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Re: [Qemu-devel] [RFC PATCH v2 00/23] qcow2: Delayed COW
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [RFC PATCH v2 00/23] qcow2: Delayed COW |
Date: |
Thu, 14 Feb 2013 14:35:01 +0100 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Thu, Feb 14, 2013 at 11:56:34AM +0100, Kevin Wolf wrote:
> Am 14.02.2013 11:43, schrieb Stefan Hajnoczi:
> > On Wed, Feb 13, 2013 at 02:21:50PM +0100, Kevin Wolf wrote:
> >> iozone results with and without this series show significant difference
> >> for allocating writes:
> >>
> >> random random
> >> KB reclen write rewrite read reread read write
> >>
> >> base 65536 8 1727 1945 12546 12539 2449 1836
> >> patch 65536 8 1934 1949 12263 12521 2463 1796
> >>
> >> base 1048576 256 22344 38437 105823 106135 37743 32167
> >> patch 1048576 256 35989 38542 105231 105994 38301 33036
> >
> > I imagine the benefit is even greater for 4 KB or 8 KB blocksize?
>
> The upper two lines are 8k block size. I suspect that the benefit would
> be the greatest for misaligned 64k writes, then you have one overlapping
> allocation for each issued request.
I see. I haven't looked at IOzone output for too long, forgot how to
interpret it.
Stefan
- [Qemu-devel] [RFC PATCH v2 17/23] qcow2: Move COW and L2 update into own coroutine, (continued)
- [Qemu-devel] [RFC PATCH v2 17/23] qcow2: Move COW and L2 update into own coroutine, Kevin Wolf, 2013/02/13
- [Qemu-devel] [RFC PATCH v2 22/23] qcow2: Move cluster gathering to a non-looping loop, Kevin Wolf, 2013/02/13
- [Qemu-devel] [RFC PATCH v2 21/23] qemu-iotests: Another concurrent multicluster allocation case, Kevin Wolf, 2013/02/13
- [Qemu-devel] [RFC PATCH v2 20/23] qcow2: Cancel COW when overwritten, Kevin Wolf, 2013/02/13
- [Qemu-devel] [RFC PATCH v2 23/23] qcow2: Gather clusters in a looping loop, Kevin Wolf, 2013/02/13
- Re: [Qemu-devel] [RFC PATCH v2 00/23] qcow2: Delayed COW, Stefan Hajnoczi, 2013/02/14
- Re: [Qemu-devel] [RFC PATCH v2 00/23] qcow2: Delayed COW, Stefan Hajnoczi, 2013/02/18