linux-kernel - [PATCH 2/2] sched/topology: optimize topology_span

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Message-ID: <20240802175750.1152788-3-yury.norov@gmail.com>
Date: Fri,  2 Aug 2024 10:57:43 -0700
From: Yury Norov <yury.norov@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Yury Norov <yury.norov@...il.com>,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	Leonardo Bras <leobras@...hat.com>,
	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>
Subject: [PATCH 2/2] sched/topology: optimize topology_span_sane()

The function may call cpumask_equal with tl->mask(cpu) == tl->mask(i),
even when cpu != i. In such case, cpumask_equal() would always return
true, and we can proceed to the next iteration immediately.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 kernel/sched/topology.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 754ad5fa3c99..571759606954 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -2368,6 +2368,8 @@ static bool topology_span_sane(struct sched_domain_topology_level *tl,
 	 */
 	for_each_cpu_from(i, cpu_map) {
 		mi = tl->mask(i);
+		if (mi == mc)
+			continue;
 
 		/*
 		 * We should 'and' all those masks with 'cpu_map' to exactly
-- 
2.43.0