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From:   Abel Wu <wuyun.abel@bytedance.com>
To:     Ingo Molnar <mingo@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        Daniel Bristot de Oliveira <bristot@redhat.com>
Cc:     linux-kernel@vger.kernel.org
Subject: [RFC PATCH 4/5] sched/fair: filter out overloaded cpus in sis
Date:   Thu, 17 Feb 2022 23:44:00 +0800
Message-Id: <20220217154403.6497-5-wuyun.abel@bytedance.com>
In-Reply-To: <20220217154403.6497-1-wuyun.abel@bytedance.com>
References: <20220217154403.6497-1-wuyun.abel@bytedance.com>
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Skip overloaded cpus in SIS if any. This improves idle
cpu searching, especially under the SIS_PROP constrain
that search depth is limited.

The mask of overloaded cpus might not be quite accurate
since it is generally updated at tick granule, but the
overloaded cpus are unlikely to go into idle shortly.

Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
---
 kernel/sched/fair.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c83c0864e429..1d8f396e6f41 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6273,6 +6273,9 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool
 
 	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
 
+	if (atomic_read(&sd->shared->nr_overloaded))
+		cpumask_andnot(cpus, cpus, sdo_mask(sd->shared));
+
 	if (sched_feat(SIS_PROP) && !has_idle_core) {
 		u64 avg_cost, avg_idle, span_avg;
 		unsigned long now = jiffies;
-- 
2.11.0