sched/psi: Avoid updating PSI triggers and ->rtpoll_total when there are no state...

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

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index be853f227e40d433b6e46f718d50214ea489d652..79f8db0c6150dff94480dd748d26425988ef3524 100644 (file)
--- 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,