From: Tao Cui <cui.tao@linux.dev>
To: Jens Axboe <axboe@kernel.dk>
Cc: Tejun Heo <tj@kernel.org>, Josef Bacik <josef@toxicpanda.com>,
Omar Sandoval <osandov@fb.com>,
Bart Van Assche <bvanassche@acm.org>, Yu Kuai <yukuai@fygo.io>,
Chaitanya Kulkarni <kch@nvidia.com>,
Hannes Reinecke <hare@kernel.org>, Ming Lei <ming.lei@redhat.com>,
Damien Le Moal <dlemoal@kernel.org>,
Nilay Shroff <nilay@linux.ibm.com>,
linux-block@vger.kernel.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, cui.tao@linux.dev,
cuitao@kylinos.cn
Subject: [PATCH 4/4] block/kyber-iosched: flush per-cpu latency buckets over possible CPUs
Date: Mon, 20 Jul 2026 17:37:26 +0800 [thread overview]
Message-ID: <20260720093726.28965-5-cui.tao@linux.dev> (raw)
In-Reply-To: <20260720093726.28965-1-cui.tao@linux.dev>
From: Tao Cui <cuitao@kylinos.cn>
kyber_timer_fn() sums the per-cpu latency histograms with
for_each_online_cpu(). A CPU that goes offline mid-interval leaves its
bucket un-flushed; the samples are lost from the current decision and
re-appear (stale) when the CPU is onlined again.
Fixes: 6e25cb01ea20 ("kyber: implement improved heuristics")
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
---
block/kyber-iosched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index 971818bcdc9d..2ee552ab8135 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -275,7 +275,7 @@ static void kyber_timer_fn(struct timer_list *t)
bool bad = false;
/* Sum all of the per-cpu latency histograms. */
- for_each_online_cpu(cpu) {
+ for_each_possible_cpu(cpu) {
struct kyber_cpu_latency *cpu_latency;
cpu_latency = per_cpu_ptr(kqd->cpu_latency, cpu);
--
2.43.0
prev parent reply other threads:[~2026-07-20 9:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-20 9:37 [PATCH 0/4] block: drain per-cpu latency stats over possible CPUs Tao Cui
2026-07-20 9:37 ` [PATCH 1/4] block/blk-stat: drain per-cpu callback " Tao Cui
2026-07-20 9:37 ` [PATCH 2/4] block/blk-iolatency: account per-cpu latency " Tao Cui
2026-07-20 9:37 ` [PATCH 3/4] block/blk-iocost: collect " Tao Cui
2026-07-20 9:37 ` Tao Cui [this message]
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