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Re: [Qemu-devel] [PATCH 24/27] block/parallels: delay writing to BAT til
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH 24/27] block/parallels: delay writing to BAT till bdrv_co_flush_to_os |
Date: |
Wed, 22 Apr 2015 15:16:42 +0100 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Wed, Mar 11, 2015 at 01:28:18PM +0300, Denis V. Lunev wrote:
> The idea is that we do not need to immediately sync BAT to the image as
> from the guest point of view there is a possibility that IO is lost
> even in the physical controller until flush command was finished.
> bdrv_co_flush_to_os is exactly the right place for this purpose.
>
> Technically the patch uses loaded BAT data as a cache and performs
> actual on-disk metadata updates in parallels_co_flush_to_os callback.
>
> This patch speed ups
> qemu-img create -f parallels -o cluster_size=64k ./1.hds 64G
> qemu-io -f parallels -c "write -P 0x11 0 1024k" 1.hds
> writing from 50-60 Mb/sec to 80-90 Mb/sec on rotational media and
> from 160 Mb/sec to 190 Mb/sec on SSD disk.
>
> Signed-off-by: Denis V. Lunev <address@hidden>
> Reviewed-by: Roman Kagan <address@hidden>
> CC: Kevin Wolf <address@hidden>
> CC: Stefan Hajnoczi <address@hidden>
> ---
> block/parallels.c | 50 ++++++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 44 insertions(+), 6 deletions(-)
Reviewed-by: Stefan Hajnoczi <address@hidden>
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- Re: [Qemu-devel] [PATCH 24/27] block/parallels: delay writing to BAT till bdrv_co_flush_to_os,
Stefan Hajnoczi <=