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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-16 17:25:49 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-16 17:25:49 -0700
commit7e67a859997aad47727aff9c5a32e160da079ce3 (patch)
tree96f53425c2834de5b3276d7598782ab6412e4d5e /Documentation/admin-guide
parent772c1d06bd402f7ee72c61a18c2db74cd74b6758 (diff)
parent563c4f85f9f0d63b712081d5b4522152cdcb8b6b (diff)
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Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar: - MAINTAINERS: Add Mark Rutland as perf submaintainer, Juri Lelli and Vincent Guittot as scheduler submaintainers. Add Dietmar Eggemann, Steven Rostedt, Ben Segall and Mel Gorman as scheduler reviewers. As perf and the scheduler is getting bigger and more complex, document the status quo of current responsibilities and interests, and spread the review pain^H^H^H^H fun via an increase in the Cc: linecount generated by scripts/get_maintainer.pl. :-) - Add another series of patches that brings the -rt (PREEMPT_RT) tree closer to mainline: split the monolithic CONFIG_PREEMPT dependencies into a new CONFIG_PREEMPTION category that will allow the eventual introduction of CONFIG_PREEMPT_RT. Still a few more hundred patches to go though. - Extend the CPU cgroup controller with uclamp.min and uclamp.max to allow the finer shaping of CPU bandwidth usage. - Micro-optimize energy-aware wake-ups from O(CPUS^2) to O(CPUS). - Improve the behavior of high CPU count, high thread count applications running under cpu.cfs_quota_us constraints. - Improve balancing with SCHED_IDLE (SCHED_BATCH) tasks present. - Improve CPU isolation housekeeping CPU allocation NUMA locality. - Fix deadline scheduler bandwidth calculations and logic when cpusets rebuilds the topology, or when it gets deadline-throttled while it's being offlined. - Convert the cpuset_mutex to percpu_rwsem, to allow it to be used from setscheduler() system calls without creating global serialization. Add new synchronization between cpuset topology-changing events and the deadline acceptance tests in setscheduler(), which were broken before. - Rework the active_mm state machine to be less confusing and more optimal. - Rework (simplify) the pick_next_task() slowpath. - Improve load-balancing on AMD EPYC systems. - ... and misc cleanups, smaller fixes and improvements - please see the Git log for more details. * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (53 commits) sched/psi: Correct overly pessimistic size calculation sched/fair: Speed-up energy-aware wake-ups sched/uclamp: Always use 'enum uclamp_id' for clamp_id values sched/uclamp: Update CPU's refcount on TG's clamp changes sched/uclamp: Use TG's clamps to restrict TASK's clamps sched/uclamp: Propagate system defaults to the root group sched/uclamp: Propagate parent clamps sched/uclamp: Extend CPU's cgroup controller sched/topology: Improve load balancing on AMD EPYC systems arch, ia64: Make NUMA select SMP sched, perf: MAINTAINERS update, add submaintainers and reviewers sched/fair: Use rq_lock/unlock in online_fair_sched_group cpufreq: schedutil: fix equation in comment sched: Rework pick_next_task() slow-path sched: Allow put_prev_task() to drop rq->lock sched/fair: Expose newidle_balance() sched: Add task_struct pointer to sched_class::set_curr_task sched: Rework CPU hotplug task selection sched/{rt,deadline}: Fix set_next_task vs pick_next_task sched: Fix kerneldoc comment for ia64_set_curr_task ...
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst34
1 files changed, 34 insertions, 0 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 3b29005aa981..5f1c266131b0 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -951,6 +951,13 @@ controller implements weight and absolute bandwidth limit models for
normal scheduling policy and absolute bandwidth allocation model for
realtime scheduling policy.
+In all the above models, cycles distribution is defined only on a temporal
+base and it does not account for the frequency at which tasks are executed.
+The (optional) utilization clamping support allows to hint the schedutil
+cpufreq governor about the minimum desired frequency which should always be
+provided by a CPU, as well as the maximum desired frequency, which should not
+be exceeded by a CPU.
+
WARNING: cgroup2 doesn't yet support control of realtime processes and
the cpu controller can only be enabled when all RT processes are in
the root cgroup. Be aware that system management software may already
@@ -1016,6 +1023,33 @@ All time durations are in microseconds.
Shows pressure stall information for CPU. See
Documentation/accounting/psi.rst for details.
+ cpu.uclamp.min
+ A read-write single value file which exists on non-root cgroups.
+ The default is "0", i.e. no utilization boosting.
+
+ The requested minimum utilization (protection) as a percentage
+ rational number, e.g. 12.34 for 12.34%.
+
+ This interface allows reading and setting minimum utilization clamp
+ values similar to the sched_setattr(2). This minimum utilization
+ value is used to clamp the task specific minimum utilization clamp.
+
+ The requested minimum utilization (protection) is always capped by
+ the current value for the maximum utilization (limit), i.e.
+ `cpu.uclamp.max`.
+
+ cpu.uclamp.max
+ A read-write single value file which exists on non-root cgroups.
+ The default is "max". i.e. no utilization capping
+
+ The requested maximum utilization (limit) as a percentage rational
+ number, e.g. 98.76 for 98.76%.
+
+ This interface allows reading and setting maximum utilization clamp
+ values similar to the sched_setattr(2). This maximum utilization
+ value is used to clamp the task specific maximum utilization clamp.
+
+
Memory
------