linux-kernel - [PATCH 4/4] sched/isolation: don't alloc twice for housekeeping.cpumasks

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Message-ID: <20250410092423.9831-4-alexs@kernel.org>
Date: Thu, 10 Apr 2025 17:24:19 +0800
From: alexs@...nel.org
To: 
Cc: linux-kernel@...r.kernel.org,
	Alex Shi <alexs@...nel.org>,
	Valentin Schneider <vschneid@...hat.com>,
	Ben Segall <bsegall@...gle.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
Subject: [PATCH 4/4] sched/isolation: don't alloc twice for housekeeping.cpumasks

From: Alex Shi <alexs@...nel.org>

The variable housekeeping.cpumasks[type] will be alloced twice if
nohz_full and isolcpus are both setup in cmdline, that shouldn't to do
so. Just alloc once is enough and save a bit memory.

Signed-off-by: Alex Shi <alexs@...nel.org>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
---
 kernel/sched/isolation.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index e93776740725..44ab46b31f6b 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -103,10 +103,10 @@ void __init housekeeping_init(void)
 static void __init housekeeping_setup_type(enum hk_type type,
 					   cpumask_var_t housekeeping_staging)
 {
+	if (cpumask_empty(housekeeping.cpumasks[type]))
+		alloc_bootmem_cpumask_var(&housekeeping.cpumasks[type]);
 
-	alloc_bootmem_cpumask_var(&housekeeping.cpumasks[type]);
-	cpumask_copy(housekeeping.cpumasks[type],
-		     housekeeping_staging);
+	cpumask_copy(housekeeping.cpumasks[type], housekeeping_staging);
 }
 
 static int __init housekeeping_setup(char *str, unsigned long flags)
-- 
2.47.1