Messages in this thread Patch in this message | | | Date | Wed, 11 Oct 2023 23:15:16 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH linux-next v3 2/4] sched/psi: Avoid update triggers and rtpoll_total when it is unnecessary |
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* yang.yang29@zte.com.cn <yang.yang29@zte.com.cn> wrote:
> From: Yang Yang <yang.yang29@zte.com.cn> > > When psimon wakes up and there are no state changes for rtpoll_states, > it's unnecessary to update triggers and rtpoll_total because the pressures > being monitored by user had not changed. > This will help to slightly reduce unnecessary computations of psi. > > Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> > Cc: Zhang Yunkai <zhang.yunkai@zte.com.cn> > Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn> > --- > kernel/sched/psi.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c > index be853f227e40..143f8eb34f9d 100644 > --- a/kernel/sched/psi.c > +++ b/kernel/sched/psi.c > @@ -704,11 +704,12 @@ static void psi_rtpoll_work(struct psi_group *group) > } > > if (now >= group->rtpoll_next_update) { > - update_triggers(group, now, &update_total, PSI_POLL); > group->rtpoll_next_update = now + group->rtpoll_min_period; > - if (update_total) > + if (changed_states & group->rtpoll_states) { > + update_triggers(group, now, &update_total, PSI_POLL); > memcpy(group->rtpoll_total, group->total[PSI_POLL], > sizeof(group->rtpoll_total)); > + }
Yeah, so I believe we may have been talking past each other for past versions of this patch: why is this patch modifying the order of the modification to group->rtpoll_next_update?
It should do the below sequence, nothing more - see the patch attached below. This is basically a combination of patches #2 and #3.
And then the final patch removes the now superfluous 'update_total' parameter, which is always true.
Here are the commits I applied to tip:sched/core:
e03dc9fa0663 sched/psi: Change update_triggers() to a 'void' function ... 80cc1d1d5ee3 sched/psi: Avoid updating PSI triggers and ->rtpoll_total when there are no state changes 3657680f38cd sched/psi: Delete the 'update_total' function parameter from update_triggers()
I rewrote the changelogs for readability.
Thanks,
Ingo
===================> From: Yang Yang <yang.yang29@zte.com.cn> Date: Tue, 10 Oct 2023 16:41:07 +0800 Subject: [PATCH] sched/psi: Avoid updating PSI triggers and ->rtpoll_total when there are no state changes
When psimon wakes up and there are no state changes for ->rtpoll_states, it's unnecessary to update triggers and ->rtpoll_total because the pressures being monitored by the user have not changed.
This will help to slightly reduce unnecessary computations of PSI.
[ mingo: Changelog updates ]
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Peter Ziljstra <peterz@infradead.org> Link: https://lore.kernel.org/r/202310101641075436843@zte.com.cn --- kernel/sched/psi.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index be853f227e40..79f8db0c6150 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -704,11 +704,12 @@ static void psi_rtpoll_work(struct psi_group *group) } if (now >= group->rtpoll_next_update) { - update_triggers(group, now, &update_total, PSI_POLL); - group->rtpoll_next_update = now + group->rtpoll_min_period; - if (update_total) + if (changed_states & group->rtpoll_states) { + update_triggers(group, now, &update_total, PSI_POLL); memcpy(group->rtpoll_total, group->total[PSI_POLL], sizeof(group->rtpoll_total)); + } + group->rtpoll_next_update = now + group->rtpoll_min_period; } psi_schedule_rtpoll_work(group,
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