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From: subhra mazumdar <subhra.mazumdar@oracle.com>
To: linux-kernel@vger.kernel.org
Cc: peterz@infradead.org, mingo@redhat.com,
	steven.sistare@oracle.com, dhaval.giani@oracle.com,
	rohit.k.jain@oracle.com, daniel.lezcano@linaro.org
Subject: [PATCH 5/5] sched: SIS_CORE to disable idle core search
Date: Tue, 12 Jun 2018 10:50:02 -0700	[thread overview]
Message-ID: <20180612175002.31453-6-subhra.mazumdar@oracle.com> (raw)
In-Reply-To: <20180612175002.31453-1-subhra.mazumdar@oracle.com>

Use SIS_CORE to disable idle core search. For some workloads
select_idle_core becomes a scalability bottleneck, removing it improves
throughput. Also there are workloads where disabling it can hurt latency,
so need to have an option.

Signed-off-by: subhra mazumdar <subhra.mazumdar@oracle.com>
---
 kernel/sched/fair.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 849c7c8..35a076e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6464,9 +6464,11 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 	if (!sd)
 		return target;
 
-	i = select_idle_core(p, sd, target);
-	if ((unsigned)i < nr_cpumask_bits)
-		return i;
+	if (sched_feat(SIS_CORE)) {
+		i = select_idle_core(p, sd, target);
+		if ((unsigned)i < nr_cpumask_bits)
+			return i;
+	}
 
 	i = select_idle_cpu(p, sd, target);
 	if ((unsigned)i < nr_cpumask_bits)
-- 
2.9.3


  parent reply	other threads:[~2018-06-12 17:48 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-12 17:49 [RFC/RFT V2 PATCH 0/5] Improve scheduler scalability for fast path subhra mazumdar
2018-06-12 17:49 ` [PATCH 1/5] sched: limit cpu search in select_idle_cpu subhra mazumdar
2018-06-12 20:33   ` kbuild test robot
2018-06-12 22:12     ` Subhra Mazumdar
2018-06-20  7:32   ` [lkp-robot] [sched] 8dd662615c: reaim.jobs_per_min -3.3% regression kernel test robot
2018-06-12 17:49 ` [PATCH 2/5] sched: introduce per-cpu var next_cpu to track search limit subhra mazumdar
2018-06-12 17:50 ` [PATCH 3/5] sched: rotate the cpu search window for better spread subhra mazumdar
2018-06-12 17:50 ` [PATCH 4/5] sched: add sched feature to disable idle core search subhra mazumdar
2018-06-12 17:50 ` subhra mazumdar [this message]
2018-06-28 22:44 [RESEND RFC/RFT V2 PATCH 0/5] Improve scheduler scalability for fast path subhra mazumdar
2018-06-28 22:44 ` [PATCH 5/5] sched: SIS_CORE to disable idle core search subhra mazumdar

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