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blk-mq: complete polled requests directly

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Even for single queue devices there is no point in offloading a polled
completion to the softirq, given that blk_mq_force_complete_rq is called
from the polling thread in that case and thus there are no starvation
issues.

Reviewed-by: Daniel Wagner <dwagner@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2020-06-11 08:44:44 +02:00 committed by Jens Axboe
parent dea6f39938
commit 6aab1da603
1 changed files with 11 additions and 6 deletions
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17
block/blk-mq.c
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@ -703,6 +703,16 @@ void blk_mq_force_complete_rq(struct request *rq)
int cpu; int cpu;
WRITE_ONCE(rq->state, MQ_RQ_COMPLETE); WRITE_ONCE(rq->state, MQ_RQ_COMPLETE);
/*
* For a polled request, always complete locallly, it's pointless
* to redirect the completion.
*/
if (rq->cmd_flags & REQ_HIPRI) {
q->mq_ops->complete(rq);
return;
}
/* /*
* Most of single queue controllers, there is only one irq vector * Most of single queue controllers, there is only one irq vector
* for handling IO completion, and the only irq's affinity is set * for handling IO completion, and the only irq's affinity is set
@ -717,12 +727,7 @@ void blk_mq_force_complete_rq(struct request *rq)
return; return;
} }
/* if (!test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
* For a polled request, always complete locallly, it's pointless
* to redirect the completion.
*/
if ((rq->cmd_flags & REQ_HIPRI) ||
!test_bit(QUEUE_FLAG_SAME_COMP, &q->queue_flags)) {
q->mq_ops->complete(rq); q->mq_ops->complete(rq);
return; return;
} }