[PATCH 2/4] block/blk-iolatency: account 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]> iolatency_check_latencies() and iolatency_ssd_stat() iterate a blkg's per-cpu latency stats with for_each_online_cpu(). When a CPU that has accumulated io.latency samples goes offline, its bucket is skipped: the check loop (which also resets) neither sums nor clears it, and the show path under-reports. On re-online the stranded samples are flushed into a later check window, which can trigger a spurious throttle/scale adjustment. Fixes: d70675121546 ("block: introduce blk-iolatency io controller") Fixes: 1fa2840e56f9 ("blk-iolatency: use a percentile approache for ssd's") Signed-off-by: Tao Cui <[email protected]> --- block/blk-iolatency.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 1cc33aa0b669..d6c401d6174c 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -523,7 +523,7 @@ static void iolatency_check_latencies(struct iolatency_grp *iolat, u64 now) latency_stat_init(iolat, &stat); preempt_disable(); - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { struct latency_stat *s; s = per_cpu_ptr(iolat->stats, cpu); latency_stat_sum(iolat, &stat, s); @@ -924,7 +924,7 @@ static void iolatency_ssd_stat(struct iolatency_grp *iolat, struct seq_file *s) latency_stat_init(iolat, &stat); preempt_disable(); - for_each_online_cpu(cpu) { + for_each_possible_cpu(cpu) { struct latency_stat *s; s = per_cpu_ptr(iolat->stats, cpu); latency_stat_sum(iolat, &stat, s); -- 2.43.0