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[188.141.5.72]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-483c3b3474dsm66363585e9.1.2026.02.26.14.44.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Feb 2026 14:44:28 -0800 (PST) From: David Carlier To: Tejun Heo , David Vernet Cc: linux-kernel@vger.kernel.org, David Carlier Subject: [PATCH] sched_ext: add unlikely() hints in do_enqueue_task() hot path Date: Thu, 26 Feb 2026 22:44:25 +0000 Message-ID: <20260226224425.8819-1-devnexen@gmail.com> X-Mailer: git-send-email 2.51.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add unlikely() branch hints to the scx_rq_online() and scx_rq_bypassing() checks in do_enqueue_task() that are rarely taken during normal operation. The PF_EXITING and migration_disabled checks are left unchanged as the existing code already places unlikely() precisely on the runtime condition. Signed-off-by: David Carlier --- kernel/sched/ext.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index c18e81e8ef51..9a888ce5e2f1 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -1360,10 +1360,10 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags, * is offline and are just running the hotplug path. Don't bother the * BPF scheduler. */ - if (!scx_rq_online(rq)) + if (unlikely(!scx_rq_online(rq))) goto local; - if (scx_rq_bypassing(rq)) { + if (unlikely(scx_rq_bypassing(rq))) { __scx_add_event(sch, SCX_EV_BYPASS_DISPATCH, 1); goto bypass; } -- 2.51.0