From: Christoph Lameter <clameter@sgi.com>
Date: Sun, 10 Dec 2006 10:20:13 +0000 (-0800)
Subject: [PATCH] sched: avoid taking rq lock in wake_priority_sleeper
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=571f6d2fb0b1c04798df783db2ba85e96bcce43d;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

[PATCH] sched: avoid taking rq lock in wake_priority_sleeper

Avoid taking the request queue lock in wake_priority_sleeper if there are no
running processes.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index f04add905bdf..fdd26fffaa20 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2915,6 +2915,9 @@ static inline int wake_priority_sleeper(struct rq *rq)
 	int ret = 0;
 
 #ifdef CONFIG_SCHED_SMT
+	if (!rq->nr_running)
+		return 0;
+
 	spin_lock(&rq->lock);
 	/*
 	 * If an SMT sibling task has been put to sleep for priority