[PATCH 3/4] block/blk-iocost: collect per-cpu latency stats over possible CPUs
Tao Cui <[email protected]>
| Newsgroups | org.kernel.vger.cgroups,org.kernel.vger.linux-block,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
From: Tao Cui <[email protected]> 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: 7caa47151ab2 ("blkcg: implement blk-iocost") Signed-off-by: Tao Cui <[email protected]> --- block/blk-iocost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/blk-iocost.c b/block/blk-iocost.c index 8b2aeba2e1e3..b60625613e09 100644 --- a/block/blk-iocost.c +++ b/block/blk-iocost.c @@ -1592,7 +1592,7 @@ static void ioc_lat_stat(struct ioc *ioc, u32 *missed_ppm_ar, u32 *rq_wait_pct_p u64 rq_wait_ns = 0; int cpu, rw; - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { struct ioc_pcpu_stat *stat = per_cpu_ptr(ioc->pcpu_stat, cpu); u64 this_rq_wait_ns; -- 2.43.0