Changes in v4:
- rebased on top of Eric's series
[PATCH v2 00/20] add byte-based block_status driver callbacks
http://lists.nongnu.org/archive/html/qemu-devel/2017-07/msg04370.html
- patch 5 fixed to compile without CONFIG_FALLOCATE and support
BDRV_REQ_ALLOCATE with xfsctl enabled
- add patches 1, 2 to support write/zero flags in mirror and blkverify
drivers
Here goes a revisited series on qcow2 preallocation. It's probably a bit better
integrated this time and the amount of code is reduced significantly.
Changes in v3:
- requests intersection detection from the previous versions is removed
from qcow2 driver. Instead, tracked request infrastructure from the common
block layer is used.
- that made possible to omit preallocation for metadata writes.
Those are rare and won't affect performance.
- 'Simultaneous writes' feature (patches v2 12-15) dropped by now;
Might worth a separate series.
- various remarks to the previous version fixed
- some iotests added
Changes in v2:
- introduce new BDRV flag for write_zeroes()
instead of using driver callback directly.
Skipped introducing new functions like bdrv_co_pallocate() for now:
1. it seems ok to keep calling this write_zeroes() as zeroes
are expected;
2. most of the code can be reused now anyway, so changes to
write_zeroes() path are not significant
3. write_zeroes() alignment and max-request limits can also be reused
As a possible alternative we can have bdrv_co_pallocate() which can
switch to pwrite_zeroes(,flags|=BDRV_REQ_ALLOCATE) early.
This pull request is to address a few performance problems of qcow2 format:
1. non cluster-aligned write requests (to unallocated clusters) explicitly
pad data with zeroes if there is no backing data. This can be avoided
and the whole clusters are preallocated and zeroed in a single
efficient write_zeroes() operation, also providing better host file
continuity
2. moreover, efficient write_zeroes() operation can be used to preallocate
space megabytes ahead which gives noticeable improvement on some storage
types (e.g. distributed storages where space allocation operation is
expensive)
/* omitted in v3: */
3. preallocating/zeroing the clusters in advance makes possible to enable
simultaneous writes to the same unallocated cluster, which is beneficial
for parallel sequential write operations which are not cluster-aligned
Performance test results are added to commit messages (see patch 3, 12)
Anton Nefedov (12):
mirror: inherit supported write/zero flags
blkverify: set supported write/zero flags
block: introduce BDRV_REQ_ALLOCATE flag
block: treat BDRV_REQ_ALLOCATE as serialising
file-posix: support BDRV_REQ_ALLOCATE
block: support BDRV_REQ_ALLOCATE in passthrough drivers
qcow2: set inactive flag
qcow2: move is_zero() up
qcow2: skip writing zero buffers to empty COW areas
qcow2: allocate image space by-cluster
iotest 190: test BDRV_REQ_ALLOCATE
iotest 134: test cluster-misaligned encrypted write
Denis V. Lunev (2):
qcow2: preallocation at image expand
qcow2: truncate preallocated space
Pavel Butsykin (1):
qcow2: check space leak at the end of the image
include/block/block.h | 6 +-
include/block/block_int.h | 2 +-
block/qcow2.h | 18
block/blkdebug.c | 3 +-
block/blkverify.c | 9 ++
block/file-posix.c | 8 ++
block/io.c | 47 +++--
block/mirror.c | 5 +
block/qcow2-cluster.c | 14 ++-
block/qcow2-refcount.c | 7 ++
block/qcow2.c | 203 -
block/raw-format.c | 3 +-
block/trace-events | 1 +
qemu-options.hx| 4 +
tests/qemu-iotests/026.out | 104 ++-
tests/qemu-iotests/026.out.nocache | 104 ++-
tests/qemu-iotests/029.out | 5 +-
tests/qemu-iotests/060 | 2 +-
tests/qemu-iotests/060.out | 13 ++-
tests/qemu-iotests/061.out | 5 +-
tests/qemu-iotests/066 | 2 +-
tests/qemu-iotests/066.out | 9 +-
tests/qemu-iotests/098.out | 7 +-
tests/qemu-iotests/108.out | 5 +-
tests/qemu-iotests/112.out | 5 +-
tests/qemu-iotests/134 | 9 ++
tests/qemu-iotests/134.out | 10 ++
tests/qemu-iotests/190 | 146 ++
tests/qemu-iotests/190.out | 50 +
tests/qemu-iotests/group | 1 +
30 files changed, 705 insertions(+), 102 deletions(-)
create mode 100755 tests/qemu-iotests/190
create mode 100644 tests/qemu-iotests/190.out
--
2.7.4
