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| author | Paolo Valente <paolo.valente@linaro.org> | 2017-04-12 18:23:19 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2017-04-19 08:30:26 -0600 |
| commit | e01eff01d5c81f4dbba186299b16b08aa7316d5b (patch) | |
| tree | 9a6cd957d0ca463247d3e57438cfec5e2702a661 /block | |
| parent | bf2b79e7c4b312aa6e1c661fb27e0dc4dd42f2c2 (diff) | |
| download | lwn-e01eff01d5c81f4dbba186299b16b08aa7316d5b.tar.gz lwn-e01eff01d5c81f4dbba186299b16b08aa7316d5b.zip | |
block, bfq: boost the throughput with random I/O on NCQ-capable HDDs
This patch is basically the counterpart, for NCQ-capable rotational
devices, of the previous patch. Exactly as the previous patch does on
flash-based devices and for any workload, this patch disables device
idling on rotational devices, but only for random I/O. In fact, only
with these queues disabling idling boosts the throughput on
NCQ-capable rotational devices. To not break service guarantees,
idling is disabled for NCQ-enabled rotational devices only when the
same symmetry conditions considered in the previous patches hold.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/bfq-iosched.c | 16 |
1 files changed, 6 insertions, 10 deletions
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 208178478dc4..549f030509ef 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6439,20 +6439,15 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) * The next variable takes into account the cases where idling * boosts the throughput. * - * The value of the variable is computed considering that - * idling is usually beneficial for the throughput if: + * The value of the variable is computed considering, first, that + * idling is virtually always beneficial for the throughput if: * (a) the device is not NCQ-capable, or * (b) regardless of the presence of NCQ, the device is rotational - * and the request pattern for bfqq is I/O-bound (possible - * throughput losses caused by granting idling to seeky queues - * are mitigated by the fact that, in all scenarios where - * boosting throughput is the best thing to do, i.e., in all - * symmetric scenarios, only a minimal idle time is allowed to - * seeky queues). + * and the request pattern for bfqq is I/O-bound and sequential. * * Secondly, and in contrast to the above item (b), idling an * NCQ-capable flash-based device would not boost the - * throughput even with intense I/O; rather it would lower + * throughput even with sequential I/O; rather it would lower * the throughput in proportion to how fast the device * is. Accordingly, the next variable is true if any of the * above conditions (a) and (b) is true, and, in particular, @@ -6460,7 +6455,8 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq) * device. */ idling_boosts_thr = !bfqd->hw_tag || - (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq)); + (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) && + bfq_bfqq_idle_window(bfqq)); /* * The value of the next variable, |