Missing qemu-block@, CCing.
On 06/01/2017 11:14 AM, Anton Nefedov wrote:
> 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)
>
> 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 (11):
> block: introduce BDRV_REQ_ALLOCATE flag
> file-posix: support BDRV_REQ_ALLOCATE
> blkdebug: support BDRV_REQ_ALLOCATE
> qcow2: do not COW the empty areas
> qcow2: set inactive flag
> qcow2: handle_prealloc(): find out if area zeroed by earlier
> preallocation
> qcow2: fix misleading comment about L2 linking
> qcow2-cluster: slightly refactor handle_dependencies()
> qcow2-cluster: make handle_dependencies() logic easier to follow
> qcow2: allow concurrent unaligned writes to the same clusters
> iotest 046: test simultaneous cluster write error case
>
> Denis V. Lunev (3):
> qcow2: alloc space for COW in one chunk
> qcow2: preallocation at image expand
> qcow2: truncate preallocated space
>
> Pavel Butsykin (1):
> qcow2: check space leak at the end of the image
>
> block/blkdebug.c | 3 +-
> block/file-posix.c | 9 +-
> block/io.c | 19 ++-
> block/qcow2-cache.c | 3 +
> block/qcow2-cluster.c | 218 +++++++++++++++++++++++------
> block/qcow2-refcount.c | 21 +++
> block/qcow2.c | 273 ++++++++++++++++++++++++++++++++++++-
> block/qcow2.h | 26 ++++
> block/trace-events | 1 +
> include/block/block.h | 6 +-
> tests/qemu-iotests/026.out | 104 ++++++++++----
> tests/qemu-iotests/026.out.nocache | 104 ++++++++++----
> tests/qemu-iotests/029.out | 5 +-
> tests/qemu-iotests/046 | 38 +++++-
> tests/qemu-iotests/046.out | 23 ++++
> 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 +-
> 23 files changed, 789 insertions(+), 112 deletions(-)
>