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| author |   Chengming Zhou <zhouchengming@bytedance.com> | 2022-09-07 17:03:32 +0800 |
|---|---|---|
| committer |   Peter Zijlstra <peterz@infradead.org> | 2022-09-09 11:08:33 +0200 |
| commit | 34f26a15611afb03c33df6819359d36f5b382589 (patch) | |
| tree | 38765bb0112e0ba6c8f173d8a6a129bf0b9f92f0 /include/linux/psi_types.h | |
| parent | sched/psi: Cache parent psi_group to speed up group iteration (diff) | |
| download | linux-dev-34f26a15611afb03c33df6819359d36f5b382589.tar.xz linux-dev-34f26a15611afb03c33df6819359d36f5b382589.zip | |
sched/psi: Per-cgroup PSI accounting disable/re-enable interface
PSI accounts stalls for each cgroup separately and aggregates it
at each level of the hierarchy. This may cause non-negligible overhead
for some workloads when under deep level of the hierarchy.
commit 3958e2d0c34e ("cgroup: make per-cgroup pressure stall tracking configurable")
make PSI to skip per-cgroup stall accounting, only account system-wide
to avoid this each level overhead.
But for our use case, we also want leaf cgroup PSI stats accounted for
userspace adjustment on that cgroup, apart from only system-wide adjustment.
So this patch introduce a per-cgroup PSI accounting disable/re-enable
interface "cgroup.pressure", which is a read-write single value file that
allowed values are "0" and "1", the defaults is "1" so per-cgroup
PSI stats is enabled by default.
Implementation details:
It should be relatively straight-forward to disable and re-enable
state aggregation, time tracking, averaging on a per-cgroup level,
if we can live with losing history from while it was disabled.
I.e. the avgs will restart from 0, total= will have gaps.
But it's hard or complex to stop/restart groupc->tasks[] updates,
which is not implemented in this patch. So we always update
groupc->tasks[] and PSI_ONCPU bit in psi_group_change() even when
the cgroup PSI stats is disabled.
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lkml.kernel.org/r/20220907090332.2078-1-zhouchengming@bytedance.com
Diffstat (limited to '')
| -rw-r--r-- | include/linux/psi_types.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/linux/psi_types.h b/include/linux/psi_types.h index a0b746258c68..6e4372735068 100644 --- a/include/linux/psi_types.h +++ b/include/linux/psi_types.h @@ -152,6 +152,7 @@ struct psi_trigger { struct psi_group { struct psi_group *parent; + bool enabled; /* Protects data used by the aggregator */ struct mutex avgs_lock; @@ -194,6 +195,8 @@ struct psi_group { #else /* CONFIG_PSI */ +#define NR_PSI_RESOURCES 0 + struct psi_group { }; #endif /* CONFIG_PSI */ |