linux-kernel - Re: [PATCH v2] psi: Fix avg trigger being fired unexpectedly.

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Date: Tue, 26 Mar 2024 17:49:45 +0000
From: Suren Baghdasaryan <surenb@...gle.com>
To: "levi.yun" <ppbuk5246@...il.com>
Cc: hannes@...xchg.org, peterz@...radead.org, mingo@...hat.com, 
	juri.lelli@...hat.com, vincent.guittot@...aro.org, dietmar.eggemann@....com, 
	rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com, 
	vschneid@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] psi: Fix avg trigger being fired unexpectedly.

On Tue, Mar 12, 2024 at 6:10 AM levi.yun <ppbuk5246@...il.com> wrote:
>
> Gentle ping..
>
> On Mon, Feb 26, 2024 at 09:12:37PM +0000, Levi Yun wrote:
> > commit 915a087e4c473("psi: Fix trigger being fired unexpectedly at initial")
> > fixes unexpected event fired when group->total accumulated for PSI_POLL.
> > But, for PSI_AVGS, win->value should be initialized with group->total[PSI_AVGS].
> > Moreover, to get exact initial value for win->value, it should be set
> > under each trigger lock to avoid concurrent changes to group->total[].
> >
> > Signed-off-by: Levi Yun <ppbuk5246@...il.com>
> > Acked-by: Suren Baghdasaryan <surenb@...gle.com>

Hi Peter,
Could you please pull this patch into your tree? I don't see it in any
tree, so I think you missed it.
Thanks,
Suren.

> > ---
> > v2: Fix commit message.
> > ---
> >  kernel/sched/psi.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
> > index 7b4aa5809c0f..e7f66ab2ad3e 100644
> > --- a/kernel/sched/psi.c
> > +++ b/kernel/sched/psi.c
> > @@ -1323,9 +1323,6 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf,
> >       t->state = state;
> >       t->threshold = threshold_us * NSEC_PER_USEC;
> >       t->win.size = window_us * NSEC_PER_USEC;
> > -     window_reset(&t->win, sched_clock(),
> > -                     group->total[PSI_POLL][t->state], 0);
> > -
> >       t->event = 0;
> >       t->last_event_time = 0;
> >       t->of = of;
> > @@ -1336,6 +1333,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf,
> >
> >       if (privileged) {
> >               mutex_lock(&group->rtpoll_trigger_lock);
> > +             window_reset(&t->win, sched_clock(),
> > +                             group->total[PSI_POLL][t->state], 0);
> >
> >               if (!rcu_access_pointer(group->rtpoll_task)) {
> >                       struct task_struct *task;
> > @@ -1361,6 +1360,9 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group, char *buf,
> >       } else {
> >               mutex_lock(&group->avgs_lock);
> >
> > +             window_reset(&t->win, sched_clock(),
> > +                             group->total[PSI_AVGS][t->state], 0);
> > +
> >               list_add(&t->node, &group->avg_triggers);
> >               group->avg_nr_triggers[t->state]++;
> >
> > --
> > 2.39.2