linux-kernel - [tip: sched/core] sched/fair: Drop useless cpumask_empty() in find_energy_efficient

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <176820500847.510.12871490155322269241.tip-bot2@tip-bot2>
Date: Mon, 12 Jan 2026 08:03:28 -0000
From: "tip-bot2 for Yury Norov (NVIDIA)" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Yury Norov (NVIDIA)" <yury.norov@...il.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Madadi Vineeth Reddy <vineethr@...ux.ibm.com>,
 K Prateek Nayak <kprateek.nayak@....com>,
 Vincent Guittot <vincent.guittot@...aro.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: sched/core] sched/fair: Drop useless cpumask_empty() in
 find_energy_efficient_cpu()

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

Commit-ID:     ff1de90dd7a69ef43586683535ad87ab899a1214
Gitweb:        https://git.kernel.org/tip/ff1de90dd7a69ef43586683535ad87ab899a1214
Author:        Yury Norov (NVIDIA) <yury.norov@...il.com>
AuthorDate:    Sat, 06 Dec 2025 23:05:42 -05:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Thu, 08 Jan 2026 12:43:56 +01:00

sched/fair: Drop useless cpumask_empty() in find_energy_efficient_cpu()

cpumask_empty() call is O(N) and useless because the previous
cpumask_and() returns false for empty 'cpus'. Drop it.

Signed-off-by: Yury Norov (NVIDIA) <yury.norov@...il.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Madadi Vineeth Reddy <vineethr@...ux.ibm.com>
Reviewed-by: K Prateek Nayak <kprateek.nayak@....com>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Link: https://patch.msgid.link/20251207040543.407695-1-yury.norov@gmail.com
---
 kernel/sched/fair.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 7377f91..64275d7 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8359,9 +8359,7 @@ static int find_energy_efficient_cpu(struct task_struct *p, int prev_cpu)
 		int max_spare_cap_cpu = -1;
 		int fits, max_fits = -1;
 
-		cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask);
-
-		if (cpumask_empty(cpus))
+		if (!cpumask_and(cpus, perf_domain_span(pd), cpu_online_mask))
 			continue;
 
 		/* Account external pressure for the energy estimation */