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SubjectRe: [PATCH 0/6][RFC] virtio-blk: Change I/O path from request to BIO
Hi Rusty,

On Wed, Dec 21, 2011 at 03:38:03PM +1030, Rusty Russell wrote:
> On Wed, 21 Dec 2011 10:00:48 +0900, Minchan Kim <minchan@kernel.org> wrote:
> > This patch is follow-up of Christohp Hellwig's work
> > [RFC: ->make_request support for virtio-blk].
> > http://thread.gmane.org/gmane.linux.kernel/1199763
> >
> > Quote from hch
> > "This patchset allows the virtio-blk driver to support much higher IOP
> > rates which can be driven out of modern PCI-e flash devices. At this
> > point it really is just a RFC due to various issues."
> >
> > I fixed race bug and add batch I/O for enhancing sequential I/O,
> > FLUSH/FUA emulation.
> >
> > I tested this patch on fusion I/O device by aio-stress.
> > Result is following as.
> >
> > Benchmark : aio-stress (64 thread, test file size 512M, 8K io per IO, O_DIRECT write)
> > Environment: 8 socket - 8 core, 2533.372Hz, Fusion IO 320G storage
> > Test repeated by 20 times
> > Guest I/O scheduler : CFQ
> > Host I/O scheduler : NOOP
> >
> > Request BIO(patch 1-4) BIO-batch(patch 1-6)
> > (MB/s) stddev (MB/s) stddev (MB/s) stddev
> > w 737.820 4.063 613.735 31.605 730.288 24.854
> > rw 208.754 20.450 314.630 37.352 317.831 41.719
> > r 770.974 2.340 347.483 51.370 750.324 8.280
> > rr 250.391 16.910 350.053 29.986 325.976 24.846
>
> So, you dropped w and r down 2%, but rw and rr up 40%.
>
> If I knew what the various rows were, I'd have something intelligent to
> say, I'm sure :)

Sorry for missing that.

w: Sequential Write
rw: Random Write
r: Sequential Read
rr: Random Read

>
> I can find the source to aio-stress, but no obvious clues.
>
> Help!
> Rusty.

--
Kind regards,
Minchan Kim


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