Re: [PATCH v3 1/1] cgroup: make per-cgroup pressure stall tracking configurable

[Peter Zijlstra]

On Mon, May 24, 2021 at 12:53:39PM -0700, Suren Baghdasaryan wrote:
> PSI accounts stalls for each cgroup separately and aggregates it at each
> level of the hierarchy. This causes additional overhead with psi_avgs_work
> being called for each cgroup in the hierarchy. psi_avgs_work has been
> highly optimized, however on systems with large number of cgroups the
> overhead becomes noticeable.
> Systems which use PSI only at the system level could avoid this overhead
> if PSI can be configured to skip per-cgroup stall accounting.
> Add "cgroup_disable=pressure" kernel command-line option to allow
> requesting system-wide only pressure stall accounting. When set, it
> keeps system-wide accounting under /proc/pressure/ but skips accounting
> for individual cgroups and does not expose PSI nodes in cgroup hierarchy.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>

>  kernel/sched/psi.c                            | 30 +++++++-----

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>