[RFC 05/11] sched/fair: Re-arrange select_idle_cpu()

From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org, linux-kernel@vger.kernel.org
Cc: subhra.mazumdar@oracle.com, steven.sistare@oracle.com,
	dhaval.giani@oracle.com, rohit.k.jain@oracle.com,
	umgwanakikbuti@gmail.com, matt@codeblueprint.co.uk,
	riel@surriel.com, peterz@infradead.org
Subject: [RFC 05/11] sched/fair: Re-arrange select_idle_cpu()
Date: Wed, 30 May 2018 16:22:41 +0200	[thread overview]
Message-ID: <20180530143106.133840135@infradead.org> (raw)
In-Reply-To: 20180530142236.667774973@infradead.org

[-- Attachment #1: peterz-sis-again-5.patch --]
[-- Type: text/plain, Size: 1448 bytes --]

In preparation of the next patch, move the actual scanning of the LLC
out of the whole proportional/cost metric stuff, so we can change it
out in a next patch.

Should not actually change anything.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/fair.c |   28 ++++++++++++++++++----------
 1 file changed, 18 insertions(+), 10 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6364,6 +6364,23 @@ static inline int select_idle_smt(struct
 
 #endif /* CONFIG_SCHED_SMT */
 
+static int __select_idle_cpu(struct task_struct *p, struct sched_domain *sd,
+			     int target, int nr, int *ploops)
+{
+	int cpu;
+
+	for_each_cpu_wrap(cpu, sched_domain_span(sd), target) {
+		if ((*ploops)++ >= nr)
+			return -1;
+		if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
+			continue;
+		if (available_idle_cpu(cpu))
+			break;
+	}
+
+	return cpu;
+}
+
 /*
  * Scan the LLC domain for idle CPUs; this is dynamically regulated by
  * comparing the average scan cost (tracked in sd->avg_scan_cost) against the
@@ -6420,16 +6437,7 @@ static int select_idle_cpu(struct task_s
 
 	time = local_clock();
 
-	for_each_cpu_wrap(cpu, sched_domain_span(sd), target) {
-		if (loops++ >= nr) {
-			cpu = -1;
-			break;
-		}
-		if (!cpumask_test_cpu(cpu, &p->cpus_allowed))
-			continue;
-		if (available_idle_cpu(cpu))
-			break;
-	}
+	cpu = __select_idle_cpu(p, sd, target, nr, &loops);
 
 	time = local_clock() - time;
 
