[PATCH v5 3/4] sched/psi: extract update_triggers side effect

From: Domenico Cerasuolo
Date: Thu Mar 30 2023 - 04:11:23 EST


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@xxxxxxxxxxx>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@xxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
kernel/sched/psi.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index a3d0b5cf797a..f3df6a8ff493 100644
--- 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,
--
2.34.1