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From: "tip-bot2 for Abel Wu" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Abel Wu <wuyun.abel@bytedance.com>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Mel Gorman <mgorman@suse.de>,
	x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: sched/core] sched/fair: Cleanup for SIS_PROP
Date: Fri, 09 Sep 2022 09:00:27 -0000	[thread overview]
Message-ID: <166271402714.401.13027499685283802470.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20220907112000.1854-6-wuyun.abel@bytedance.com>

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     96c1c0cfe493a7ed549169a6f044bbb83e490fb5
Gitweb:        https://git.kernel.org/tip/96c1c0cfe493a7ed549169a6f044bbb83e490fb5
Author:        Abel Wu <wuyun.abel@bytedance.com>
AuthorDate:    Wed, 07 Sep 2022 19:20:00 +08:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Wed, 07 Sep 2022 21:53:47 +02:00

sched/fair: Cleanup for SIS_PROP

The sched-domain of this cpu is only used for some heuristics when
SIS_PROP is enabled, and it should be irrelevant whether the local
sd_llc is valid or not, since all we care about is target sd_llc
if !SIS_PROP.

Access the local domain only when there is a need.

Signed-off-by: Abel Wu <wuyun.abel@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Link: https://lore.kernel.org/r/20220907112000.1854-6-wuyun.abel@bytedance.com
---
 kernel/sched/fair.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 23b020c..7bad641 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6396,19 +6396,19 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool 
 	struct sched_domain_shared *sd_share;
 	struct rq *this_rq = this_rq();
 	int this = smp_processor_id();
-	struct sched_domain *this_sd;
+	struct sched_domain *this_sd = NULL;
 	u64 time = 0;
 
-	this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
-	if (!this_sd)
-		return -1;
-
 	cpumask_and(cpus, sched_domain_span(sd), p->cpus_ptr);
 
 	if (sched_feat(SIS_PROP) && !has_idle_core) {
 		u64 avg_cost, avg_idle, span_avg;
 		unsigned long now = jiffies;
 
+		this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc));
+		if (!this_sd)
+			return -1;
+
 		/*
 		 * If we're busy, the assumption that the last idle period
 		 * predicts the future is flawed; age away the remaining
@@ -6462,7 +6462,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, bool 
 	if (has_idle_core)
 		set_idle_cores(target, false);
 
-	if (sched_feat(SIS_PROP) && !has_idle_core) {
+	if (sched_feat(SIS_PROP) && this_sd && !has_idle_core) {
 		time = cpu_clock(this) - time;
 
 		/*

      reply	other threads:[~2022-09-09  9:01 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-07 11:19 [PATCH v4 0/5] sched/fair: Minor SIS optimizations Abel Wu
2022-09-07 11:19 ` [PATCH v4 1/5] sched/fair: Remove redundant check in select_idle_smt() Abel Wu
2022-09-09  9:00   ` [tip: sched/core] " tip-bot2 for Abel Wu
2022-09-07 11:19 ` [PATCH v4 2/5] sched/fair: Avoid double search on same cpu Abel Wu
2022-09-09  9:00   ` [tip: sched/core] " tip-bot2 for Abel Wu
2022-09-07 11:19 ` [PATCH v4 3/5] sched/fair: Remove useless check in select_idle_core() Abel Wu
2022-09-09  9:00   ` [tip: sched/core] " tip-bot2 for Abel Wu
2022-09-07 11:19 ` [PATCH v4 4/5] sched/fair: Default to false in test_idle_cores() Abel Wu
2022-09-09  9:00   ` [tip: sched/core] " tip-bot2 for Abel Wu
2022-09-07 11:20 ` [PATCH v4 5/5] sched/fair: Cleanup for SIS_PROP Abel Wu
2022-09-09  9:00   ` tip-bot2 for Abel Wu [this message]

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