linux-kernel - [tip: sched/core] psi: Fix trigger being fired unexpectedly at initial

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Date:   Fri, 22 Apr 2022 10:27:46 -0000
From:   "tip-bot2 for Hailong Liu" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Hailong Liu <liuhailong@...ux.alibaba.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Suren Baghdasaryan <surenb@...gle.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] psi: Fix trigger being fired unexpectedly at initial

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     915a087e4c47334a2f7ba2a4092c4bade0873769
Gitweb:        https://git.kernel.org/tip/915a087e4c47334a2f7ba2a4092c4bade0873769
Author:        Hailong Liu <liuhailong@...ux.alibaba.com>
AuthorDate:    Fri, 01 Apr 2022 13:10:11 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 22 Apr 2022 12:14:06 +02:00

psi: Fix trigger being fired unexpectedly at initial

When a trigger being created, its win.start_value and win.start_time are
reset to zero. If group->total[PSI_POLL][t->state] has accumulated before,
this trigger will be fired unexpectedly in the next period, even if its
growth time does not reach its threshold.

So set the window of the new trigger to the current state value.

Signed-off-by: Hailong Liu <liuhailong@...ux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Acked-by: Suren Baghdasaryan <surenb@...gle.com>
Link: https://lore.kernel.org/r/1648789811-3788971-1-git-send-email-liuhailong@linux.alibaba.com
---
 kernel/sched/psi.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index a4fa3aa..5a49a8c 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -1117,7 +1117,8 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
 	t->state = state;
 	t->threshold = threshold_us * NSEC_PER_USEC;
 	t->win.size = window_us * NSEC_PER_USEC;
-	window_reset(&t->win, 0, 0, 0);
+	window_reset(&t->win, sched_clock(),
+			group->total[PSI_POLL][t->state], 0);
 
 	t->event = 0;
 	t->last_event_time = 0;