linux-kernel - [tip: sched/core] sched,stats: Further simplify sched

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Date:   Wed, 19 May 2021 08:09:07 -0000
From:   "tip-bot2 for Peter Zijlstra" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Mel Gorman <mgorman@...e.de>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched,stats: Further simplify sched_info

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

Commit-ID:     90a0ff4ec9c65cae3085d23301933172cea3f38a
Gitweb:        https://git.kernel.org/tip/90a0ff4ec9c65cae3085d23301933172cea3f38a
Author:        Peter Zijlstra <peterz@...radead.org>
AuthorDate:    Wed, 12 May 2021 13:32:37 +02:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Tue, 18 May 2021 12:53:53 +02:00

sched,stats: Further simplify sched_info

There's no point doing delta==0 updates.

Suggested-by: Mel Gorman <mgorman@...e.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/stats.h | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h
index 33ffd41..111072e 100644
--- a/kernel/sched/stats.h
+++ b/kernel/sched/stats.h
@@ -160,10 +160,11 @@ static inline void sched_info_dequeue(struct rq *rq, struct task_struct *t)
 {
 	unsigned long long delta = 0;
 
-	if (t->sched_info.last_queued) {
-		delta = rq_clock(rq) - t->sched_info.last_queued;
-		t->sched_info.last_queued = 0;
-	}
+	if (!t->sched_info.last_queued)
+		return;
+
+	delta = rq_clock(rq) - t->sched_info.last_queued;
+	t->sched_info.last_queued = 0;
 	t->sched_info.run_delay += delta;
 
 	rq_sched_info_dequeue(rq, delta);
@@ -176,12 +177,14 @@ static inline void sched_info_dequeue(struct rq *rq, struct task_struct *t)
  */
 static void sched_info_arrive(struct rq *rq, struct task_struct *t)
 {
-	unsigned long long now = rq_clock(rq), delta = 0;
+	unsigned long long now, delta = 0;
 
-	if (t->sched_info.last_queued) {
-		delta = now - t->sched_info.last_queued;
-		t->sched_info.last_queued = 0;
-	}
+	if (!t->sched_info.last_queued)
+		return;
+
+	now = rq_clock(rq);
+	delta = now - t->sched_info.last_queued;
+	t->sched_info.last_queued = 0;
 	t->sched_info.run_delay += delta;
 	t->sched_info.last_arrival = now;
 	t->sched_info.pcount++;