Hello. On Sat, Jan 25, 2025 at 01:25:12PM +0800, Abel Wu <wuyun.abel@xxxxxxxxxxxxx> wrote: > The per-task and per-cpu accounting have already been tracked by > t->sched_info.run_delay and rq->rq_sched_info.run_delay respectively. > Extends this to also include cgroups. > > The PSI indicator, "some" of cpu.pressure, loses the insight into how > severely that cgroup is stalled. Say 100 tasks or just 1 task that gets > stalled at a certain point will show no difference in "some" pressure. > IOW "some" is a flat value that not weighted by the severity (e.g. # of > tasks). IIUC below are three examples of when "some" tasks are waiting for CPU: a) t1 |----| t2 |xx--| b) t1 |----| t2 |x---| t3 |-x--| c) t1 |----| t2 |xx--| t3 |xx--| (- means runnable on CPU, x means runnable waiting on RQ) Which pair from a), b), c) is indistinguishable via PSI? (Or can you please add your illustrative example?) And how do per-cgroup run_delay distinguishe those? Thanks, Michal
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