block, bfq: re-evaluate convenience of I/O plugging on rq arrivals
Upon an I/O-dispatch attempt, BFQ may detect that it was better to plug I/O dispatch, and to wait for a new request to arrive for the currently in-service queue. But the arrival of a new request for an empty bfq_queue, and thus the switch from idle to busy of the bfq_queue, may cause the scenario to change, and make plugging no longer needed for service guarantees, or more convenient for throughput. In this case, keeping I/O-dispatch plugged would certainly lower throughput. To address this issue, this commit makes such a check, and stops plugging I/O if it is better to stop plugging I/O. Tested-by:Jan Kara <jack@suse.cz> Signed-off-by:
Paolo Valente <paolo.valente@linaro.org> Signed-off-by:
Jens Axboe <axboe@kernel.dk>
parent
eb2fd80f
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