Re: [PATCH v3 4/4] sched: adjust sleeper credit for SCHED_IDLE entities

[Josh Don]

On Tue, Aug 24, 2021 at 1:16 AM Jiang Biao <benbjiang@xxxxxxxxx> wrote:
>
> Hi,
>
> On Fri, 20 Aug 2021 at 09:06, Josh Don <joshdon@xxxxxxxxxx> wrote:
> >
> > Give reduced sleeper credit to SCHED_IDLE entities. As a result, woken
> > SCHED_IDLE entities will take longer to preempt normal entities.
> >
> > The benefit of this change is to make it less likely that a newly woken
> > SCHED_IDLE entity will preempt a short-running normal entity before it
> > blocks.
> >
> > We still give a small sleeper credit to SCHED_IDLE entities, so that
> > idle<->idle competition retains some fairness.
> >
> > Example: With HZ=1000, spawned four threads affined to one cpu, one of
> > which was set to SCHED_IDLE. Without this patch, wakeup latency for the
> > SCHED_IDLE thread was ~1-2ms, with the patch the wakeup latency was
> > ~5ms.
> >
> > Signed-off-by: Josh Don <joshdon@xxxxxxxxxx>
> Tried to push a similar patch before, but failed. :)
> https://lkml.org/lkml/2020/8/20/1773
> Please pick my Reviewed-by if you don't mind,
> Reviewed-by: Jiang Biao <benbjiang@xxxxxxxxxxx>

Done, thanks :)