linux-kernel - [PATCH v2 2/3] sched/fair: Use rq in idle_cpu

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Date: Mon, 15 Jan 2024 15:34:25 +0100
From: Pierre Gondois <pierre.gondois@....com>
To: linux-kernel@...r.kernel.org
Cc: Shrikanth Hegde <sshegde@...ux.vnet.ibm.com>,
	Pierre Gondois <pierre.gondois@....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>,
	Daniel Bristot de Oliveira <bristot@...hat.com>,
	Valentin Schneider <vschneid@...hat.com>,
	Huang Ying <ying.huang@...el.com>
Subject: [PATCH v2 2/3] sched/fair: Use rq in idle_cpu_without()

idle_cpu_without() could receive a 'struct rq' instead of a
CPU number to avoid converting the CPU number to a 'struct rq'
two times. Indeed update_sg_wakeup_stats() already makes the
conversion.
idle_cpu_without() is also renamed to idle_rq_without()
to match the input parameter.

Reviewed-by: Shrikanth Hegde <sshegde@...ux.vnet.ibm.com>
Signed-off-by: Pierre Gondois <pierre.gondois@....com>
---
 kernel/sched/fair.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d7a3c63a2171..97d9e0d32337 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -10105,23 +10105,21 @@ static unsigned int task_running_on_cpu(int cpu, struct task_struct *p)
 }
 
 /**
- * idle_cpu_without - would a given CPU be idle without p ?
- * @cpu: the processor on which idleness is tested.
+ * idle_rq_without - would a given rq be idle without p ?
+ * @rq: the rq on which idleness is tested.
  * @p: task which should be ignored.
  *
- * Return: 1 if the CPU would be idle. 0 otherwise.
+ * Return: 1 if the rq would be idle. 0 otherwise.
  */
-static int idle_cpu_without(int cpu, struct task_struct *p)
+static int idle_rq_without(struct rq *rq, struct task_struct *p)
 {
-	struct rq *rq = cpu_rq(cpu);
-
 	if (rq->curr != rq->idle && rq->curr != p)
 		return 0;
 
 	/*
 	 * rq->nr_running can't be used but an updated version without the
 	 * impact of p on cpu must be used instead. The updated nr_running
-	 * be computed and tested before calling idle_cpu_without().
+	 * be computed and tested before calling idle_rq_without().
 	 */
 
 #ifdef CONFIG_SMP
@@ -10166,9 +10164,9 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd,
 		sgs->sum_nr_running += nr_running;
 
 		/*
-		 * No need to call idle_cpu_without() if nr_running is not 0
+		 * No need to call idle_rq_without() if nr_running is not 0
 		 */
-		if (!nr_running && idle_cpu_without(i, p))
+		if (!nr_running && idle_rq_without(rq, p))
 			sgs->idle_cpus++;
 
 		/* Check if task fits in the CPU */
-- 
2.25.1