Re: [PATCH 0/6][RFC] virtio-blk: Change I/O path from request to BIO

[Rusty Russell]

On Wed, 21 Dec 2011 10:00:48 +0900, Minchan Kim <minchan@xxxxxxxxxx> 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 :)

I can find the source to aio-stress, but no obvious clues.

Help!
Rusty.
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