diff options
| author | Tahsin Erdogan <tahsin@google.com> | 2015-05-19 13:55:21 -0700 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2016-06-08 11:09:44 +0800 |
| commit | 1ed2eb01dcc5fbb53bd651dcf1c0a69999958542 (patch) | |
| tree | a257a577a71766b9c54352d4e1f13d4a08fc81a0 | |
| parent | e33a13c6a5fdc00833b0067d0f65e7db71e20de6 (diff) | |
block: Make CFQ default to IOPS mode on SSDs
CFQ idling causes reduced IOPS throughput on non-rotational disks.
Since disk head seeking is not applicable to SSDs, it doesn't really
help performance by anticipating future near-by IO requests.
By turning off idling (and switching to IOPS mode), we allow other
processes to dispatch IO requests down to the driver and so increase IO
throughput.
Following FIO benchmark results were taken on a cloud SSD offering with
idling on and off:
Idling iops avg-lat(ms) stddev bw
------------------------------------------------------
On 7054 90.107 38.697 28217KB/s
Off 29255 21.836 11.730 117022KB/s
fio --name=temp --size=100G --time_based --ioengine=libaio \
--randrepeat=0 --direct=1 --invalidate=1 --verify=0 \
--verify_fatal=0 --rw=randread --blocksize=4k --group_reporting=1 \
--filename=/dev/sdb --runtime=10 --iodepth=64 --numjobs=10
And the following is from a local SSD run:
Idling iops avg-lat(ms) stddev bw
------------------------------------------------------
On 19320 33.043 14.068 77281KB/s
Off 21626 29.465 12.662 86507KB/s
fio --name=temp --size=5G --time_based --ioengine=libaio \
--randrepeat=0 --direct=1 --invalidate=1 --verify=0 \
--verify_fatal=0 --rw=randread --blocksize=4k --group_reporting=1 \
--filename=/fio_data --runtime=10 --iodepth=64 --numjobs=10
Reviewed-by: Nauman Rafique <nauman@google.com>
Signed-off-by: Tahsin Erdogan <tahsin@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
(cherry picked from commit 41c0126b3f22ef36b97b3c38b8f29569848a5ce2)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
| -rw-r--r-- | block/cfq-iosched.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 1f9093e901da..99c6872787b4 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -4578,7 +4578,7 @@ static int cfq_init_queue(struct request_queue *q, struct elevator_type *e) cfqd->cfq_slice[1] = cfq_slice_sync; cfqd->cfq_target_latency = cfq_target_latency; cfqd->cfq_slice_async_rq = cfq_slice_async_rq; - cfqd->cfq_slice_idle = cfq_slice_idle; + cfqd->cfq_slice_idle = blk_queue_nonrot(q) ? 0 : cfq_slice_idle; cfqd->cfq_group_idle = cfq_group_idle; cfqd->cfq_latency = 1; cfqd->hw_tag = -1; |