Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-17 Thread Anton Nefedov
On 14/12/2018 7:20 PM, Vladimir Sementsov-Ogievskiy wrote: > 03.12.2018 13:14, Anton Nefedov wrote: >> If COW areas of the newly allocated clusters are zeroes on the backing image, >> efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole >> cluster instead of writing expli

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-14 Thread Vladimir Sementsov-Ogievskiy
03.12.2018 13:14, Anton Nefedov wrote: > If COW areas of the newly allocated clusters are zeroes on the backing image, > efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole > cluster instead of writing explicit zero buffers later in perform_cow(). > > iotest 060: > write

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-13 Thread Anton Nefedov
On 13/12/2018 3:02 PM, Vladimir Sementsov-Ogievskiy wrote: > 03.12.2018 13:14, Anton Nefedov wrote: >> If COW areas of the newly allocated clusters are zeroes on the backing image, >> efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole >> cluster instead of writing explici

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-13 Thread Vladimir Sementsov-Ogievskiy
03.12.2018 13:14, Anton Nefedov wrote: > If COW areas of the newly allocated clusters are zeroes on the backing image, > efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole > cluster instead of writing explicit zero buffers later in perform_cow(). > [...] > --- a/block/

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-05 Thread Vladimir Sementsov-Ogievskiy
05.12.2018 19:59, Anton Nefedov wrote: > On 5/12/2018 5:01 PM, Vladimir Sementsov-Ogievskiy wrote: >> 03.12.2018 13:14, Anton Nefedov wrote: >>> If COW areas of the newly allocated clusters are zeroes on the backing >>> image, >>> efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-05 Thread Anton Nefedov
On 5/12/2018 5:01 PM, Vladimir Sementsov-Ogievskiy wrote: > 03.12.2018 13:14, Anton Nefedov wrote: >> If COW areas of the newly allocated clusters are zeroes on the backing image, >> efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole >> cluster instead of writing explicit

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-05 Thread Vladimir Sementsov-Ogievskiy
03.12.2018 13:14, Anton Nefedov wrote: > If COW areas of the newly allocated clusters are zeroes on the backing image, > efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole > cluster instead of writing explicit zero buffers later in perform_cow(). > > iotest 060: > write

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-03 Thread Anton Nefedov
On 3/12/2018 4:59 PM, Alberto Garcia wrote: > On Mon 03 Dec 2018 11:14:59 AM CET, Anton Nefedov wrote: >> --- a/qapi/block-core.json >> +++ b/qapi/block-core.json >> @@ -3004,6 +3004,8 @@ >> # >> # @cor_write: a write due to copy-on-read (since 2.11) >> # >> +# @cluster_alloc_space: an allo

Re: [Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-03 Thread Alberto Garcia
On Mon 03 Dec 2018 11:14:59 AM CET, Anton Nefedov wrote: > --- a/qapi/block-core.json > +++ b/qapi/block-core.json > @@ -3004,6 +3004,8 @@ > # > # @cor_write: a write due to copy-on-read (since 2.11) > # > +# @cluster_alloc_space: an allocation of file space for a cluster (since 4.0) Since 4.0

[Qemu-devel] [PATCH v10 8/9] qcow2: skip writing zero buffers to empty COW areas

2018-12-03 Thread Anton Nefedov
If COW areas of the newly allocated clusters are zeroes on the backing image, efficient bdrv_write_zeroes(flags=BDRV_REQ_ALLOCATE) can be used on the whole cluster instead of writing explicit zero buffers later in perform_cow(). iotest 060: write to the discarded cluster does not trigger COW anymo