From 181d7e8b54820c4844eac12be010d6411540021d Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Mon, 1 May 2017 08:51:05 +0200
Subject: [PATCH] sched/topology: Simplify sched_group_mask() usage

References: bnc#978907 Scheduler performance -- topology
Patch-mainline: v4.13-rc1
Git-commit: af218122b103900fa33d408aea0c2468791e698c

While writing the comments, it occurred to me that:

  sg_cpus & sg_mask == sg_mask

at least conceptually; the !overlap case sets the all 1s mask. If we
correct that we can simplify things and directly use sg_mask.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/sched/fair.c     | 7 +++----
 kernel/sched/topology.c | 5 +++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bafa4e04b850..713a3106693e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7915,7 +7915,7 @@ static int active_load_balance_cpu_stop(void *data);
 static int should_we_balance(struct lb_env *env)
 {
 	struct sched_group *sg = env->sd->groups;
-	struct cpumask *sg_cpus, *sg_mask;
+	struct cpumask *sg_mask;
 	int cpu, balance_cpu = -1;
 
 	/*
@@ -7925,11 +7925,10 @@ static int should_we_balance(struct lb_env *env)
 	if (env->idle == CPU_NEWLY_IDLE)
 		return 1;
 
-	sg_cpus = sched_group_cpus(sg);
 	sg_mask = sched_group_mask(sg);
 	/* Try to find first idle cpu */
-	for_each_cpu_and(cpu, sg_cpus, env->cpus) {
-		if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu))
+	for_each_cpu_and(cpu, sg_mask, env->cpus) {
+		if (!idle_cpu(cpu))
 			continue;
 
 		balance_cpu = cpu;
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index dea1950b42a5..bf53a99eb511 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -85,7 +85,8 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
 				group->sgc->id,
 				cpumask_pr_args(sched_group_cpus(group)));
 
-		if ((sd->flags & SD_OVERLAP) && !cpumask_full(sched_group_mask(group))) {
+		if ((sd->flags & SD_OVERLAP) &&
+		    !cpumask_equal(sched_group_mask(group), sched_group_cpus(group))) {
 			printk(KERN_CONT " mask=%*pbl",
 				cpumask_pr_args(sched_group_mask(group)));
 		}
@@ -505,7 +506,7 @@ enum s_alloc {
  */
 int group_balance_cpu(struct sched_group *sg)
 {
-	return cpumask_first_and(sched_group_cpus(sg), sched_group_mask(sg));
+	return cpumask_first(sched_group_mask(sg));
 }