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| author |   Johannes Weiner <hannes@cmpxchg.org> | 2020-03-16 15:13:31 -0400 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2020-03-20 13:06:18 +0100 |
| commit | b05e75d611380881e73edc58a20fd8c6bb71720b (patch) | |
| tree | 3d641b57b42e934d7518f22a13f3a74cd76f6ff7 /kernel/sched/core.c | |
| parent | sched/core: Distribute tasks within affinity masks (diff) | |
| download | wireguard-linux-b05e75d611380881e73edc58a20fd8c6bb71720b.tar.xz wireguard-linux-b05e75d611380881e73edc58a20fd8c6bb71720b.zip | |
psi: Fix cpu.pressure for cpu.max and competing cgroups
For simplicity, cpu pressure is defined as having more than one
runnable task on a given CPU. This works on the system-level, but it
has limitations in a cgrouped reality: When cpu.max is in use, it
doesn't capture the time in which a task is not executing on the CPU
due to throttling. Likewise, it doesn't capture the time in which a
competing cgroup is occupying the CPU - meaning it only reflects
cgroup-internal competitive pressure, not outside pressure.
Enable tracking of currently executing tasks, and then change the
definition of cpu pressure in a cgroup from
NR_RUNNING > 1
to
NR_RUNNING > ON_CPU
which will capture the effects of cpu.max as well as competition from
outside the cgroup.
After this patch, a cgroup running `stress -c 1` with a cpu.max
setting of 5000 10000 shows ~50% continuous CPU pressure.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200316191333.115523-2-hannes@cmpxchg.org
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 014d4f793313..c1f923d647ee 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4091,6 +4091,8 @@ static void __sched notrace __schedule(bool preempt) */ ++*switch_count; + psi_sched_switch(prev, next, !task_on_rq_queued(prev)); + trace_sched_switch(preempt, prev, next); /* Also unlocks the rq: */ |