfs_rq->avg.period_contrib; + u32 divider = get_pelt_divider(&cfs_rq->avg); /* * When we attach the @se to the @cfs_rq, we must align the decay @@ -3922,6 +3924,8 @@ static inline void util_est_enqueue(struct cfs_rq *cfs_rq, enqueued = cfs_rq->avg.util_est.enqueued; enqueued += _task_util_est(p); WRITE_ONCE(cfs_rq->avg.util_est.enqueued, enqueued); + + trace_sched_util_est_cfs_tp(cfs_rq); } /* @@ -3952,6 +3956,8 @@ util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep) ue.enqueued -= min_t(unsigned int, ue.enqueued, _task_util_est(p)); WRITE_ONCE(cfs_rq->avg.util_est.enqueued, ue.enqueued); + trace_sched_util_est_cfs_tp(cfs_rq); + /* * Skip update of task's estimated utilization when the task has not * yet completed an activation, e.g. being migrated. @@ -4017,6 +4023,8 @@ util_est_dequeue(struct cfs_rq *cfs_rq, struct task_struct *p, bool task_sleep) ue.ewma >>= UTIL_EST_WEIGHT_SHIFT; done: WRITE_ONCE(p->se.avg.util_est, ue); + + trace_sched_util_est_se_tp(&p->se); } static inline int task_fits_capacity(struct task_struct *p, long capacity) @@ -5618,14 +5626,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) } -dequeue_throttle: - if (!se) - sub_nr_running(rq, 1); + /* At this point se is NULL and we are at root level*/ + sub_nr_running(rq, 1); /* balance early to pull high priority tasks */ if (unlikely(!was_sched_idle && sched_idle_rq(rq))) rq->next_balance = jiffies; +dequeue_throttle: util_est_dequeue(&rq->cfs, p, task_sleep); hrtick_update(rq); } @@ -7161,7 +7169,7 @@ static void yield_task_fair(struct rq *rq) set_skip_buddy(se); } -static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt) +static bool yield_to_task_fair(struct rq *rq, struct task_struct *p) { struct sched_entity *se = &p->se; @@ -8049,7 +8057,7 @@ static inline void init_sd_lb_stats(struct sd_lb_stats *sds) }; } -static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu) +static unsigned long scale_rt_capacity(int cpu) { struct rq *rq = cpu_rq(cpu); unsigned long max = arch_scale_cpu_capacity(cpu); @@ -8081,7 +8089,7 @@ static unsigned long scale_rt_capacity(struct sched_domain *sd, int cpu) static void update_cpu_capacity(struct sched_domain *sd, int cpu) { - unsigned long capacity = scale_rt_capacity(sd, cpu); + unsigned long capacity = scale_rt_capacity(cpu); struct sched_group *sdg = sd->groups; cpu_rq(cpu)->cpu_capacity_orig = arch_scale_cpu_capacity(cpu); @@ -8703,8 +8711,14 @@ static bool update_pick_idlest(struct sched_group *idlest, case group_has_spare: /* Select group with most idle CPUs */ - if (idlest_sgs->idle_cpus >= sgs->idle_cpus) + if (idlest_sgs->idle_cpus > sgs->idle_cpus) + return false; + + /* Select group with lowest group_util */ + if (idlest_sgs->idle_cpus == sgs->idle_cpus && + idlest_sgs->group_util <= sgs->group_util) return false; + break; } @@ -10027,7 +10041,12 @@ static void kick_ilb(unsigned int flags) { int ilb_cpu; - nohz.next_balance++; + /* + * Increase nohz.next_balance only when if full ilb is triggered but + * not if we only update stats. + */ + if (flags & NOHZ_BALANCE_KICK) + nohz.next_balance = jiffies+1; ilb_cpu = find_new_ilb(); @@ -10348,6 +10367,14 @@ static bool _nohz_idle_balance(struct rq *this_rq, unsigned int flags, } } + /* + * next_balance will be updated only when there is a need. + * When the CPU is attached to null domain for ex, it will not be + * updated. + */ + if (likely(update_next_balance)) + nohz.next_balance = next_balance; + /* Newly idle CPU doesn't need an update */ if (idle != CPU_NEWLY_IDLE) { update_blocked_averages(this_cpu); @@ -10368,14 +10395,6 @@ abort: if (has_blocked_load) WRITE_ONCE(nohz.has_blocked, 1); - /* - * next_balance will be updated only when there is a need. - * When the CPU is attached to null domain for ex, it will not be - * updated. - */ - if (likely(update_next_balance)) - nohz.next_balance = next_balance; - return ret; } @@ -11118,8 +11137,8 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task /* * All the scheduling class methods: */ -const struct sched_class fair_sched_class = { - .next = &idle_sched_class, +const struct sched_class fair_sched_class + __attribute__((section("__fair_sched_class"))) = { .enqueue_task = enqueue_task_fair, .dequeue_task = dequeue_task_fair, .yield_task = yield_task_fair, @@ -11292,3 +11311,9 @@ const struct cpumask *sched_trace_rd_span(struct root_domain *rd) #endif } EXPORT_SYMBOL_GPL(sched_trace_rd_span); + +int sched_trace_rq_nr_running(struct rq *rq) +{ + return rq ? rq->nr_running : -1; +} +EXPORT_SYMBOL_GPL(sched_trace_rq_nr_running); diff --git a/kernel/sched/idle.c b/kernel/sched/idle.c index 1ae95b9150d3..6bf34986f45c 100644 --- a/kernel/sched/idle.c +++ b/kernel/sched/idle.c @@ -453,11 +453,6 @@ prio_changed_idle(struct rq *rq, struct task_struct *p, int oldprio) BUG(); } -static unsigned int get_rr_interval_idle(struct rq *rq, struct task_struct *task) -{ - return 0; -} - static void update_curr_idle(struct rq *rq) { } @@ -465,8 +460,8 @@ static void update_curr_idle(struct rq *rq) /* * Simple, special scheduling class for the per-CPU idle tasks: */ -const struct sched_class idle_sched_class = { - /* .next is NULL */ +const struct sched_class idle_sched_class + __attribute__((section("__idle_sched_class"))) = { /* no enqueue/yield_task for idle tasks */ /* dequeue is not valid, we print a debug message there: */ @@ -486,8 +481,6 @@ const struct sched_class idle_sched_class = { .task_tick = task_tick_idle, - .get_rr_interval = get_rr_interval_idle, - .prio_changed = prio_changed_idle, .switched_to = switched_to_idle, .update_curr = update_curr_idle, diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 808244f3ddd9..5a6ea03f9882 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -140,7 +140,8 @@ static int __init housekeeping_nohz_full_setup(char *str) { unsigned int flags; - flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC; + flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | + HK_FLAG_MISC | HK_FLAG_KTHREAD; return housekeeping_setup(str, flags); } diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c index de22da666ac7..d2a655643a02 100644 --- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -347,7 +347,7 @@ static inline void calc_global_nohz(void) { } * * Called from the global timer code. */ -void calc_global_load(unsigned long ticks) +void calc_global_load(void) { unsigned long sample_window; long active, delta; diff --git a/kernel/sched/pelt.c b/kernel/sched/pelt.c index b4b1ff96642f..2c613e1cff3a 100644 --- a/kernel/sched/pelt.c +++ b/kernel/sched/pelt.c @@ -28,8 +28,6 @@ #include "sched.h" #include "pelt.h" -#include <trace/events/sched.h> - /* * Approximate: * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) @@ -83,8 +81,6 @@ static u32 __accumulate_pelt_segments(u64 periods, u32 d1, u32 d3) return c1 + c2 + c3; } -#define cap_scale(v, s) ((v)*(s) >> SCHED_CAPACITY_SHIFT) - /* * Accumulate the three separate parts of the sum; d1 the remainder * of the last (incomplete) period, d2 the span of full periods and d3 @@ -264,7 +260,7 @@ ___update_load_sum(u64 now, struct sched_avg *sa, static __always_inline void ___update_load_avg(struct sched_avg *sa, unsigned long load) { - u32 divider = LOAD_AVG_MAX - 1024 + sa->period_contrib; + u32 divider = get_pelt_divider(sa); /* * Step 2: update *_avg. diff --git a/kernel/sched/pelt.h b/kernel/sched/pelt.h index eb034d9f024d..795e43e02afc 100644 --- a/kernel/sched/pelt.h +++ b/kernel/sched/pelt.h @@ -37,6 +37,11 @@ update_irq_load_avg(struct rq *rq, u64 running) } #endif +static inline u32 get_pelt_divider(struct sched_avg *avg) +{ + return LOAD_AVG_MAX - 1024 + avg->period_contrib; +} + /* * When a task is dequeued, its estimated utilization should not be update if * its util_avg has not been updated at least once. diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index 8f45cdb6463b..e53b711bd643 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -190,7 +190,6 @@ static void group_init(struct psi_group *group) INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work); mutex_init(&group->avgs_lock); /* Init trigger-related members */ - atomic_set(&group->poll_scheduled, 0); mutex_init(&group->trigger_lock); INIT_LIST_HEAD(&group->triggers); memset(group->nr_triggers, 0, sizeof(group->nr_triggers)); @@ -199,7 +198,7 @@ static void group_init(struct psi_group *group) memset(group->polling_total, 0, sizeof(group->polling_total)); group->polling_next_update = ULLONG_MAX; group->polling_until = 0; - rcu_assign_pointer(group->poll_kworker, NULL); + rcu_assign_pointer(group->poll_task, NULL); } void __init psi_init(void) @@ -547,47 +546,38 @@ static u64 update_triggers(struct psi_group *group, u64 now) return now + group->poll_min_period; } -/* - * Schedule polling if it's not already scheduled. It's safe to call even from - * hotpath because even though kthread_queue_delayed_work takes worker->lock - * spinlock that spinlock is never contended due to poll_scheduled atomic - * preventing such competition. - */ +/* Schedule polling if it's not already scheduled. */ static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay) { - struct kthread_worker *kworker; + struct task_struct *task; - /* Do not reschedule if already scheduled */ - if (atomic_cmpxchg(&group->poll_scheduled, 0, 1) != 0) + /* + * Do not reschedule if already scheduled. + * Possible race with a timer scheduled after this check but before + * mod_timer below can be tolerated because group->polling_next_update + * will keep updates on schedule. + */ + if (timer_pending(&group->poll_timer)) return; rcu_read_lock(); - kworker = rcu_dereference(group->poll_kworker); + task = rcu_dereference(group->poll_task); /* * kworker might be NULL in case psi_trigger_destroy races with * psi_task_change (hotpath) which can't use locks */ - if (likely(kworker)) - kthread_queue_delayed_work(kworker, &group->poll_work, delay); - else - atomic_set(&group->poll_scheduled, 0); + if (likely(task)) + mod_timer(&group->poll_timer, jiffies + delay); rcu_read_unlock(); } -static void psi_poll_work(struct kthread_work *work) +static void psi_poll_work(struct psi_group *group) { - struct kthread_delayed_work *dwork; - struct psi_group *group; u32 changed_states; u64 now; - dwork = container_of(work, struct kthread_delayed_work, work); - group = container_of(dwork, struct psi_group, poll_work); - - atomic_set(&group->poll_scheduled, 0); - mutex_lock(&group->trigger_lock); now = sched_clock(); @@ -623,6 +613,35 @@ out: mutex_unlock(&group->trigger_lock); } +static int psi_poll_worker(void *data) +{ + struct psi_group *group = (struct psi_group *)data; + struct sched_param param = { + .sched_priority = 1, + }; + + sched_setscheduler_nocheck(current, SCHED_FIFO, ¶m); + + while (true) { + wait_event_interruptible(group->poll_wait, + atomic_cmpxchg(&group->poll_wakeup, 1, 0) || + kthread_should_stop()); + if (kthread_should_stop()) + break; + + psi_poll_work(group); + } + return 0; +} + +static void poll_timer_fn(struct timer_list *t) +{ + struct psi_group *group = from_timer(group, t, poll_timer); + + atomic_set(&group->poll_wakeup, 1); + wake_up_interruptible(&group->poll_wait); +} + static void record_times(struct psi_group_cpu *groupc, int cpu, bool memstall_tick) { @@ -1099,22 +1118,20 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, mutex_lock(&group->trigger_lock); - if (!rcu_access_pointer(group->poll_kworker)) { - struct sched_param param = { - .sched_priority = 1, - }; - struct kthread_worker *kworker; + if (!rcu_access_pointer(group->poll_task)) { + struct task_struct *task; - kworker = kthread_create_worker(0, "psimon"); - if (IS_ERR(kworker)) { + task = kthread_create(psi_poll_worker, group, "psimon"); + if (IS_ERR(task)) { kfree(t); mutex_unlock(&group->trigger_lock); - return ERR_CAST(kworker); + return ERR_CAST(task); } - sched_setscheduler_nocheck(kworker->task, SCHED_FIFO, ¶m); - kthread_init_delayed_work(&group->poll_work, - psi_poll_work); - rcu_assign_pointer(group->poll_kworker, kworker); + atomic_set(&group->poll_wakeup, 0); + init_waitqueue_head(&group->poll_wait); + wake_up_process(task); + timer_setup(&group->poll_timer, poll_timer_fn, 0); + rcu_assign_pointer(group->poll_task, task); } list_add(&t->node, &group->triggers); @@ -1132,7 +1149,7 @@ static void psi_trigger_destroy(struct kref *ref) { struct psi_trigger *t = container_of(ref, struct psi_trigger, refcount); struct psi_group *group = t->group; - struct kthread_worker *kworker_to_destroy = NULL; + struct task_struct *task_to_destroy = NULL; if (static_branch_likely(&psi_disabled)) return; @@ -1158,13 +1175,13 @@ static void psi_trigger_destroy(struct kref *ref) period = min(period, div_u64(tmp->win.size, UPDATES_PER_WINDOW)); group->poll_min_period = period; - /* Destroy poll_kworker when the last trigger is destroyed */ + /* Destroy poll_task when the last trigger is destroyed */ if (group->poll_states == 0) { group->polling_until = 0; - kworker_to_destroy = rcu_dereference_protected( - group->poll_kworker, + task_to_destroy = rcu_dereference_protected( + group->poll_task, lockdep_is_held(&group->trigger_lock)); - rcu_assign_pointer(group->poll_kworker, NULL); + rcu_assign_pointer(group->poll_task, NULL); } } @@ -1172,25 +1189,23 @@ static void psi_trigger_destroy(struct kref *ref) /* * Wait for both *trigger_ptr from psi_trigger_replace and - * poll_kworker RCUs to complete their read-side critical sections - * before destroying the trigger and optionally the poll_kworker + * poll_task RCUs to complete their read-side critical sections + * before destroying the trigger and optionally the poll_task */ synchronize_rcu(); /* * Destroy the kworker after releasing trigger_lock to prevent a * deadlock while waiting for psi_poll_work to acquire trigger_lock */ - if (kworker_to_destroy) { + if (task_to_destroy) { /* * After the RCU grace period has expired, the worker - * can no longer be found through group->poll_kworker. + * can no longer be found through group->poll_task. * But it might have been already scheduled before * that - deschedule it cleanly before destroying it. */ - kthread_cancel_delayed_work_sync(&group->poll_work); - atomic_set(&group->poll_scheduled, 0); - - kthread_destroy_worker(kworker_to_destroy); + del_timer_sync(&group->poll_timer); + kthread_stop(task_to_destroy); } kfree(t); } diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index f395ddb75f38..f215eea6a966 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2429,8 +2429,8 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task) return 0; } -const struct sched_class rt_sched_class = { - .next = &fair_sched_class, +const struct sched_class rt_sched_class + __attribute__((section("__rt_sched_class"))) = { .enqueue_task = enqueue_task_rt, .dequeue_task = dequeue_task_rt, .yield_task = yield_task_rt, diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 877fb08eb1b0..3fd283892761 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -67,6 +67,7 @@ #include <linux/tsacct_kern.h> #include <asm/tlb.h> +#include <asm-generic/vmlinux.lds.h> #ifdef CONFIG_PARAVIRT # include <asm/paravirt.h> @@ -75,6 +76,8 @@ #include "cpupri.h" #include "cpudeadline.h" +#include <trace/events/sched.h> + #ifdef CONFIG_SCHED_DEBUG # define SCHED_WARN_ON(x) WARN_ONCE(x, #x) #else @@ -96,6 +99,7 @@ extern atomic_long_t calc_load_tasks; extern void calc_global_load_tick(struct rq *this_rq); extern long calc_load_fold_active(struct rq *this_rq, long adjust); +extern void call_trace_sched_update_nr_running(struct rq *rq, int count); /* * Helpers for converting nanosecond timing to jiffy resolution */ @@ -310,11 +314,26 @@ void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus) __dl_update(dl_b, -((s32)tsk_bw / cpus)); } -static inline -bool __dl_overflow(struct dl_bw *dl_b, int cpus, u64 old_bw, u64 new_bw) +static inline bool __dl_overflow(struct dl_bw *dl_b, unsigned long cap, + u64 old_bw, u64 new_bw) { return dl_b->bw != -1 && - dl_b->bw * cpus < dl_b->total_bw - old_bw + new_bw; + cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw; +} + +/* + * Verify the fitness of task @p to run on @cpu taking into account the + * CPU original capacity and the runtime/deadline ratio of the task. + * + * The function will return true if the CPU original capacity of the + * @cpu scaled by SCHED_CAPACITY_SCALE >= runtime/deadline ratio of the + * task and false otherwise. + */ +static inline bool dl_task_fits_capacity(struct task_struct *p, int cpu) +{ + unsigned long cap = arch_scale_cpu_capacity(cpu); + + return cap_scale(p->dl.dl_deadline, cap) >= p->dl.dl_runtime; } extern void init_dl_bw(struct dl_bw *dl_b); @@ -862,6 +881,8 @@ struct uclamp_rq { unsigned int value; struct uclamp_bucket bucket[UCLAMP_BUCKETS]; }; + +DECLARE_STATIC_KEY_FALSE(sched_uclamp_used); #endif /* CONFIG_UCLAMP_TASK */ /* @@ -1182,6 +1203,16 @@ struct rq_flags { #endif }; +/* + * Lockdep annotation that avoids accidental unlocks; it's like a + * sticky/continuous lockdep_assert_held(). + * + * This avoids code that has access to 'struct rq *rq' (basically everything in + * the scheduler) from accidentally unlocking the rq if they do not also have a + * copy of the (on-stack) 'struct rq_flags rf'. + * + * Also see Documentation/locking/lockdep-design.rst. + */ static inline void rq_pin_lock(struct rq *rq, struct rq_flags *rf) { rf->cookie = lockdep_pin_lock(&rq->lock); @@ -1739,7 +1770,6 @@ extern const u32 sched_prio_to_wmult[40]; #define RETRY_TASK ((void *)-1UL) struct sched_class { - const struct sched_class *next; #ifdef CONFIG_UCLAMP_TASK int uclamp_enabled; @@ -1748,7 +1778,7 @@ struct sched_class { void (*enqueue_task) (struct rq *rq, struct task_struct *p, int flags); void (*dequeue_task) (struct rq *rq, struct task_struct *p, int flags); void (*yield_task) (struct rq *rq); - bool (*yield_to_task)(struct rq *rq, struct task_struct *p, bool preempt); + bool (*yield_to_task)(struct rq *rq, struct task_struct *p); void (*check_preempt_curr)(struct rq *rq, struct task_struct *p, int flags); @@ -1796,7 +1826,7 @@ struct sched_class { #ifdef CONFIG_FAIR_GROUP_SCHED void (*task_change_group)(struct task_struct *p, int type); #endif -}; +} __aligned(STRUCT_ALIGNMENT); /* STRUCT_ALIGN(), vmlinux.lds.h */ static inline void put_prev_task(struct rq *rq, struct task_struct *prev) { @@ -1810,17 +1840,18 @@ static inline void set_next_task(struct rq *rq, struct task_struct *next) next->sched_class->set_next_task(rq, next, false); } -#ifdef CONFIG_SMP -#define sched_class_highest (&stop_sched_class) -#else -#define sched_class_highest (&dl_sched_class) -#endif +/* Defined in include/asm-generic/vmlinux.lds.h */ +extern struct sched_class __begin_sched_classes[]; +extern struct sched_class __end_sched_classes[]; + +#define sched_class_highest (__end_sched_classes - 1) +#define sched_class_lowest (__begin_sched_classes - 1) #define for_class_range(class, _from, _to) \ - for (class = (_from); class != (_to); class = class->next) + for (class = (_from); class != (_to); class--) #define for_each_class(class) \ - for_class_range(class, sched_class_highest, NULL) + for_class_range(class, sched_class_highest, sched_class_lowest) extern const struct sched_class stop_sched_class; extern const struct sched_class dl_sched_class; @@ -1930,12 +1961,7 @@ extern int __init sched_tick_offload_init(void); */ static inline void sched_update_tick_dependency(struct rq *rq) { - int cpu; - - if (!tick_nohz_full_enabled()) - return; - - cpu = cpu_of(rq); + int cpu = cpu_of(rq); if (!tick_nohz_full_cpu(cpu)) return; @@ -1955,6 +1981,9 @@ static inline void add_nr_running(struct rq *rq, unsigned count) unsigned prev_nr = rq->nr_running; rq->nr_running = prev_nr + count; + if (trace_sched_update_nr_running_tp_enabled()) { + call_trace_sched_update_nr_running(rq, count); + } #ifdef CONFIG_SMP if (prev_nr < 2 && rq->nr_running >= 2) { @@ -1969,6 +1998,10 @@ static inline void add_nr_running(struct rq *rq, unsigned count) static inline void sub_nr_running(struct rq *rq, unsigned count) { rq->nr_running -= count; + if (trace_sched_update_nr_running_tp_enabled()) { + call_trace_sched_update_nr_running(rq, count); + } + /* Check if we still need preemption */ sched_update_tick_dependency(rq); } @@ -2016,6 +2049,16 @@ void arch_scale_freq_tick(void) #endif #ifndef arch_scale_freq_capacity +/** + * arch_scale_freq_capacity - get the frequency scale factor of a given CPU. + * @cpu: the CPU in question. + * + * Return: the frequency scale factor normalized against SCHED_CAPACITY_SCALE, i.e. + * + * f_curr + * ------ * SCHED_CAPACITY_SCALE + * f_max + */ static __always_inline unsigned long arch_scale_freq_capacity(int cpu) { @@ -2349,12 +2392,35 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {} #ifdef CONFIG_UCLAMP_TASK unsigned long uclamp_eff_value(struct task_struct *p, enum uclamp_id clamp_id); +/** + * uclamp_rq_util_with - clamp @util with @rq and @p effective uclamp values. + * @rq: The rq to clamp against. Must not be NULL. + * @util: The util value to clamp. + * @p: The task to clamp against. Can be NULL if you want to clamp + * against @rq only. + * + * Clamps the passed @util to the max(@rq, @p) effective uclamp values. + * + * If sched_uclamp_used static key is disabled, then just return the util + * without any clamping since uclamp aggregation at the rq level in the fast + * path is disabled, rendering this operation a NOP. + * + * Use uclamp_eff_value() if you don't care about uclamp values at rq level. It + * will return the correct effective uclamp value of the task even if the + * static key is disabled. + */ static __always_inline unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, struct task_struct *p) { - unsigned long min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); - unsigned long max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); + unsigned long min_util; + unsigned long max_util; + + if (!static_branch_likely(&sched_uclamp_used)) + return util; + + min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value); + max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value); if (p) { min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN)); @@ -2371,6 +2437,19 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, return clamp(util, min_util, max_util); } + +/* + * When uclamp is compiled in, the aggregation at rq level is 'turned off' + * by default in the fast path and only gets turned on once userspace performs + * an operation that requires it. + * + * Returns true if userspace opted-in to use uclamp and aggregation at rq level + * hence is active. + */ +static inline bool uclamp_is_used(void) +{ + return static_branch_likely(&sched_uclamp_used); +} #else /* CONFIG_UCLAMP_TASK */ static inline unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, @@ -2378,6 +2457,11 @@ unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util, { return util; } + +static inline bool uclamp_is_used(void) +{ + return false; +} #endif /* CONFIG_UCLAMP_TASK */ #ifdef arch_scale_freq_capacity diff --git a/kernel/sched/stop_task.c b/kernel/sched/stop_task.c index 4c9e9975684f..394bc8126a1e 100644 --- a/kernel/sched/stop_task.c +++ b/kernel/sched/stop_task.c @@ -102,12 +102,6 @@ prio_changed_stop(struct rq *rq, struct task_struct *p, int oldprio) BUG(); /* how!?, what priority? */ } -static unsigned int -get_rr_interval_stop(struct rq *rq, struct task_struct *task) -{ - return 0; -} - static void update_curr_stop(struct rq *rq) { } @@ -115,8 +109,8 @@ static void update_curr_stop(struct rq *rq) /* * Simple, special scheduling class for the per-CPU stop tasks: */ -const struct sched_class stop_sched_class = { - .next = &dl_sched_class, +const struct sched_class stop_sched_class + __attribute__((section("__stop_sched_class"))) = { .enqueue_task = enqueue_task_stop, .dequeue_task = dequeue_task_stop, @@ -136,8 +130,6 @@ const struct sched_class stop_sched_class = { .task_tick = task_tick_stop, - .get_rr_interval = get_rr_interval_stop, - .prio_changed = prio_changed_stop, .switched_to = switched_to_stop, .update_curr = update_curr_stop, diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index ba81187bb7af..9079d865a935 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1328,7 +1328,7 @@ sd_init(struct sched_domain_topology_level *tl, sd_flags = (*tl->sd_flags)(); if (WARN_ONCE(sd_flags & ~TOPOLOGY_SD_FLAGS, "wrong sd_flags in topology description\n")) - sd_flags &= ~TOPOLOGY_SD_FLAGS; + sd_flags &= TOPOLOGY_SD_FLAGS; /* Apply detected topology flags */ sd_flags |= dflags; diff --git a/kernel/smp.c b/kernel/smp.c index aa17eedff5be..d0ae8eb6bf8b 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -634,8 +634,7 @@ static int __init nrcpus(char *str) { int nr_cpus; - get_option(&str, &nr_cpus); - if (nr_cpus > 0 && nr_cpus < nr_cpu_ids) + if (get_option(&str, &nr_cpus) && nr_cpus > 0 && nr_cpus < nr_cpu_ids) nr_cpu_ids = nr_cpus; return 0; diff --git a/kernel/sysctl.c b/kernel/sysctl.c index db1ce7af2563..1b4d2dc270a5 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1780,6 +1780,20 @@ static struct ctl_table kern_table[] = { .proc_handler = sched_rt_handler, }, { + .procname = "sched_deadline_period_max_us", + .data = &sysctl_sched_dl_period_max, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + { + .procname = "sched_deadline_period_min_us", + .data = &sysctl_sched_dl_period_min, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + { .procname = "sched_rr_timeslice_ms", .data = &sysctl_sched_rr_timeslice, .maxlen = sizeof(int), @@ -1801,6 +1815,13 @@ static struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = sysctl_sched_uclamp_handler, }, + { + .procname = "sched_util_clamp_min_rt_default", + .data = &sysctl_sched_uclamp_util_min_rt_default, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = sysctl_sched_uclamp_handler, + }, #endif #ifdef CONFIG_SCHED_AUTOGROUP { diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index d20d489841c8..63a632f9896c 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -2193,7 +2193,7 @@ EXPORT_SYMBOL(ktime_get_coarse_ts64); void do_timer(unsigned long ticks) { jiffies_64 += ticks; - calc_global_load(ticks); + calc_global_load(); } /** diff --git a/lib/cpumask.c b/lib/cpumask.c index fb22fb266f93..85da6ab4fbb5 100644 --- a/lib/cpumask.c +++ b/lib/cpumask.c @@ -6,6 +6,7 @@ #include <linux/export.h> #include <linux/memblock.h> #include <linux/numa.h> +#include <linux/sched/isolation.h> /** * cpumask_next - get the next cpu in a cpumask @@ -205,22 +206,27 @@ void __init free_bootmem_cpumask_var(cpumask_var_t mask) */ unsigned int cpumask_local_spread(unsigned int i, int node) { - int cpu; + int cpu, hk_flags; + const struct cpumask *mask; + hk_flags = HK_FLAG_DOMAIN | HK_FLAG_MANAGED_IRQ; + mask = housekeeping_cpumask(hk_flags); /* Wrap: we always want a cpu. */ - i %= num_online_cpus(); + i %= cpumask_weight(mask); if (node == NUMA_NO_NODE) { - for_each_cpu(cpu, cpu_online_mask) + for_each_cpu(cpu, mask) { if (i-- == 0) return cpu; + } } else { /* NUMA first. */ - for_each_cpu_and(cpu, cpumask_of_node(node), cpu_online_mask) + for_each_cpu_and(cpu, cpumask_of_node(node), mask) { if (i-- == 0) return cpu; + } - for_each_cpu(cpu, cpu_online_mask) { + for_each_cpu(cpu, mask) { /* Skip NUMA nodes, done above. */ if (cpumask_test_cpu(cpu, cpumask_of_node(node))) continue; diff --git a/lib/math/div64.c b/lib/math/div64.c index 368ca7fd0d82..3952a07130d8 100644 --- a/lib/math/div64.c +++ b/lib/math/div64.c @@ -190,3 +190,44 @@ u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) return __iter_div_u64_rem(dividend, divisor, remainder); } EXPORT_SYMBOL(iter_div_u64_rem); + +#ifndef mul_u64_u64_div_u64 +u64 mul_u64_u64_div_u64(u64 a, u64 b, u64 c) +{ + u64 res = 0, div, rem; + int shift; + + /* can a * b overflow ? */ + if (ilog2(a) + ilog2(b) > 62) { + /* + * (b * a) / c is equal to + * + * (b / c) * a + + * (b % c) * a / c + * + * if nothing overflows. Can the 1st multiplication + * overflow? Yes, but we do not care: this can only + * happen if the end result can't fit in u64 anyway. + * + * So the code below does + * + * res = (b / c) * a; + * b = b % c; + */ + div = div64_u64_rem(b, c, &rem); + res = div * a; + b = rem; + + shift = ilog2(a) + ilog2(b) - 62; + if (shift > 0) { + /* drop precision */ + b >>= shift; + c >>= shift; + if (!c) + return res; + } + } + + return res + div64_u64(a * b, c); +} +#endif diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c index 7bd6440c63bf..9de33b594ff2 100644 --- a/net/core/net-sysfs.c +++ b/net/core/net-sysfs.c @@ -11,6 +11,7 @@ #include <linux/if_arp.h> #include <linux/slab.h> #include <linux/sched/signal.h> +#include <linux/sched/isolation.h> #include <linux/nsproxy.h> #include <net/sock.h> #include <net/net_namespace.h> @@ -741,7 +742,7 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue, { struct rps_map *old_map, *map; cpumask_var_t mask; - int err, cpu, i; + int err, cpu, i, hk_flags; static DEFINE_MUTEX(rps_map_mutex); if (!capable(CAP_NET_ADMIN)) @@ -756,6 +757,13 @@ static ssize_t store_rps_map(struct netdev_rx_queue *queue, return err; } + hk_flags = HK_FLAG_DOMAIN | HK_FLAG_WQ; + cpumask_and(mask, mask, housekeeping_cpumask(hk_flags)); + if (cpumask_empty(mask)) { + free_cpumask_var(mask); + return -EINVAL; + } + map = kzalloc(max_t(unsigned int, RPS_MAP_SIZE(cpumask_weight(mask)), L1_CACHE_BYTES), GFP_KERNEL); |