Merged bfq_queues are kept out of weight-raising (low-latency) mechanisms. The reason is that these queues are usually created for non-interactive and non-soft-real-time tasks. Yet this is not the case for stably-merged queues. These queues are merged just because they are created shortly after each other. So they may easily serve the I/O of an interactive or soft-real time application, if the application happens to spawn multiple processes. To address this issue, this commits lets also stably-merged queued enjoy weight raising. Signed-off-by: Paolo Valente <paolo.valente@xxxxxxxxxx> --- block/bfq-iosched.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index acd1f881273e..da2363f12e53 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -1729,10 +1729,23 @@ static void bfq_bfqq_handle_idle_busy_switch(struct bfq_data *bfqd, bfqq->entity.new_weight == 40; *interactive = !in_burst && idle_for_long_time && bfqq->entity.new_weight == 40; + /* + * Merged bfq_queues are kept out of weight-raising + * (low-latency) mechanisms. The reason is that these queues + * are usually created for non-interactive and + * non-soft-real-time tasks. Yet this is not the case for + * stably-merged queues. These queues are merged just because + * they are created shortly after each other. So they may + * easily serve the I/O of an interactive or soft-real time + * application, if the application happens to spawn multiple + * processes. So let also stably-merged queued enjoy weight + * raising. + */ wr_or_deserves_wr = bfqd->low_latency && (bfqq->wr_coeff > 1 || (bfq_bfqq_sync(bfqq) && - bfqq->bic && (*interactive || soft_rt))); + (bfqq->bic || RQ_BIC(rq)->stably_merged) && + (*interactive || soft_rt))); /* * Using the last flag, update budget and check whether bfqq -- 2.20.1
