2023-04-17 08:13:18

by Yang Yang

[permalink] [raw]
Subject: [PATCH linux-next] sched/psi: avoid unnecessary resetting min update period when destroy trigger

From: Yang Yang <[email protected]>

Psi_group's poll_min_period is determined by the min window size of
psi_trigger when creating new triggers. While destroying a psi_trigger,
there is no need to reset poll_min_period if the destroying psi_trigger
not had the min windows size, since in this condition poll_min_period
will keep the same as before.

Signed-off-by: Yang Yang <[email protected]>
---
kernel/sched/psi.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 02e011cabe91..12869585cf89 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1359,11 +1359,16 @@ void psi_trigger_destroy(struct psi_trigger *t)
group->nr_triggers[t->state]--;
if (!group->nr_triggers[t->state])
group->poll_states &= ~(1 << t->state);
- /* reset min update period for the remaining triggers */
- list_for_each_entry(tmp, &group->triggers, node)
- period = min(period, div_u64(tmp->win.size,
- UPDATES_PER_WINDOW));
- group->poll_min_period = period;
+ /*
+ * Reset min update period for the remaining triggers iff the destroying
+ * trigger had the min window size.
+ */
+ if (group->poll_min_period == div_u64(t->win.size, UPDATES_PER_WINDOW)) {
+ list_for_each_entry(tmp, &group->triggers, node)
+ period = min(period, div_u64(tmp->win.size,
+ UPDATES_PER_WINDOW));
+ group->poll_min_period = period;
+ }
/* Destroy poll_task when the last trigger is destroyed */
if (group->poll_states == 0) {
group->polling_until = 0;
--
2.25.1


2023-04-17 19:08:50

by Suren Baghdasaryan

[permalink] [raw]
Subject: Re: [PATCH linux-next] sched/psi: avoid unnecessary resetting min update period when destroy trigger

On Mon, Apr 17, 2023 at 1:12 AM <[email protected]> wrote:
>
> From: Yang Yang <[email protected]>
>
> Psi_group's poll_min_period is determined by the min window size of
> psi_trigger when creating new triggers. While destroying a psi_trigger,
> there is no need to reset poll_min_period if the destroying psi_trigger
> not had the min windows size, since in this condition poll_min_period
> will keep the same as before.

Nice optimization.

>
> Signed-off-by: Yang Yang <[email protected]>

Acked-by: Suren Baghdasaryan <[email protected]>

> ---
> kernel/sched/psi.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
> index 02e011cabe91..12869585cf89 100644
> --- a/kernel/sched/psi.c
> +++ b/kernel/sched/psi.c
> @@ -1359,11 +1359,16 @@ void psi_trigger_destroy(struct psi_trigger *t)
> group->nr_triggers[t->state]--;
> if (!group->nr_triggers[t->state])
> group->poll_states &= ~(1 << t->state);
> - /* reset min update period for the remaining triggers */
> - list_for_each_entry(tmp, &group->triggers, node)
> - period = min(period, div_u64(tmp->win.size,
> - UPDATES_PER_WINDOW));
> - group->poll_min_period = period;
> + /*
> + * Reset min update period for the remaining triggers iff the destroying
> + * trigger had the min window size.
> + */
> + if (group->poll_min_period == div_u64(t->win.size, UPDATES_PER_WINDOW)) {
> + list_for_each_entry(tmp, &group->triggers, node)
> + period = min(period, div_u64(tmp->win.size,
> + UPDATES_PER_WINDOW));
> + group->poll_min_period = period;
> + }
> /* Destroy poll_task when the last trigger is destroyed */
> if (group->poll_states == 0) {
> group->polling_until = 0;
> --
> 2.25.1

2023-04-26 03:20:34

by Yang Yang

[permalink] [raw]
Subject: Re: [PATCH linux-next] sched/psi: avoid unnecessary resetting min update period when destroy trigger

>On Mon, Apr 17, 2023 at 1:12 AM <[email protected]> wrote:
>>
>> From: Yang Yang <[email protected]>
>>
>> Psi_group's poll_min_period is determined by the min window size of
>> psi_trigger when creating new triggers. While destroying a psi_trigger,
>> there is no need to reset poll_min_period if the destroying psi_trigger
>> not had the min windows size, since in this condition poll_min_period
>> will keep the same as before.
>
> Nice optimization.
>
>> Signed-off-by: Yang Yang <[email protected]>
> Acked-by: Suren Baghdasaryan <[email protected]>

Hi, would you please take a review?
Thanks!

2023-04-26 03:25:03

by Yang Yang

[permalink] [raw]
Subject: Re: [PATCH linux-next] sched/psi: avoid unnecessary resetting min update period when destroy trigger

>On Mon, Apr 17, 2023 at 1:12 AM <[email protected]> wrote:
>>
>> From: Yang Yang <[email protected]>
>>
>> Psi_group's poll_min_period is determined by the min window size of
>> psi_trigger when creating new triggers. While destroying a psi_trigger,
>> there is no need to reset poll_min_period if the destroying psi_trigger
>> not had the min windows size, since in this condition poll_min_period
>> will keep the same as before.
>
> Nice optimization.
>
>> Signed-off-by: Yang Yang <[email protected]>
> Acked-by: Suren Baghdasaryan <[email protected]>

Hi, would you please take a review?
Thanks!

2023-04-26 04:13:38

by Yang Yang

[permalink] [raw]
Subject: Re: [PATCH linux-next] sched/psi: avoid unnecessary resetting min update period when destroy trigger

> On Mon, Apr 17, 2023 at 1:12 AM <[email protected]> wrote:
>>
>> From: Yang Yang <[email protected]>
>>
>> Psi_group's poll_min_period is determined by the min window size of
>> psi_trigger when creating new triggers. While destroying a psi_trigger,
>> there is no need to reset poll_min_period if the destroying psi_trigger
>> not had the min windows size, since in this condition poll_min_period
>> will keep the same as before.
>
> Nice optimization.
>
>>
>> Signed-off-by: Yang Yang <[email protected]>
>
> Acked-by: Suren Baghdasaryan <[email protected]>

Hi, would you please take a review?
Thanks!

2023-04-26 05:10:38

by Suren Baghdasaryan

[permalink] [raw]
Subject: Re: [PATCH linux-next] sched/psi: avoid unnecessary resetting min update period when destroy trigger

On Tue, Apr 25, 2023 at 8:32 PM Yang Yang <[email protected]> wrote:
>
> > On Mon, Apr 17, 2023 at 1:12 AM <[email protected]> wrote:
> >>
> >> From: Yang Yang <[email protected]>
> >>
> >> Psi_group's poll_min_period is determined by the min window size of
> >> psi_trigger when creating new triggers. While destroying a psi_trigger,
> >> there is no need to reset poll_min_period if the destroying psi_trigger
> >> not had the min windows size, since in this condition poll_min_period
> >> will keep the same as before.
> >
> > Nice optimization.
> >
> >>
> >> Signed-off-by: Yang Yang <[email protected]>
> >
> > Acked-by: Suren Baghdasaryan <[email protected]>
>
> Hi, would you please take a review?

I guess this is a ping for PeterZ to queue this patch in his tree.
Peter, any issues with accepting this patch?

> Thanks!