From e7e24442a1ef3a4d4049bbeb8b3b183e9bc45e77 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Fri, 14 Apr 2017 17:32:07 +0200
Subject: [PATCH] sched/topology: Simplify build_overlap_sched_groups()

References: bnc#978907 Scheduler performance -- topology
Patch-mainline: v4.13-rc1
Git-commit: 91eaed0d61319f58a9f8e43d41a8cbb069b4f73d

Now that the first group will always be the previous domain of this
@cpu this can be simplified.

In fact, writing the code now removed should've been a big clue I was
doing it wrong :/

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/topology.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 10096278ec1c..6cd482e88abb 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -573,7 +573,7 @@ static void init_overlap_sched_group(struct sched_domain *sd,
 static int
 build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 {
-	struct sched_group *first = NULL, *last = NULL, *groups = NULL, *sg;
+	struct sched_group *first = NULL, *last = NULL, *sg;
 	const struct cpumask *span = sched_domain_span(sd);
 	struct cpumask *covered = sched_domains_tmpmask;
 	struct sd_data *sdd = sd->private;
@@ -603,15 +603,6 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 
 		init_overlap_sched_group(sd, sg, i);
 
-		/*
-		 * Make sure the first group of this domain contains the
-		 * canonical balance CPU. Otherwise the sched_domain iteration
-		 * breaks. See update_sg_lb_stats().
-		 */
-		if ((!groups && cpumask_test_cpu(cpu, sg_span)) ||
-		    group_balance_cpu(sg) == cpu)
-			groups = sg;
-
 		if (!first)
 			first = sg;
 		if (last)
@@ -619,7 +610,7 @@ build_overlap_sched_groups(struct sched_domain *sd, int cpu)
 		last = sg;
 		last->next = first;
 	}
-	sd->groups = groups;
+	sd->groups = first;
 
 	return 0;