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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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