linux-kernel - [tip: sched/core] sched/fair: Take the scheduling domain into account in select_idle

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Date: Wed, 28 Feb 2024 22:00:10 -0000
From: "tip-bot2 for Keisuke Nishimura" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Keisuke Nishimura <keisuke.nishimura@...ia.fr>,
 Julia Lawall <julia.lawall@...ia.fr>, Ingo Molnar <mingo@...nel.org>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Take the scheduling domain into account
 in select_idle_core()

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

Commit-ID:     23d04d8c6b8ec339057264659b7834027f3e6a63
Gitweb:        https://git.kernel.org/tip/23d04d8c6b8ec339057264659b7834027f3e6a63
Author:        Keisuke Nishimura <keisuke.nishimura@...ia.fr>
AuthorDate:    Wed, 10 Jan 2024 14:17:07 +01:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 28 Feb 2024 15:15:49 +01:00

sched/fair: Take the scheduling domain into account in select_idle_core()

When picking a CPU on task wakeup, select_idle_core() has to take
into account the scheduling domain where the function looks for the CPU.

This is because the "isolcpus" kernel command line option can remove CPUs
from the domain to isolate them from other SMT siblings.

This change replaces the set of CPUs allowed to run the task from
p->cpus_ptr by the intersection of p->cpus_ptr and sched_domain_span(sd)
which is stored in the 'cpus' argument provided by select_idle_cpu().

Fixes: 9fe1f127b913 ("sched/fair: Merge select_idle_core/cpu()")
Signed-off-by: Keisuke Nishimura <keisuke.nishimura@...ia.fr>
Signed-off-by: Julia Lawall <julia.lawall@...ia.fr>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20240110131707.437301-2-keisuke.nishimura@inria.fr
---
 kernel/sched/fair.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 005f6d3..352222d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7289,7 +7289,7 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu
 		if (!available_idle_cpu(cpu)) {
 			idle = false;
 			if (*idle_cpu == -1) {
-				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, p->cpus_ptr)) {
+				if (sched_idle_cpu(cpu) && cpumask_test_cpu(cpu, cpus)) {
 					*idle_cpu = cpu;
 					break;
 				}
@@ -7297,7 +7297,7 @@ static int select_idle_core(struct task_struct *p, int core, struct cpumask *cpu
 			}
 			break;
 		}
-		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, p->cpus_ptr))
+		if (*idle_cpu == -1 && cpumask_test_cpu(cpu, cpus))
 			*idle_cpu = cpu;
 	}