Kernel/linux
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2025-01-16 18:08:20 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

block, bfq: use half slice_idle as a threshold to check short ttime

Browse Source 
The value of the I/O plugging (idling) timeout is used also as the
think-time threshold to decide whether a process has a short think
time.  In this respect, a good value of this timeout for rotational
drives is un the order of several ms. Yet, this is often too long a
time interval to be effective as a think-time threshold. This commit
mitigates this problem (by a lot, according to tests), by halving the
threshold.

Tested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Paolo Valente 2021-01-22 19:19:43 +01:00 committed by Jens Axboe
parent a33df75c63
commit b5f74ecacc
1 changed files with 4 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
block/bfq-iosched.c
View File

@ -5238,12 +5238,13 @@ static void bfq_update_has_short_ttime(struct bfq_data *bfqd,
return;
/* Think time is infinite if no process is linked to
* bfqq. Otherwise check average think time to
* decide whether to mark as has_short_ttime
* bfqq. Otherwise check average think time to decide whether
* to mark as has_short_ttime. To this goal, compare average
* think time with half the I/O-plugging timeout.
*/
if (atomic_read(&bic->icq.ioc->active_ref) == 0 ||
(bfq_sample_valid(bfqq->ttime.ttime_samples) &&
bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle))
bfqq->ttime.ttime_mean > bfqd->bfq_slice_idle>>1))
has_short_ttime = false;
state_changed = has_short_ttime != bfq_bfqq_has_short_ttime(bfqq);