block/blk-iocost: collect per-cpu latency stats over possible CPUs

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ioc_lat_stat() walks ioc->pcpu_stat with for_each_online_cpu() to
compute missed-ppm and rq_wait deltas.  An offlined CPU is skipped, so
its delta is dropped from the period and its last_* watermark is not
advanced; on re-online the next collection sees a delta spanning the
whole offline interval, corrupting the latency/vrate picture.

Fixes: 7caa47151a ("blkcg: implement blk-iocost")
Signed-off-by: Tao Cui <cuitao@kylinos.cn>
Reviewed-by: Yu Kuai <yukuai@fygo.io>
Link: https://patch.msgid.link/20260720093726.28965-4-cui.tao@linux.dev
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Tao Cui 2026-07-20 17:37:25 +08:00 • committed by Jens Axboe

parent e0698304bd

commit 4e050c5b92

1 changed files with 1 additions and 1 deletions

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block/blk-iocost.c

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