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With the new mechanism which kicks tasks off the outgoing CPU at the end of
schedule() the situation on an outgoing CPU right before the stopper thread
brings it down completely is:
- All user tasks and all unbound kernel threads have either been migrated
away or are not running and the next wakeup will move them to a online CPU.
- All per CPU kernel threads, except cpu hotplug thread and the stopper
thread have either been unbound or parked by the responsible CPU hotplug
callback.
That means that at the last step before the stopper thread is invoked the
cpu hotplug thread is the last legitimate running task on the outgoing
CPU.
Add a final wait step right before the stopper thread is kicked which
ensures that any still running tasks on the way to park or on the way to
kick themself of the CPU are either sleeping or gone.
This allows to remove the migrate_tasks() crutch in sched_cpu_dying(). If
sched_cpu_dying() detects that there is still another running task aside of
the stopper thread then it will explode with the appropriate fireworks.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lkml.kernel.org/r/20201023102346.547163969@infradead.org
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RT kernels need to ensure that all tasks which are not per CPU kthreads
have left the outgoing CPU to guarantee that no tasks are force migrated
within a migrate disabled section.
There is also some desire to (ab)use fine grained CPU hotplug control to
clear a CPU from active state to force migrate tasks which are not per CPU
kthreads away for power control purposes.
Add a mechanism which waits until all tasks which should leave the CPU
after the CPU active flag is cleared have moved to a different online CPU.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lkml.kernel.org/r/20201023102346.377836842@infradead.org
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In preparation for migrate_disable(), make sure only per-cpu kthreads
are allowed to run on !active CPUs.
This is ran (as one of the very first steps) from the cpu-hotplug
task which is a per-cpu kthread and completion of the hotplug
operation only requires such tasks.
This constraint enables the migrate_disable() implementation to wait
for completion of all migrate_disable regions on this CPU at hotplug
time without fear of any new ones starting.
This replaces the unlikely(rq->balance_callbacks) test at the tail of
context_switch with an unlikely(rq->balance_work), the fast path is
not affected.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lkml.kernel.org/r/20201023102346.292709163@infradead.org
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The intent of balance_callback() has always been to delay executing
balancing operations until the end of the current rq->lock section.
This is because balance operations must often drop rq->lock, and that
isn't safe in general.
However, as noted by Scott, there were a few holes in that scheme;
balance_callback() was called after rq->lock was dropped, which means
another CPU can interleave and touch the callback list.
Rework code to call the balance callbacks before dropping rq->lock
where possible, and otherwise splice the balance list onto a local
stack.
This guarantees that the balance list must be empty when we take
rq->lock. IOW, we'll only ever run our own balance callbacks.
Reported-by: Scott Wood <swood@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lkml.kernel.org/r/20201023102346.203901269@infradead.org
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Crashes in stop-machine are hard to connect to the calling code, add a
little something to help with that.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lkml.kernel.org/r/20201023102346.116513635@infradead.org
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As commit:
39f23ce07b93 ("sched/fair: Fix unthrottle_cfs_rq() for leaf_cfs_rq list")
does in unthrottle_cfs_rq(), throttle_cfs_rq() can also use the same
pattern as dequeue_task_fair().
No functional changes.
Signed-off-by: Peng Wang <rocking@linux.alibaba.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Phil Auld <pauld@redhat.com>
Cc: Ben Segall <bsegall@google.com>
Link: https://lore.kernel.org/r/f11dd2e3ab35cc538e2eb57bf0c99b6eaffce127.1604973978.git.rocking@linux.alibaba.com
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In the case of a thread wakeup, wake_affine determines whether a core
will be chosen for the thread on the socket where the thread ran
previously or on the socket of the waker. This is done primarily by
comparing the load of the core where th thread ran previously (prev)
and the load of the waker (this).
commit 11f10e5420f6 ("sched/fair: Use load instead of runnable load
in wakeup path") changed the load computation from the runnable load
to the load average, where the latter includes the load of threads
that have already blocked on the core.
When a short-running daemon processes happens to run on prev, this
change raised the situation that prev could appear to have a greater
load than this, even when prev is actually idle. When prev and this
are on the same socket, the idle prev is detected later, in
select_idle_sibling. But if that does not hold, prev is completely
ignored, causing the waking thread to move to the socket of the waker.
In the case of N mostly active threads on N cores, this triggers other
migrations and hurts performance.
In contrast, before commit 11f10e5420f6, the load on an idle core
was 0, and in the case of a non-idle waker core, the effect of
wake_affine was to select prev as the target for searching for a core
for the waking thread.
To avoid unnecessary migrations, extend wake_affine_idle to check
whether the core where the thread previously ran is currently idle,
and if so simply return that core as the target.
[1] commit 11f10e5420f6ce ("sched/fair: Use load instead of runnable
load in wakeup path")
This particularly has an impact when using the ondemand power manager,
where kworkers run every 0.004 seconds on all cores, increasing the
likelihood that an idle core will be considered to have a load.
The following numbers were obtained with the benchmarking tool
hyperfine (https://github.com/sharkdp/hyperfine) on the NAS parallel
benchmarks (https://www.nas.nasa.gov/publications/npb.html). The
tests were run on an 80-core Intel(R) Xeon(R) CPU E7-8870 v4 @
2.10GHz. Active (intel_pstate) and passive (intel_cpufreq) power
management were used. Times are in seconds. All experiments use all
160 hardware threads.
v5.9/intel-pstate v5.9+patch/intel-pstate
bt.C.c 24.725724+-0.962340 23.349608+-1.607214
lu.C.x 29.105952+-4.804203 25.249052+-5.561617
sp.C.x 31.220696+-1.831335 30.227760+-2.429792
ua.C.x 26.606118+-1.767384 25.778367+-1.263850
v5.9/ondemand v5.9+patch/ondemand
bt.C.c 25.330360+-1.028316 23.544036+-1.020189
lu.C.x 35.872659+-4.872090 23.719295+-3.883848
sp.C.x 32.141310+-2.289541 29.125363+-0.872300
ua.C.x 29.024597+-1.667049 25.728888+-1.539772
On the smaller data sets (A and B) and on the other NAS benchmarks
there is no impact on performance.
This also has a major impact on the splash2x.volrend benchmark of the
parsec benchmark suite that goes from 1m25 without this patch to 0m45,
in active (intel_pstate) mode.
Fixes: 11f10e5420f6 ("sched/fair: Use load instead of runnable load in wakeup path")
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lkml.kernel.org/r/1603372550-14680-1-git-send-email-Julia.Lawall@inria.fr
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Florian reported that all of kernel/sched/ is rebuild when
CONFIG_BLK_DEV_INITRD is changed, which, while not a bug is
unexpected. This is due to us including vmlinux.lds.h.
Jakub explained that the problem is that we put the alignment
requirement on the type instead of on a variable. Type alignment is a
minimum, the compiler is free to pick any larger alignment for a
specific instance of the type (eg. the variable).
So force the type alignment on all individual variable definitions and
remove the undesired dependency on vmlinux.lds.h.
Fixes: 85c2ce9104eb ("sched, vmlinux.lds: Increase STRUCT_ALIGNMENT to 64 bytes for GCC-4.9")
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Suggested-by: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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do_sched_yield() invokes schedule() with interrupts disabled which is
not allowed. This goes back to the pre git era to commit a6efb709806c
("[PATCH] irqlock patch 2.5.27-H6") in the history tree.
Reenable interrupts and remove the misleading comment which "explains" it.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/87r1pt7y5c.fsf@nanos.tec.linutronix.de
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Document membarrier ordering scenarios in membarrier.c. Thanks to Alan
Stern for refreshing my memory. Now that I have those in mind, it seems
appropriate to serialize them to comments for posterity.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201020134715.13909-4-mathieu.desnoyers@efficios.com
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Add comments and memory barrier to kthread_use_mm and kthread_unuse_mm
to allow the effect of membarrier(2) to apply to kthreads accessing
user-space memory as well.
Given that no prior kthread use this guarantee and that it only affects
kthreads, adding this guarantee does not affect user-space ABI.
Refine the check in membarrier_global_expedited to exclude runqueues
running the idle thread rather than all kthreads from the IPI cpumask.
Now that membarrier_global_expedited can IPI kthreads, the scheduler
also needs to update the runqueue's membarrier_state when entering lazy
TLB state.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201020134715.13909-3-mathieu.desnoyers@efficios.com
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exit_mm should issue memory barriers after user-space memory accesses,
before clearing current->mm, to order user-space memory accesses
performed prior to exit_mm before clearing tsk->mm, which has the
effect of skipping the membarrier private expedited IPIs.
exit_mm should also update the runqueue's membarrier_state so
membarrier global expedited IPIs are not sent when they are not
needed.
The membarrier system call can be issued concurrently with do_exit
if we have thread groups created with CLONE_VM but not CLONE_THREAD.
Here is the scenario I have in mind:
Two thread groups are created, A and B. Thread group B is created by
issuing clone from group A with flag CLONE_VM set, but not CLONE_THREAD.
Let's assume we have a single thread within each thread group (Thread A
and Thread B).
The AFAIU we can have:
Userspace variables:
int x = 0, y = 0;
CPU 0 CPU 1
Thread A Thread B
(in thread group A) (in thread group B)
x = 1
barrier()
y = 1
exit()
exit_mm()
current->mm = NULL;
r1 = load y
membarrier()
skips CPU 0 (no IPI) because its current mm is NULL
r2 = load x
BUG_ON(r1 == 1 && r2 == 0)
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201020134715.13909-2-mathieu.desnoyers@efficios.com
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It is possible for find_new_ilb() to select the current CPU, however,
this only happens from newidle balancing, in which case need_resched()
will be true, and consequently nohz_csd_func() will not trigger the
softirq.
Exclude the current CPU from becoming an ILB target.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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Add CPUPRI_HIGHER above the RT99 priority to denote the CPU is in use
by higher priority tasks (specifically deadline).
XXX: we should probably drive PUSH-PULL from cpupri, that would
automagically result in an RT-PUSH when DL sets cpupri to CPUPRI_HIGHER.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
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This makes the mapping continuous and frees up 100 for other usage.
Prev mapping:
p->rt_priority p->prio newpri cpupri
-1 -1 (CPUPRI_INVALID)
100 0 (CPUPRI_NORMAL)
1 98 98 1
...
49 50 50 49
50 49 49 50
...
99 0 0 99
New mapping:
p->rt_priority p->prio newpri cpupri
-1 -1 (CPUPRI_INVALID)
99 0 (CPUPRI_NORMAL)
1 98 98 1
...
49 50 50 49
50 49 49 50
...
99 0 0 99
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
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pri_to_cpu[1] isn't used since cpupri_set(..., newpri) is
never called with newpri = 99.
The valid RT priorities RT1..RT99 (p->rt_priority = [1..99]) map into
cpupri (idx of pri_to_cpu[]) = [2..100]
Current mapping:
p->rt_priority p->prio newpri cpupri
-1 -1 (CPUPRI_INVALID)
100 0 (CPUPRI_NORMAL)
1 98 98 2
...
49 50 50 50
50 49 49 51
...
99 0 0 100
So cpupri = 1 isn't used.
Reduce the size of pri_to_cpu[] by 1 and adapt the cpupri
implementation accordingly. This will save a useless for loop with an
atomic_read in cpupri_find_fitness() calling __cpupri_find().
New mapping:
p->rt_priority p->prio newpri cpupri
-1 -1 (CPUPRI_INVALID)
100 0 (CPUPRI_NORMAL)
1 98 98 1
...
49 50 50 49
50 49 49 50
...
99 0 0 99
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200922083934.19275-3-dietmar.eggemann@arm.com
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pri_to_cpu[CPUPRI_IDLE=0] isn't used since cpupri_set(..., newpri) is
never called with newpri = MAX_PRIO (140).
Current mapping:
p->rt_priority p->prio newpri cpupri
-1 -1 (CPUPRI_INVALID)
140 0 (CPUPRI_IDLE)
100 1 (CPUPRI_NORMAL)
1 98 98 3
...
49 50 50 51
50 49 49 52
...
99 0 0 101
Even when cpupri was introduced with commit 6e0534f27819 ("sched: use a
2-d bitmap for searching lowest-pri CPU") in v2.6.27, only
(1) CPUPRI_INVALID (-1),
(2) MAX_RT_PRIO (100),
(3) an RT prio (RT1..RT99)
were used as newprio in cpupri_set(..., newpri) -> convert_prio(newpri).
MAX_RT_PRIO is used only in dec_rt_tasks() -> dec_rt_prio() ->
dec_rt_prio_smp() -> cpupri_set() in case of !rt_rq->rt_nr_running.
I.e. it stands for a non-rt task, including the IDLE task.
Commit 57785df5ac53 ("sched: Fix task priority bug") removed code in
v2.6.33 which did set the priority of the IDLE task to MAX_PRIO.
Although this happened after the introduction of cpupri, it didn't have
an effect on the values used for cpupri_set(..., newpri).
Remove CPUPRI_IDLE and adapt the cpupri implementation accordingly.
This will save a useless for loop with an atomic_read in
cpupri_find_fitness() calling __cpupri_find().
New mapping:
p->rt_priority p->prio newpri cpupri
-1 -1 (CPUPRI_INVALID)
100 0 (CPUPRI_NORMAL)
1 98 98 2
...
49 50 50 50
50 49 49 51
...
99 0 0 100
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200922083934.19275-2-dietmar.eggemann@arm.com
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When change sched_rt_{runtime, period}_us, we validate that the new
settings should at least accommodate the currently allocated -dl
bandwidth:
sched_rt_handler()
--> sched_dl_bandwidth_validate()
{
new_bw = global_rt_runtime()/global_rt_period();
for_each_possible_cpu(cpu) {
dl_b = dl_bw_of(cpu);
if (new_bw < dl_b->total_bw) <-------
ret = -EBUSY;
}
}
But under CONFIG_SMP, dl_bw is per root domain , but not per CPU,
dl_b->total_bw is the allocated bandwidth of the whole root domain.
Instead, we should compare dl_b->total_bw against "cpus*new_bw",
where 'cpus' is the number of CPUs of the root domain.
Also, below annotation(in kernel/sched/sched.h) implied implementation
only appeared in SCHED_DEADLINE v2[1], then deadline scheduler kept
evolving till got merged(v9), but the annotation remains unchanged,
meaningless and misleading, update it.
* With respect to SMP, the bandwidth is given on a per-CPU basis,
* meaning that:
* - dl_bw (< 100%) is the bandwidth of the system (group) on each CPU;
* - dl_total_bw array contains, in the i-eth element, the currently
* allocated bandwidth on the i-eth CPU.
[1]: https://lore.kernel.org/lkml/1267385230.13676.101.camel@Palantir/
Fixes: 332ac17ef5bf ("sched/deadline: Add bandwidth management for SCHED_DEADLINE tasks")
Signed-off-by: Peng Liu <iwtbavbm@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/db6bbda316048cda7a1bbc9571defde193a8d67e.1602171061.git.iwtbavbm@gmail.com
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Under CONFIG_SMP, dl_bw is per root domain, but not per CPU.
When checking or updating dl_bw, currently iterating every CPU is
overdoing, just need iterate each root domain once.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Peng Liu <iwtbavbm@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/78d21ee792cc48ff79e8cd62a5f26208463684d6.1602171061.git.iwtbavbm@gmail.com
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When the sched_schedstat changes from 0 to 1, some sched se maybe
already in the runqueue, the se->statistics.wait_start will be 0.
So it will let the (rq_of(cfs_rq)) - se->statistics.wait_start)
wrong. We need to avoid this scenario.
Signed-off-by: jun qian <qianjun.kernel@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lkml.kernel.org/r/20201015064846.19809-1-qianjun.kernel@gmail.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull core entry/exit updates from Thomas Gleixner:
"A set of updates for entry/exit handling:
- More generalization of entry/exit functionality
- The consolidation work to reclaim TIF flags on x86 and also for
non-x86 specific TIF flags which are solely relevant for syscall
related work and have been moved into their own storage space. The
x86 specific part had to be merged in to avoid a major conflict.
- The TIF_NOTIFY_SIGNAL work which replaces the inefficient signal
delivery mode of task work and results in an impressive performance
improvement for io_uring. The non-x86 consolidation of this is
going to come seperate via Jens.
- The selective syscall redirection facility which provides a clean
and efficient way to support the non-Linux syscalls of WINE by
catching them at syscall entry and redirecting them to the user
space emulation. This can be utilized for other purposes as well
and has been designed carefully to avoid overhead for the regular
fastpath. This includes the core changes and the x86 support code.
- Simplification of the context tracking entry/exit handling for the
users of the generic entry code which guarantee the proper ordering
and protection.
- Preparatory changes to make the generic entry code accomodate S390
specific requirements which are mostly related to their syscall
restart mechanism"
* tag 'core-entry-2020-12-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
entry: Add syscall_exit_to_user_mode_work()
entry: Add exit_to_user_mode() wrapper
entry_Add_enter_from_user_mode_wrapper
entry: Rename exit_to_user_mode()
entry: Rename enter_from_user_mode()
docs: Document Syscall User Dispatch
selftests: Add benchmark for syscall user dispatch
selftests: Add kselftest for syscall user dispatch
entry: Support Syscall User Dispatch on common syscall entry
kernel: Implement selective syscall userspace redirection
signal: Expose SYS_USER_DISPATCH si_code type
x86: vdso: Expose sigreturn address on vdso to the kernel
MAINTAINERS: Add entry for common entry code
entry: Fix boot for !CONFIG_GENERIC_ENTRY
x86: Support HAVE_CONTEXT_TRACKING_OFFSTACK
context_tracking: Only define schedule_user() on !HAVE_CONTEXT_TRACKING_OFFSTACK archs
sched: Detect call to schedule from critical entry code
context_tracking: Don't implement exception_enter/exit() on CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK
context_tracking: Introduce HAVE_CONTEXT_TRACKING_OFFSTACK
x86: Reclaim unused x86 TI flags
...
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!HAVE_CONTEXT_TRACKING_OFFSTACK archs
schedule_user() was traditionally used by the entry code's tail to
preempt userspace after the call to user_enter(). Indeed the call to
user_enter() used to be performed upon syscall exit slow path which was
right before the last opportunity to schedule() while resuming to
userspace. The context tracking state had to be saved on the task stack
and set back to CONTEXT_KERNEL temporarily in order to safely switch to
another task.
Only a few archs use it now (namely sparc64 and powerpc64) and those
implementing HAVE_CONTEXT_TRACKING_OFFSTACK definetly can't rely on it.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201117151637.259084-5-frederic@kernel.org
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Detect calls to schedule() between user_enter() and user_exit(). Those
are symptoms of early entry code that either forgot to protect a call
to schedule() inside exception_enter()/exception_exit() or, in the case
of HAVE_CONTEXT_TRACKING_OFFSTACK, enabled interrupts or preemption in
a wrong spot.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201117151637.259084-4-frederic@kernel.org
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membarrier()'s MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE is documented as
syncing the core on all sibling threads but not necessarily the calling
thread. This behavior is fundamentally buggy and cannot be used safely.
Suppose a user program has two threads. Thread A is on CPU 0 and thread B
is on CPU 1. Thread A modifies some text and calls
membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE).
Then thread B executes the modified code. If, at any point after
membarrier() decides which CPUs to target, thread A could be preempted and
replaced by thread B on CPU 0. This could even happen on exit from the
membarrier() syscall. If this happens, thread B will end up running on CPU
0 without having synced.
In principle, this could be fixed by arranging for the scheduler to issue
sync_core_before_usermode() whenever switching between two threads in the
same mm if there is any possibility of a concurrent membarrier() call, but
this would have considerable overhead. Instead, make membarrier() sync the
calling CPU as well.
As an optimization, this avoids an extra smp_mb() in the default
barrier-only mode and an extra rseq preempt on the caller.
Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/r/250ded637696d490c69bef1877148db86066881c.1607058304.git.luto@kernel.org
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membarrier() does not explicitly sync_core() remote CPUs; instead, it
relies on the assumption that an IPI will result in a core sync. On x86,
this may be true in practice, but it's not architecturally reliable. In
particular, the SDM and APM do not appear to guarantee that interrupt
delivery is serializing. While IRET does serialize, IPI return can
schedule, thereby switching to another task in the same mm that was
sleeping in a syscall. The new task could then SYSRET back to usermode
without ever executing IRET.
Make this more robust by explicitly calling sync_core_before_usermode()
on remote cores. (This also helps people who search the kernel tree for
instances of sync_core() and sync_core_before_usermode() -- one might be
surprised that the core membarrier code doesn't currently show up in a
such a search.)
Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/776b448d5f7bd6b12690707f5ed67bcda7f1d427.1607058304.git.luto@kernel.org
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It seems that most RSEQ membarrier users will expect any stores done before
the membarrier() syscall to be visible to the target task(s). While this
is extremely likely to be true in practice, nothing actually guarantees it
by a strict reading of the x86 manuals. Rather than providing this
guarantee by accident and potentially causing a problem down the road, just
add an explicit barrier.
Fixes: 70216e18e519 ("membarrier: Provide core serializing command, *_SYNC_CORE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/d3e7197e034fa4852afcf370ca49c30496e58e40.1607058304.git.luto@kernel.org
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking fixes from Thomas Gleixner:
"Two more places which invoke tracing from RCU disabled regions in the
idle path.
Similar to the entry path the low level idle functions have to be
non-instrumentable"
* tag 'locking-urgent-2020-11-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
intel_idle: Fix intel_idle() vs tracing
sched/idle: Fix arch_cpu_idle() vs tracing
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We call arch_cpu_idle() with RCU disabled, but then use
local_irq_{en,dis}able(), which invokes tracing, which relies on RCU.
Switch all arch_cpu_idle() implementations to use
raw_local_irq_{en,dis}able() and carefully manage the
lockdep,rcu,tracing state like we do in entry.
(XXX: we really should change arch_cpu_idle() to not return with
interrupts enabled)
Reported-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lkml.kernel.org/r/20201120114925.594122626@infradead.org
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
"A couple of scheduler fixes:
- Make the conditional update of the overutilized state work
correctly by caching the relevant flags state before overwriting
them and checking them afterwards.
- Fix a data race in the wakeup path which caused loadavg on ARM64
platforms to become a random number generator.
- Fix the ordering of the iowaiter accounting operations so it can't
be decremented before it is incremented.
- Fix a bug in the deadline scheduler vs. priority inheritance when a
non-deadline task A has inherited the parameters of a deadline task
B and then blocks on a non-deadline task C.
The second inheritance step used the static deadline parameters of
task A, which are usually 0, instead of further propagating task
B's parameters. The zero initialized parameters trigger a bug in
the deadline scheduler"
* tag 'sched-urgent-2020-11-22' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/deadline: Fix priority inheritance with multiple scheduling classes
sched: Fix rq->nr_iowait ordering
sched: Fix data-race in wakeup
sched/fair: Fix overutilized update in enqueue_task_fair()
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Glenn reported that "an application [he developed produces] a BUG in
deadline.c when a SCHED_DEADLINE task contends with CFS tasks on nested
PTHREAD_PRIO_INHERIT mutexes. I believe the bug is triggered when a CFS
task that was boosted by a SCHED_DEADLINE task boosts another CFS task
(nested priority inheritance).
------------[ cut here ]------------
kernel BUG at kernel/sched/deadline.c:1462!
invalid opcode: 0000 [#1] PREEMPT SMP
CPU: 12 PID: 19171 Comm: dl_boost_bug Tainted: ...
Hardware name: ...
RIP: 0010:enqueue_task_dl+0x335/0x910
Code: ...
RSP: 0018:ffffc9000c2bbc68 EFLAGS: 00010002
RAX: 0000000000000009 RBX: ffff888c0af94c00 RCX: ffffffff81e12500
RDX: 000000000000002e RSI: ffff888c0af94c00 RDI: ffff888c10b22600
RBP: ffffc9000c2bbd08 R08: 0000000000000009 R09: 0000000000000078
R10: ffffffff81e12440 R11: ffffffff81e1236c R12: ffff888bc8932600
R13: ffff888c0af94eb8 R14: ffff888c10b22600 R15: ffff888bc8932600
FS: 00007fa58ac55700(0000) GS:ffff888c10b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa58b523230 CR3: 0000000bf44ab003 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
? intel_pstate_update_util_hwp+0x13/0x170
rt_mutex_setprio+0x1cc/0x4b0
task_blocks_on_rt_mutex+0x225/0x260
rt_spin_lock_slowlock_locked+0xab/0x2d0
rt_spin_lock_slowlock+0x50/0x80
hrtimer_grab_expiry_lock+0x20/0x30
hrtimer_cancel+0x13/0x30
do_nanosleep+0xa0/0x150
hrtimer_nanosleep+0xe1/0x230
? __hrtimer_init_sleeper+0x60/0x60
__x64_sys_nanosleep+0x8d/0xa0
do_syscall_64+0x4a/0x100
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7fa58b52330d
...
---[ end trace 0000000000000002 ]—
He also provided a simple reproducer creating the situation below:
So the execution order of locking steps are the following
(N1 and N2 are non-deadline tasks. D1 is a deadline task. M1 and M2
are mutexes that are enabled * with priority inheritance.)
Time moves forward as this timeline goes down:
N1 N2 D1
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Lock(M1) | |
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| Lock(M2) |
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| Lock(M1) |
| (!!bug triggered!) |
Daniel reported a similar situation as well, by just letting ksoftirqd
run with DEADLINE (and eventually block on a mutex).
Problem is that boosted entities (Priority Inheritance) use static
DEADLINE parameters of the top priority waiter. However, there might be
cases where top waiter could be a non-DEADLINE entity that is currently
boosted by a DEADLINE entity from a different lock chain (i.e., nested
priority chains involving entities of non-DEADLINE classes). In this
case, top waiter static DEADLINE parameters could be null (initialized
to 0 at fork()) and replenish_dl_entity() would hit a BUG().
Fix this by keeping track of the original donor and using its parameters
when a task is boosted.
Reported-by: Glenn Elliott <glenn@aurora.tech>
Reported-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Link: https://lkml.kernel.org/r/20201117061432.517340-1-juri.lelli@redhat.com
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schedule() ttwu()
deactivate_task(); if (p->on_rq && ...) // false
atomic_dec(&task_rq(p)->nr_iowait);
if (prev->in_iowait)
atomic_inc(&rq->nr_iowait);
Allows nr_iowait to be decremented before it gets incremented,
resulting in more dodgy IO-wait numbers than usual.
Note that because we can now do ttwu_queue_wakelist() before
p->on_cpu==0, we lose the natural ordering and have to further delay
the decrement.
Fixes: c6e7bd7afaeb ("sched/core: Optimize ttwu() spinning on p->on_cpu")
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Link: https://lkml.kernel.org/r/20201117093829.GD3121429@hirez.programming.kicks-ass.net
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enqueue_task_fair() attempts to skip the overutilized update for new
tasks as their util_avg is not accurate yet. However, the flag we check
to do so is overwritten earlier on in the function, which makes the
condition pretty much a nop.
Fix this by saving the flag early on.
Fixes: 2802bf3cd936 ("sched/fair: Add over-utilization/tipping point indicator")
Reported-by: Rick Yiu <rickyiu@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20201112111201.2081902-1-qperret@google.com
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
"A set of scheduler fixes:
- Address a load balancer regression by making the load balancer use
the same logic as the wakeup path to spread tasks in the LLC domain
- Prefer the CPU on which a task run last over the local CPU in the
fast wakeup path for asymmetric CPU capacity systems to align with
the symmetric case. This ensures more locality and prevents massive
migration overhead on those asymetric systems
- Fix a memory corruption bug in the scheduler debug code caused by
handing a modified buffer pointer to kfree()"
* tag 'sched-urgent-2020-11-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/debug: Fix memory corruption caused by multiple small reads of flags
sched/fair: Prefer prev cpu in asymmetric wakeup path
sched/fair: Ensure tasks spreading in LLC during LB
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Reading /proc/sys/kernel/sched_domain/cpu*/domain0/flags mutliple times
with small reads causes oopses with slub corruption issues because the kfree is
free'ing an offset from a previous allocation. Fix this by adding in a new
pointer 'buf' for the allocation and kfree and use the temporary pointer tmp
to handle memory copies of the buf offsets.
Fixes: 5b9f8ff7b320 ("sched/debug: Output SD flag names rather than their values")
Reported-by: Jeff Bastian <jbastian@redhat.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20201029151103.373410-1-colin.king@canonical.com
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During fast wakeup path, scheduler always check whether local or prev
cpus are good candidates for the task before looking for other cpus in
the domain. With commit b7a331615d25 ("sched/fair: Add asymmetric CPU
capacity wakeup scan") the heterogenous system gains a dedicated path
but doesn't try to reuse prev cpu whenever possible. If the previous
cpu is idle and belong to the LLC domain, we should check it 1st
before looking for another cpu because it stays one of the best
candidate and this also stabilizes task placement on the system.
This change aligns asymmetric path behavior with symmetric one and reduces
cases where the task migrates across all cpus of the sd_asym_cpucapacity
domains at wakeup.
This change does not impact normal EAS mode but only the overloaded case or
when EAS is not used.
- On hikey960 with performance governor (EAS disable)
./perf bench sched pipe -T -l 50000
mainline w/ patch
# migrations 999364 0
ops/sec 149313(+/-0.28%) 182587(+/- 0.40) +22%
- On hikey with performance governor
./perf bench sched pipe -T -l 50000
mainline w/ patch
# migrations 0 0
ops/sec 47721(+/-0.76%) 47899(+/- 0.56) +0.4%
According to test on hikey, the patch doesn't impact symmetric system
compared to current implementation (only tested on arm64)
Also read the uclamped value of task's utilization at most twice instead
instead each time we compare task's utilization with cpu's capacity.
Fixes: b7a331615d25 ("sched/fair: Add asymmetric CPU capacity wakeup scan")
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20201029161824.26389-1-vincent.guittot@linaro.org
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schbench shows latency increase for 95 percentile above since:
commit 0b0695f2b34a ("sched/fair: Rework load_balance()")
Align the behavior of the load balancer with the wake up path, which tries
to select an idle CPU which belongs to the LLC for a waking task.
calculate_imbalance() will use nr_running instead of the spare
capacity when CPUs share resources (ie cache) at the domain level. This
will ensure a better spread of tasks on idle CPUs.
Running schbench on a hikey (8cores arm64) shows the problem:
tip/sched/core :
schbench -m 2 -t 4 -s 10000 -c 1000000 -r 10
Latency percentiles (usec)
50.0th: 33
75.0th: 45
90.0th: 51
95.0th: 4152
*99.0th: 14288
99.5th: 14288
99.9th: 14288
min=0, max=14276
tip/sched/core + patch :
schbench -m 2 -t 4 -s 10000 -c 1000000 -r 10
Latency percentiles (usec)
50.0th: 34
75.0th: 47
90.0th: 52
95.0th: 78
*99.0th: 94
99.5th: 94
99.9th: 94
min=0, max=94
Fixes: 0b0695f2b34a ("sched/fair: Rework load_balance()")
Reported-by: Chris Mason <clm@fb.com>
Suggested-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Rik van Riel <riel@surriel.com>
Tested-by: Rik van Riel <riel@surriel.com>
Link: https://lkml.kernel.org/r/20201102102457.28808-1-vincent.guittot@linaro.org
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A new cpufreq governor flag will be added subsequently, so replace
the bool dynamic_switching fleid in struct cpufreq_governor with a
flags field and introduce CPUFREQ_GOV_DYNAMIC_SWITCHING to set for
the "dynamic switching" governors instead of it.
No intentional functional impact.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
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The cpufreq policy's frequency limits (min/max) can get changed at any
point of time, while schedutil is trying to update the next frequency.
Though the schedutil governor has necessary locking and support in place
to make sure we don't miss any of those updates, there is a corner case
where the governor will find that the CPU is already running at the
desired frequency and so may skip an update.
For example, consider that the CPU can run at 1 GHz, 1.2 GHz and 1.4 GHz
and is running at 1 GHz currently. Schedutil tries to update the
frequency to 1.2 GHz, during this time the policy limits get changed as
policy->min = 1.4 GHz. As schedutil (and cpufreq core) does clamp the
frequency at various instances, we will eventually set the frequency to
1.4 GHz, while we will save 1.2 GHz in sg_policy->next_freq.
Now lets say the policy limits get changed back at this time with
policy->min as 1 GHz. The next time schedutil is invoked by the
scheduler, we will reevaluate the next frequency (because
need_freq_update will get set due to limits change event) and lets say
we want to set the frequency to 1.2 GHz again. At this point
sugov_update_next_freq() will find the next_freq == current_freq and
will abort the update, while the CPU actually runs at 1.4 GHz.
Until now need_freq_update was used as a flag to indicate that the
policy's frequency limits have changed, and that we should consider the
new limits while reevaluating the next frequency.
This patch fixes the above mentioned issue by extending the purpose of
the need_freq_update flag. If this flag is set now, the schedutil
governor will not try to abort a frequency change even if next_freq ==
current_freq.
As similar behavior is required in the case of
CPUFREQ_NEED_UPDATE_LIMITS flag as well, need_freq_update will never be
set to false if that flag is set for the driver.
We also don't need to consider the need_freq_update flag in
sugov_update_single() anymore to handle the special case of busy CPU, as
we won't abort a frequency update anymore.
Reported-by: zhuguangqing <zhuguangqing@xiaomi.com>
Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Rearrange code to avoid a branch ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Because sugov_update_next_freq() may skip a frequency update even if
the need_freq_update flag has been set for the policy at hand, policy
limits updates may not take effect as expected.
For example, if the intel_pstate driver operates in the passive mode
with HWP enabled, it needs to update the HWP min and max limits when
the policy min and max limits change, respectively, but that may not
happen if the target frequency does not change along with the limit
at hand. In particular, if the policy min is changed first, causing
the target frequency to be adjusted to it, and the policy max limit
is changed later to the same value, the HWP max limit will not be
updated to follow it as expected, because the target frequency is
still equal to the policy min limit and it will not change until
that limit is updated.
To address this issue, modify get_next_freq() to let the driver
callback run if the CPUFREQ_NEED_UPDATE_LIMITS cpufreq driver flag
is set regardless of whether or not the new frequency to set is
equal to the previous one.
Fixes: f6ebbcf08f37 ("cpufreq: intel_pstate: Implement passive mode with HWP enabled")
Reported-by: Zhang Rui <rui.zhang@intel.com>
Tested-by: Zhang Rui <rui.zhang@intel.com>
Cc: 5.9+ <stable@vger.kernel.org> # 5.9+: 1c534352f47f cpufreq: Introduce CPUFREQ_NEED_UPDATE_LIMITS ...
Cc: 5.9+ <stable@vger.kernel.org> # 5.9+: a62f68f5ca53 cpufreq: Introduce cpufreq_driver_test_flags()
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Use a more generic form for __section that requires quotes to avoid
complications with clang and gcc differences.
Remove the quote operator # from compiler_attributes.h __section macro.
Convert all unquoted __section(foo) uses to quoted __section("foo").
Also convert __attribute__((section("foo"))) uses to __section("foo")
even if the __attribute__ has multiple list entry forms.
Conversion done using the script at:
https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@gooogle.com>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
"Two scheduler fixes:
- A trivial build fix for sched_feat() to compile correctly with
CONFIG_JUMP_LABEL=n
- Replace a zero lenght array with a flexible array"
* tag 'sched-urgent-2020-10-25' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/features: Fix !CONFIG_JUMP_LABEL case
sched: Replace zero-length array with flexible-array
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Commit:
765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds")
made sched features static for !CONFIG_SCHED_DEBUG configurations, but
overlooked the CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL cases.
For the latter echoing changes to /sys/kernel/debug/sched_features has
the nasty effect of effectively changing what sched_features reports,
but without actually changing the scheduler behaviour (since different
translation units get different sysctl_sched_features).
Fix CONFIG_SCHED_DEBUG=y and !CONFIG_JUMP_LABEL configurations by properly
restructuring ifdefs.
Fixes: 765cc3a4b224e ("sched/core: Optimize sched_feat() for !CONFIG_SCHED_DEBUG builds")
Co-developed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Patrick Bellasi <patrick.bellasi@matbug.net>
Reviewed-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lore.kernel.org/r/20201013053114.160628-1-juri.lelli@redhat.com
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In the following commit:
04f5c362ec6d: ("sched/fair: Replace zero-length array with flexible-array")
a zero-length array cpumask[0] has been replaced with cpumask[].
But there is still a cpumask[0] in 'struct sched_group_capacity'
which was missed.
The point of using [] instead of [0] is that with [] the compiler will
generate a build warning if it isn't the last member of a struct.
[ mingo: Rewrote the changelog. ]
Signed-off-by: zhuguangqing <zhuguangqing@xiaomi.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20201014140220.11384-1-zhuguangqing83@gmail.com
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more power management updates from Rafael Wysocki:
"First of all, the adaptive voltage scaling (AVS) drivers go to new
platform-specific locations as planned (this part was reported to have
merge conflicts against the new arm-soc updates in linux-next).
In addition to that, there are some fixes (intel_idle, intel_pstate,
RAPL, acpi_cpufreq), the addition of on/off notifiers and idle state
accounting support to the generic power domains (genpd) code and some
janitorial changes all over.
Specifics:
- Move the AVS drivers to new platform-specific locations and get rid
of the drivers/power/avs directory (Ulf Hansson).
- Add on/off notifiers and idle state accounting support to the
generic power domains (genpd) framework (Ulf Hansson, Lina Iyer).
- Ulf will maintain the PM domain part of cpuidle-psci (Ulf Hansson).
- Make intel_idle disregard ACPI _CST if it cannot use the data
returned by that method (Mel Gorman).
- Modify intel_pstate to avoid leaving useless sysfs directory
structure behind if it cannot be registered (Chen Yu).
- Fix domain detection in the RAPL power capping driver and prevent
it from failing to enumerate the Psys RAPL domain (Zhang Rui).
- Allow acpi-cpufreq to use ACPI _PSD information with Family 19 and
later AMD chips (Wei Huang).
- Update the driver assumptions comment in intel_idle and fix a
kerneldoc comment in the runtime PM framework (Alexander Monakov,
Bean Huo).
- Avoid unnecessary resets of the cached frequency in the schedutil
cpufreq governor to reduce overhead (Wei Wang).
- Clean up the cpufreq core a bit (Viresh Kumar).
- Make assorted minor janitorial changes (Daniel Lezcano, Geert
Uytterhoeven, Hubert Jasudowicz, Tom Rix).
- Clean up and optimize the cpupower utility somewhat (Colin Ian
King, Martin Kaistra)"
* tag 'pm-5.10-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (23 commits)
PM: sleep: remove unreachable break
PM: AVS: Drop the avs directory and the corresponding Kconfig
PM: AVS: qcom-cpr: Move the driver to the qcom specific drivers
PM: runtime: Fix typo in pm_runtime_set_active() helper comment
PM: domains: Fix build error for genpd notifiers
powercap: Fix typo in Kconfig "Plance" -> "Plane"
cpufreq: schedutil: restore cached freq when next_f is not changed
acpi-cpufreq: Honor _PSD table setting on new AMD CPUs
PM: AVS: smartreflex Move driver to soc specific drivers
PM: AVS: rockchip-io: Move the driver to the rockchip specific drivers
PM: domains: enable domain idle state accounting
PM: domains: Add curly braces to delimit comment + statement block
PM: domains: Add support for PM domain on/off notifiers for genpd
powercap/intel_rapl: enumerate Psys RAPL domain together with package RAPL domain
powercap/intel_rapl: Fix domain detection
intel_idle: Ignore _CST if control cannot be taken from the platform
cpuidle: Remove pointless stub
intel_idle: mention assumption that WBINVD is not needed
MAINTAINERS: Add section for cpuidle-psci PM domain
cpufreq: intel_pstate: Delete intel_pstate sysfs if failed to register the driver
...
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We have the raw cached freq to reduce the chance in calling cpufreq
driver where it could be costly in some arch/SoC.
Currently, the raw cached freq is reset in sugov_update_single() when
it avoids frequency reduction (which is not desirable sometimes), but
it is better to restore the previous value of it in that case,
because it may not change in the next cycle and it is not necessary
to change the CPU frequency then.
Adapted from https://android-review.googlesource.com/1352810/
Signed-off-by: Wei Wang <wvw@google.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
[ rjw: Subject edit and changelog rewrite ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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A previous commit changed the notification mode from true/false to an
int, allowing notify-no, notify-yes, or signal-notify. This was
backwards compatible in the sense that any existing true/false user
would translate to either 0 (on notification sent) or 1, the latter
which mapped to TWA_RESUME. TWA_SIGNAL was assigned a value of 2.
Clean this up properly, and define a proper enum for the notification
mode. Now we have:
- TWA_NONE. This is 0, same as before the original change, meaning no
notification requested.
- TWA_RESUME. This is 1, same as before the original change, meaning
that we use TIF_NOTIFY_RESUME.
- TWA_SIGNAL. This uses TIF_SIGPENDING/JOBCTL_TASK_WORK for the
notification.
Clean up all the callers, switching their 0/1/false/true to using the
appropriate TWA_* mode for notifications.
Fixes: e91b48162332 ("task_work: teach task_work_add() to do signal_wake_up()")
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull power management updates from Rafael Wysocki:
"These rework the collection of cpufreq statistics to allow it to take
place if fast frequency switching is enabled in the governor, rework
the frequency invariance handling in the cpufreq core and drivers, add
new hardware support to a couple of cpufreq drivers, fix a number of
assorted issues and clean up the code all over.
Specifics:
- Rework cpufreq statistics collection to allow it to take place when
fast frequency switching is enabled in the governor (Viresh Kumar).
- Make the cpufreq core set the frequency scale on behalf of the
driver and update several cpufreq drivers accordingly (Ionela
Voinescu, Valentin Schneider).
- Add new hardware support to the STI and qcom cpufreq drivers and
improve them (Alain Volmat, Manivannan Sadhasivam).
- Fix multiple assorted issues in cpufreq drivers (Jon Hunter,
Krzysztof Kozlowski, Matthias Kaehlcke, Pali Rohár, Stephan
Gerhold, Viresh Kumar).
- Fix several assorted issues in the operating performance points
(OPP) framework (Stephan Gerhold, Viresh Kumar).
- Allow devfreq drivers to fetch devfreq instances by DT enumeration
instead of using explicit phandles and modify the devfreq core code
to support driver-specific devfreq DT bindings (Leonard Crestez,
Chanwoo Choi).
- Improve initial hardware resetting in the tegra30 devfreq driver
and clean up the tegra cpuidle driver (Dmitry Osipenko).
- Update the cpuidle core to collect state entry rejection statistics
and expose them via sysfs (Lina Iyer).
- Improve the ACPI _CST code handling diagnostics (Chen Yu).
- Update the PSCI cpuidle driver to allow the PM domain
initialization to occur in the OSI mode as well as in the PC mode
(Ulf Hansson).
- Rework the generic power domains (genpd) core code to allow domain
power off transition to be aborted in the absence of the "power
off" domain callback (Ulf Hansson).
- Fix two suspend-to-idle issues in the ACPI EC driver (Rafael
Wysocki).
- Fix the handling of timer_expires in the PM-runtime framework on
32-bit systems and the handling of device links in it (Grygorii
Strashko, Xiang Chen).
- Add IO requests batching support to the hibernate image saving and
reading code and drop a bogus get_gendisk() from there (Xiaoyi
Chen, Christoph Hellwig).
- Allow PCIe ports to be put into the D3cold power state if they are
power-manageable via ACPI (Lukas Wunner).
- Add missing header file include to a power capping driver (Pujin
Shi).
- Clean up the qcom-cpr AVS driver a bit (Liu Shixin).
- Kevin Hilman steps down as designated reviwer of adaptive voltage
scaling (AVS) drivers (Kevin Hilman)"
* tag 'pm-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (65 commits)
cpufreq: stats: Fix string format specifier mismatch
arm: disable frequency invariance for CONFIG_BL_SWITCHER
cpufreq,arm,arm64: restructure definitions of arch_set_freq_scale()
cpufreq: stats: Add memory barrier to store_reset()
cpufreq: schedutil: Simplify sugov_fast_switch()
ACPI: EC: PM: Drop ec_no_wakeup check from acpi_ec_dispatch_gpe()
ACPI: EC: PM: Flush EC work unconditionally after wakeup
PCI/ACPI: Whitelist hotplug ports for D3 if power managed by ACPI
PM: hibernate: remove the bogus call to get_gendisk() in software_resume()
cpufreq: Move traces and update to policy->cur to cpufreq core
cpufreq: stats: Enable stats for fast-switch as well
cpufreq: stats: Mark few conditionals with unlikely()
cpufreq: stats: Remove locking
cpufreq: stats: Defer stats update to cpufreq_stats_record_transition()
PM: domains: Allow to abort power off when no ->power_off() callback
PM: domains: Rename power state enums for genpd
PM / devfreq: tegra30: Improve initial hardware resetting
PM / devfreq: event: Change prototype of devfreq_event_get_edev_by_phandle function
PM / devfreq: Change prototype of devfreq_get_devfreq_by_phandle function
PM / devfreq: Add devfreq_get_devfreq_by_node function
...
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Drop a redundant local variable definition from sugov_fast_switch()
and rearrange the code in there to avoid the redundant logical
negation.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
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The cpufreq core handles the updates to policy->cur and recording of
cpufreq trace events for all the governors except schedutil's fast
switch case.
Move that as well to cpufreq core for consistency and readability.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
- reorganize & clean up the SD* flags definitions and add a bunch of
sanity checks. These new checks caught quite a few bugs or at least
inconsistencies, resulting in another set of patches.
- rseq updates, add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
- add a new tracepoint to improve CPU capacity tracking
- improve overloaded SMP system load-balancing behavior
- tweak SMT balancing
- energy-aware scheduling updates
- NUMA balancing improvements
- deadline scheduler fixes and improvements
- CPU isolation fixes
- misc cleanups, simplifications and smaller optimizations
* tag 'sched-core-2020-10-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (42 commits)
sched/deadline: Unthrottle PI boosted threads while enqueuing
sched/debug: Add new tracepoint to track cpu_capacity
sched/fair: Tweak pick_next_entity()
rseq/selftests: Test MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
rseq/selftests,x86_64: Add rseq_offset_deref_addv()
rseq/membarrier: Add MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ
sched/fair: Use dst group while checking imbalance for NUMA balancer
sched/fair: Reduce busy load balance interval
sched/fair: Minimize concurrent LBs between domain level
sched/fair: Reduce minimal imbalance threshold
sched/fair: Relax constraint on task's load during load balance
sched/fair: Remove the force parameter of update_tg_load_avg()
sched/fair: Fix wrong cpu selecting from isolated domain
sched: Remove unused inline function uclamp_bucket_base_value()
sched/rt: Disable RT_RUNTIME_SHARE by default
sched/deadline: Fix stale throttling on de-/boosted tasks
sched/numa: Use runnable_avg to classify node
sched/topology: Move sd_flag_debug out of #ifdef CONFIG_SYSCTL
MAINTAINERS: Add myself as SCHED_DEADLINE reviewer
sched/topology: Move SD_DEGENERATE_GROUPS_MASK out of linux/sched/topology.h
...
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