[PATCH] psi: Fix trigger being fired unexpectedly at initial

[PATCH] psi: Fix trigger being fired unexpectedly at initial

[Hailong Liu]

When a trigger being created, its win.start_value and win.start_time are
reset to zero. If group->total[PSI_POLL][t->state] has accumulated before,
this trigger will be fired unexpectedly in the next period, even if its
growth time does not reach its threshold.

So set the window of the new trigger to the current state value.

Signed-off-by: Hailong Liu <liuhailong@linux.alibaba.com>
---
 kernel/sched/psi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index a4fa3aadfcba..5a49a8c8783e 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1117,7 +1117,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 	t->state = state;
 	t->threshold = threshold_us * NSEC_PER_USEC;
 	t->win.size = window_us * NSEC_PER_USEC;
-	window_reset(&t->win, 0, 0, 0);
+	window_reset(&t->win, sched_clock(),
+			group->total[PSI_POLL][t->state], 0);
 
 	t->event = 0;
 	t->last_event_time = 0;
-- 
2.19.1.6.gb485710b

Re: [PATCH] psi: Fix trigger being fired unexpectedly at initial

[Suren Baghdasaryan]

On Thu, Mar 31, 2022 at 10:10 PM Hailong Liu
<liuhailong@linux.alibaba.com> wrote:
>
> When a trigger being created, its win.start_value and win.start_time are
> reset to zero. If group->total[PSI_POLL][t->state] has accumulated before,
> this trigger will be fired unexpectedly in the next period, even if its
> growth time does not reach its threshold.
>
> So set the window of the new trigger to the current state value.

Makes sense to me. Thanks!

>
> Signed-off-by: Hailong Liu <liuhailong@linux.alibaba.com>

Acked-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  kernel/sched/psi.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
> index a4fa3aadfcba..5a49a8c8783e 100644
> --- a/kernel/sched/psi.c
> +++ b/kernel/sched/psi.c
> @@ -1117,7 +1117,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
>         t->state = state;
>         t->threshold = threshold_us * NSEC_PER_USEC;
>         t->win.size = window_us * NSEC_PER_USEC;
> -       window_reset(&t->win, 0, 0, 0);
> +       window_reset(&t->win, sched_clock(),
> +                       group->total[PSI_POLL][t->state], 0);
>
>         t->event = 0;
>         t->last_event_time = 0;
> --
> 2.19.1.6.gb485710b
>

Re: [PATCH] psi: Fix trigger being fired unexpectedly at initial

[Peter Zijlstra]

On Fri, Apr 01, 2022 at 09:19:17AM -0700, Suren Baghdasaryan wrote:
> On Thu, Mar 31, 2022 at 10:10 PM Hailong Liu
> <liuhailong@linux.alibaba.com> wrote:
> >
> > When a trigger being created, its win.start_value and win.start_time are
> > reset to zero. If group->total[PSI_POLL][t->state] has accumulated before,
> > this trigger will be fired unexpectedly in the next period, even if its
> > growth time does not reach its threshold.
> >
> > So set the window of the new trigger to the current state value.
> 
> Makes sense to me. Thanks!
> 
> >
> > Signed-off-by: Hailong Liu <liuhailong@linux.alibaba.com>
> 
> Acked-by: Suren Baghdasaryan <surenb@google.com>

Thanks!

[tip: sched/core] psi: Fix trigger being fired unexpectedly at initial

[tip-bot2 for Hailong Liu]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     915a087e4c47334a2f7ba2a4092c4bade0873769
Gitweb:        https://git.kernel.org/tip/915a087e4c47334a2f7ba2a4092c4bade0873769
Author:        Hailong Liu <liuhailong@linux.alibaba.com>
AuthorDate:    Fri, 01 Apr 2022 13:10:11 +08:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 22 Apr 2022 12:14:06 +02:00

psi: Fix trigger being fired unexpectedly at initial

When a trigger being created, its win.start_value and win.start_time are
reset to zero. If group->total[PSI_POLL][t->state] has accumulated before,
this trigger will be fired unexpectedly in the next period, even if its
growth time does not reach its threshold.

So set the window of the new trigger to the current state value.

Signed-off-by: Hailong Liu <liuhailong@linux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Link: https://lore.kernel.org/r/1648789811-3788971-1-git-send-email-liuhailong@linux.alibaba.com
---
 kernel/sched/psi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index a4fa3aa..5a49a8c 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1117,7 +1117,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 	t->state = state;
 	t->threshold = threshold_us * NSEC_PER_USEC;
 	t->win.size = window_us * NSEC_PER_USEC;
-	window_reset(&t->win, 0, 0, 0);
+	window_reset(&t->win, sched_clock(),
+			group->total[PSI_POLL][t->state], 0);
 
 	t->event = 0;
 	t->last_event_time = 0;