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@xxxxxxx> Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx> --- block/bfq-iosched.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 9e4eb0fc1c16..eb2ca32d5b63 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -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); -- 2.20.1
