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| author | Mikulas Patocka | 2011-01-13 20:59:47 +0100 |
|---|---|---|
| committer | Alasdair G Kergon | 2011-01-13 20:59:47 +0100 |
| commit | d9bf0b508ddfe19883b982b29a03c02ccbf53806 (patch) | |
| tree | 815334dee3eabcf0cc35cd23928cc456c0212d2d /drivers/md/dm-ioctl.c | |
| parent | dm mpath: disable blk_abort_queue (diff) | |
| download | kernel-qcow2-linux-d9bf0b508ddfe19883b982b29a03c02ccbf53806.tar.gz kernel-qcow2-linux-d9bf0b508ddfe19883b982b29a03c02ccbf53806.tar.xz kernel-qcow2-linux-d9bf0b508ddfe19883b982b29a03c02ccbf53806.zip | |
dm io: remove BIO_RW_SYNCIO flag from kcopyd
Remove the REQ_SYNC flag to improve write throughput when writing
to the origin with a snapshot on the same device (using the CFQ I/O
scheduler).
Sequential write throughput (chunksize of 4k, 32k, 512k)
unpatched: 8.5, 8.6, 9.3 MB/s
patched: 15.2, 18.5, 17.5 MB/s
Snapshot exception reallocations are triggered by writes that are
usually async, so mark the associated dm_io_request as async as well.
This helps when using the CFQ I/O scheduler because it has separate
queues for sync and async I/O. Async is optimized for throughput; sync
for latency. With this change we're consciously favoring throughput over
latency.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Diffstat (limited to 'drivers/md/dm-ioctl.c')
0 files changed, 0 insertions, 0 deletions