xfs: reduce exclusive locking on unaligned dio
Attempt shared locking for unaligned DIO, but only if the the
underlying extent is already allocated and in written state. On
failure, retry with the existing exclusive locking.
Test case is fio randrw of 512 byte IOs using AIO and an iodepth of
READ: bw=4560KiB/s (4670kB/s), 4560KiB/s-4560KiB/s (4670kB/s-4670kB/s), io=134MiB (140MB), run=30001-30001msec
WRITE: bw=4567KiB/s (4676kB/s), 4567KiB/s-4567KiB/s (4676kB/s-4676kB/s), io=134MiB (140MB), run=30001-30001msec
READ: bw=37.6MiB/s (39.4MB/s), 37.6MiB/s-37.6MiB/s (39.4MB/s-39.4MB/s), io=1127MiB (1182MB), run=30002-30002msec
WRITE: bw=37.6MiB/s (39.4MB/s), 37.6MiB/s-37.6MiB/s (39.4MB/s-39.4MB/s), io=1128MiB (1183MB), run=30002-30002msec
That's an improvement from ~18k IOPS to a ~150k IOPS, which is
about the IOPS limit of the VM block device setup I'm testing on.
4kB block IO comparison:
READ: bw=296MiB/s (310MB/s), 296MiB/s-296MiB/s (310MB/s-310MB/s), io=8868MiB (9299MB), run=30002-30002msec
WRITE: bw=296MiB/s (310MB/s), 296MiB/s-296MiB/s (310MB/s-310MB/s), io=8878MiB (9309MB), run=30002-30002msec
Which is ~150k IOPS, same as what the test gets for sub-block
AIO+DIO writes with this patch.
Signed-off-by: Dave Chinner <firstname.lastname@example.org>
[hch: rebased, split unaligned from nowait]
Signed-off-by: Christoph Hellwig <email@example.com>
Reviewed-by: Brian Foster <firstname.lastname@example.org>
Reviewed-by: Darrick J. Wong <email@example.com>
Signed-off-by: Darrick J. Wong <firstname.lastname@example.org>
2 files changed