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Sat, 06 Dec 2025 20:05:44 -0800 (PST) Received: from localhost ([2601:346:0:79bd:7387:2d57:6cc5:314a]) by smtp.gmail.com with ESMTPSA id 00721157ae682-78c1b4ae73asm34386777b3.5.2025.12.06.20.05.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 06 Dec 2025 20:05:44 -0800 (PST) From: "Yury Norov (NVIDIA)" To: Peter Zijlstra , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , linux-kernel@vger.kernel.org Cc: "Yury Norov (NVIDIA)" , Markus Elfring , Madadi Vineeth Reddy , K Prateek Nayak Subject: [PATCH RESEND] sched: fair: drop useless cpumask_empty() in find_energy_efficient_cpu() Date: Sat, 6 Dec 2025 23:05:42 -0500 Message-ID: <20251207040543.407695-1-yury.norov@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" cpumask_empty() call is O(N) and useless because the previous cpumask_and() returns false for empty 'cpus'. Drop it. CC: Markus Elfring Reviewed-by: Madadi Vineeth Reddy Reviewed-by: K Prateek Nayak Reviewed-by: Vincent Guittot Signed-off-by: Yury Norov (NVIDIA) --- Rebased and re-tested on top of master. Original patch: https://lore.kernel.org/all/20250911023426.457745-1-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 e04f94233cda..af9e9dbdaa6d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8362,9 +8362,7 @@ static int find_energy_efficient_cpu(struct task_stru= ct *p, int prev_cpu) int max_spare_cap_cpu =3D -1; int fits, max_fits =3D -1; =20 - 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; =20 /* Account external pressure for the energy estimation */ --=20 2.43.0