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Re: [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image ex
From: |
Roman Kagan |
Subject: |
Re: [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion |
Date: |
Tue, 28 Apr 2015 14:00:54 +0300 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Apr 28, 2015 at 10:46:59AM +0300, Denis V. Lunev wrote:
> Plain image expansion spends a lot of time to update image file size.
> This seriously affects the performance. The following simple test
> qemu_img create -f parallels -o cluster_size=64k ./1.hds 64G
> qemu_io -n -c "write -P 0x11 0 1024M" ./1.hds
> could be improved if the format driver will pre-allocate some space
> in the image file with a reasonable chunk.
>
> This patch preallocates 128 Mb using bdrv_write_zeroes, which should
> normally use fallocate() call inside. Fallback to older truncate()
> could be used as a fallback using image open options thanks to the
> previous patch.
>
> The benefit is around 15%.
>
> Signed-off-by: Denis V. Lunev <address@hidden>
> Reviewed-by: Roman Karan <address@hidden>
s/Karan/Kagan/
> CC: Kevin Wolf <address@hidden>
> CC: Stefan Hajnoczi <address@hidden>
> ---
> block/parallels.c | 42 ++++++++++++++++++++++++++++++++----------
> 1 file changed, 32 insertions(+), 10 deletions(-)
Roman.
- [Qemu-devel] [PATCH 19/27] block/parallels: implement parallels_check method of block driver, (continued)
- [Qemu-devel] [PATCH 19/27] block/parallels: implement parallels_check method of block driver, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 20/27] block/parallels: implement incorrect close detection, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 22/27] block/parallels: improve image reading performance, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 21/27] iotests, parallels: check for incorrectly closed image in tests, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 23/27] block/parallels: create bat_entry_off helper, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 24/27] block/parallels: delay writing to BAT till bdrv_co_flush_to_os, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 25/27] block/parallels: add prealloc-mode and prealloc-size open paramemets, Denis V. Lunev, 2015/04/28
- [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion, Denis V. Lunev, 2015/04/28
- Re: [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion,
Roman Kagan <=
- [Qemu-devel] [PATCH 27/27] block/parallels: improve image writing performance further, Denis V. Lunev, 2015/04/28