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| author |   Josef Bacik <josef@toxicpanda.com> | 2018-09-28 13:45:41 -0400 |
|---|---|---|
| committer |   Jens Axboe <axboe@kernel.dk> | 2018-09-28 11:47:29 -0600 |
| commit | 22ed8a93adc7a9cbb2c0a0fc1d7f10068a1f84c1 (patch) | |
| tree | 2e1b6b870178f979740217aad4a0644c69a3811b /block | |
| parent | blk-iolatency: deal with nr_requests == 1 (diff) | |
| download | linux-dev-22ed8a93adc7a9cbb2c0a0fc1d7f10068a1f84c1.tar.xz linux-dev-22ed8a93adc7a9cbb2c0a0fc1d7f10068a1f84c1.zip | |
blk-iolatency: deal with small samples
There is logic to keep cgroups that haven't done a lot of IO in the most
recent scale window from being punished for over-active higher priority
groups. However for things like ssd's where the windows are pretty
short we'll end up with small numbers of samples, so 5% of samples will
come out to 0 if there aren't enough. Make the floor 1 sample to keep
us from improperly bailing out of scaling down.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-iolatency.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index 8daea7a4fe49..e7be77b0ce8b 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -366,7 +366,7 @@ static void check_scale_change(struct iolatency_grp *iolat) * scale down event. */ samples_thresh = lat_info->nr_samples * 5; - samples_thresh = div64_u64(samples_thresh, 100); + samples_thresh = max(1ULL, div64_u64(samples_thresh, 100)); if (iolat->nr_samples <= samples_thresh) return; } |