From 33b4484f1bb13cb16808f3242b0183b622c4d4c1 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
Date: Wed, 4 Aug 2021 12:58:57 +0100
Subject: [PATCH] sched/fair: Avoid a second scan of target in select_idle_cpu

Patch-mainline: v5.15-rc1
References: bsc#1189999 (Scheduler functional and performance backports)
Git-commit: 56498cfb045d7147cdcba33795d19429afcd1d00

When select_idle_cpu starts scanning for an idle CPU, it starts with
a target CPU that has already been checked by select_idle_sibling.
This patch starts with the next CPU instead.

Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210804115857.6253-3-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index b826743871bb..33ddd82274ca 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6249,7 +6249,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool
 		time = cpu_clock(this);
 	}
 
-	for_each_cpu_wrap(cpu, cpus, target) {
+	for_each_cpu_wrap(cpu, cpus, target + 1) {
 		if (has_idle_core) {
 			i = select_idle_core(p, cpu, cpus, &idle_cpu);
 			if ((unsigned int)i < nr_cpumask_bits)