sched/psi: Extract update_triggers side effect

This change moves update_total flag out of update_triggers function,
currently called only in psi_poll_work.
In the next patch, update_triggers will be called also in psi_avgs_work,
but the total update information is specific to psi_poll_work.
Returning update_total value to the caller let us avoid differentiating
the implementation of update_triggers for different aggregators.

Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Link: https://lore.kernel.org/r/20230330105418.77061-4-cerasuolodomenico@gmail.com

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index a3d0b5cf797ab3b2f220b4d5d457933a4fa77dd9..f3df6a8ff493caefba60da136be7ffe38bf07f8f 100644 (file)
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -430,11 +430,11 @@ static u64 window_update(struct psi_window *win, u64 now, u64 value)
        return growth;
 }
 
-static u64 update_triggers(struct psi_group *group, u64 now)
+static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total)
 {
        struct psi_trigger *t;
-       bool update_total = false;
        u64 *total = group->total[PSI_POLL];
+       *update_total = false;
 
        /*
         * On subsequent updates, calculate growth deltas and let
@@ -462,7 +462,7 @@ static u64 update_triggers(struct psi_group *group, u64 now)
                         * been through all of them. Also remember to extend the
                         * polling time if we see new stall activity.
                         */
-                       update_total = true;
+                       *update_total = true;
 
                        /* Calculate growth since last update */
                        growth = window_update(&t->win, now, total[t->state]);
@@ -485,10 +485,6 @@ static u64 update_triggers(struct psi_group *group, u64 now)
                t->pending_event = false;
        }
 
-       if (update_total)
-               memcpy(group->rtpoll_total, total,
-                               sizeof(group->rtpoll_total));
-
        return now + group->rtpoll_min_period;
 }
 
@@ -622,6 +618,7 @@ static void psi_rtpoll_work(struct psi_group *group)
 {
        bool force_reschedule = false;
        u32 changed_states;
+       bool update_total;
        u64 now;
 
        mutex_lock(&group->rtpoll_trigger_lock);
@@ -686,8 +683,12 @@ static void psi_rtpoll_work(struct psi_group *group)
                goto out;
        }
 
-       if (now >= group->rtpoll_next_update)
-               group->rtpoll_next_update = update_triggers(group, now);
+       if (now >= group->rtpoll_next_update) {
+               group->rtpoll_next_update = update_triggers(group, now, &update_total);
+               if (update_total)
+                       memcpy(group->rtpoll_total, group->total[PSI_POLL],
+                                  sizeof(group->rtpoll_total));
+       }
 
        psi_schedule_rtpoll_work(group,
                nsecs_to_jiffies(group->rtpoll_next_update - now) + 1,