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Re: [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image ex
From: |
Roman Karan |
Subject: |
Re: [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion |
Date: |
Tue, 10 Mar 2015 18:10:41 +0300 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Mar 10, 2015 at 11:51:20AM +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%.
Reviewed-by: Roman Kagan <address@hidden>
Roman.
- Re: [Qemu-devel] [PATCH 19/27] block/parallels: implement incorrect close detection, (continued)
- [Qemu-devel] [PATCH 13/27] block/parallels: rename catalog_ names to bat_, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 04/27] block/parallels: read up to cluster end in one go, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 14/27] block/parallels: create bat2sect helper, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 05/27] block/parallels: add get_block_status, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 15/27] block/parallels: keep BAT bitmap data in little endian in memory, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 11/27] iotests, parallels: test for newly created parallels image via qemu-img, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion, Denis V. Lunev, 2015/03/10
- Re: [Qemu-devel] [PATCH 26/27] block/parallels: optimize linear image expansion,
Roman Karan <=
- [Qemu-devel] [PATCH 08/27] block/parallels: _co_writev callback for Parallels format, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 18/27] block/parallels: implement parallels_check method of block driver, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 07/27] block/parallels: replace magic constants 4, 64 with proper sizeofs, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 24/27] block/parallels: delay writing to BAT till bdrv_co_flush_to_os, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 21/27] block/parallels: no need to flush on each block allocation table update, Denis V. Lunev, 2015/03/10
- [Qemu-devel] [PATCH 02/27] block/parallels: rename parallels_header to ParallelsHeader, Denis V. Lunev, 2015/03/10