From: Yafang Shao <laoar.shao@gmail.com>
To: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
eddyz87@gmail.com, memxor@gmail.com, mingo@redhat.com,
peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, akpm@linux-foundation.org,
david@kernel.org, gourry@gourry.net, tj@kernel.org,
hannes@cmpxchg.org, mkoutny@suse.com, shakeel.butt@linux.dev,
roman.gushchin@linux.dev, yu.c.chen@intel.com,
zhao1.liu@intel.com, tim.c.chen@linux.intel.com,
lizhe.67@bytedance.com
Cc: bpf@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, Yafang Shao <laoar.shao@gmail.com>
Subject: [RFC PATCH v3 bpf-next 2/5] sched: use static_branch_likely() for the NUMA balancing tick check
Date: Mon, 19 Oct 2026 14:41:54 +0800 [thread overview]
Message-ID: <20261019064157.29885-3-laoar.shao@gmail.com> (raw)
In-Reply-To: <20261019064157.29885-1-laoar.shao@gmail.com>
task_tick_fair() checks sched_numa_balancing on every tick. The
static_branch_unlikely() annotation reserves the nop for the disabled case,
so the default configuration (NUMA_BALANCING_DEFAULT_ENABLED=y) pays a
taken jump per tick. Flip the polarity to static_branch_likely() so that
the fast path matches the default.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
---
kernel/sched/fair.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 973647ad6c2d..71dc47d6114d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -15351,7 +15351,7 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
if (queued)
return;
- if (static_branch_unlikely(&sched_numa_balancing))
+ if (static_branch_likely(&sched_numa_balancing))
task_tick_numa(rq, curr);
task_tick_cache(rq, curr);
--
2.52.0
next prev parent reply other threads:[~2026-10-19 6:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-19 6:41 [RFC PATCH v3 bpf-next 0/5] BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 1/5] sched: fix stale get_pref_llc() stub for !CONFIG_SCHED_CACHE Yafang Shao
2026-10-19 6:41 ` Yafang Shao [this message]
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 3/5] sched: add helpers for numa balancing Yafang Shao
2026-10-19 7:14 ` bot+bpf-ci
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 4/5] sched: add BPF-based per-cgroup NUMA balancing mode selection Yafang Shao
2026-10-19 7:24 ` bot+bpf-ci
2026-10-19 6:41 ` [RFC PATCH v3 bpf-next 5/5] selftests/bpf: add tests for the numab kfuncs Yafang Shao
2026-10-20 16:54 ` [RFC PATCH v3 bpf-next 0/5] BPF-based per-cgroup NUMA balancing mode selection Tejun Heo
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