Re: [PATCH 1/9] sched/psi: fix periodic aggregation shut off

Johannes Weiner
2022-07-25T15:34:39Z

On Thu, Jul 21, 2022 at 12:04:31PM +0800, Chengming Zhou wrote:
> We don't want to wake periodic aggregation work back up if the
> task change is the aggregation worker itself going to sleep, or
> we'll ping-pong forever.
>
> Previously, we would use psi_task_change() in psi_dequeue() when
> task going to sleep, so this check was put in psi_task_change().
>
> But commit 4117cebf1a9f ("psi: Optimize task switch inside shared cgroups")
> defer task sleep handling to psi_task_switch(), won't go through
> psi_task_change() anymore.
>
> So this patch move this check to psi_task_switch(). Note for defer sleep
> case, we should wake periodic avgs work for common ancestors groups,
> since those groups have next task sched_in.
>
> Fixes: 4117cebf1a9f ("psi: Optimize task switch inside shared cgroups")
> Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>

Good catch!

Acked-by: Johannes Weiner <hannes@cmpxchg.org>