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block, bfq: do not raise non-default weights 

BFQ heuristics try to detect interactive I/O, and raise the weight of
the queues containing such an I/O. Yet, if also the user changes the
weight of a queue (i.e., the user changes the ioprio of the process
associated with that queue), then it is most likely better to prevent
BFQ heuristics from silently changing the same weight.

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 19:19:46 +01:00 committed by Jens Axboe
parent ab1fb47e33
commit 91b896f65d
1 changed files with 7 additions and 3 deletions
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10
block/bfq-iosched.c
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@ -1671,15 +1671,19 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd,
* - it is sync,
* - it does not belong to a large burst,
* - it has been idle for enough time or is soft real-time,
* - is linked to a bfq_io_cq (it is not shared in any sense).
* - is linked to a bfq_io_cq (it is not shared in any sense),
* - has a default weight (otherwise we assume the user wanted
* to control its weight explicitly)
*/
in_burst = bfq_bfqq_in_large_burst(bfqq);
soft_rt = bfqd->bfq_wr_max_softrt_rate > 0 &&
!BFQQ_TOTALLY_SEEKY(bfqq) &&
!in_burst &&
time_is_before_jiffies(bfqq->soft_rt_next_start) &&
bfqq->dispatched == 0;
*interactive = !in_burst && idle_for_long_time;
bfqq->dispatched == 0 &&
bfqq->entity.new_weight == 40;
*interactive = !in_burst && idle_for_long_time &&
bfqq->entity.new_weight == 40;
wr_or_deserves_wr = bfqd->low_latency &&
(bfqq->wr_coeff > 1 ||
(bfq_bfqq_sync(bfqq) &&