[1/1] sched/psi: avoid resetting the min update period when it is unnecessary
Commit Message
From: Yang Yang <yang.yang29@zte.com.cn>
Psi_group's poll_min_period is determined by the minimum 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 psi_trigger being
destroyed did not have the minimum window size, since in this condition
poll_min_period will remain the same as before.
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Acked-by: Suren Baghdasaryan <surenb@google.com>
---
rebase of https://lore.kernel.org/all/202305121642367753446@zte.com.cn/
over git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core branch
kernel/sched/psi.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
Comments
On Sun, May 14, 2023 at 09:33:38AM -0700, Suren Baghdasaryan wrote:
> From: Yang Yang <yang.yang29@zte.com.cn>
>
> Psi_group's poll_min_period is determined by the minimum 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 psi_trigger being
> destroyed did not have the minimum window size, since in this condition
> poll_min_period will remain the same as before.
>
> Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
> Acked-by: Suren Baghdasaryan <surenb@google.com>
> ---
> rebase of https://lore.kernel.org/all/202305121642367753446@zte.com.cn/
> over git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/core branch
Thanks!
@@ -1407,11 +1407,16 @@ void psi_trigger_destroy(struct psi_trigger *t)
group->rtpoll_nr_triggers[t->state]--;
if (!group->rtpoll_nr_triggers[t->state])
group->rtpoll_states &= ~(1 << t->state);
- /* reset min update period for the remaining triggers */
- list_for_each_entry(tmp, &group->rtpoll_triggers, node)
- period = min(period, div_u64(tmp->win.size,
- UPDATES_PER_WINDOW));
- group->rtpoll_min_period = period;
+ /*
+ * Reset min update period for the remaining triggers
+ * iff the destroying trigger had the min window size.
+ */
+ if (group->rtpoll_min_period == div_u64(t->win.size, UPDATES_PER_WINDOW)) {
+ list_for_each_entry(tmp, &group->rtpoll_triggers, node)
+ period = min(period, div_u64(tmp->win.size,
+ UPDATES_PER_WINDOW));
+ group->rtpoll_min_period = period;
+ }
/* Destroy rtpoll_task when the last trigger is destroyed */
if (group->rtpoll_states == 0) {
group->rtpoll_until = 0;