linux-kernel - [PATCH 5/6] cgroup/cpuset: optimize cpuset_mems_allowed

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Date: Mon, 13 May 2024 15:01:45 -0700
From: Yury Norov <yury.norov@...il.com>
To: linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Ben Segall <bsegall@...gle.com>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Frederic Weisbecker <frederic@...nel.org>,
	Imran Khan <imran.f.khan@...cle.com>,
	Ingo Molnar <mingo@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Leonardo Bras <leobras@...hat.com>,
	Mel Gorman <mgorman@...e.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Rik van Riel <riel@...riel.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Tejun Heo <tj@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Waiman Long <longman@...hat.com>,
	Yury Norov <yury.norov@...il.com>,
	Zefan Li <lizefan.x@...edance.com>,
	cgroups@...r.kernel.org
Subject: [PATCH 5/6] cgroup/cpuset: optimize cpuset_mems_allowed_intersects()

If the function is called with tsk1 == tsk2, we know for sure that their
mems_allowed nodes do intersect, and so we can return immediately instead
of checking the nodes content.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 kernel/cgroup/cpuset.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 4237c8748715..47ed206d4890 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -5010,6 +5010,9 @@ EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
 int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
 				   const struct task_struct *tsk2)
 {
+	if (tsk1 == tsk2)
+		return 1;
+
 	return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
 }
 
-- 
2.40.1