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Date: Tue, 01 Jul 2014 19:06:42 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3 0/3] linux-aio: introduce submit I/O at
	batch
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To: Ming Lei <ming.lei@canonical.com>, Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>

Il 01/07/2014 18:35, Ming Lei ha scritto:
> Hi,
>
> The commit 580b6b2aa2(dataplane: use the QEMU block layer for I/O)
> introduces ~40% throughput regression on virtio-blk dataplane, and
> one of causes is that submitting I/O at batch is removed.
>
> This patchset trys to introduce this mechanism on block, at least,
> linux-aio can benefit from that.
>
> With these patches, it is observed that thoughout on virtio-blk
> dataplane can be improved a lot, see data in commit log of patch
> 3/3.
>
> It should be possible to apply the batch mechanism to other devices
> (such as virtio-scsi) too.
>
> V3:
> 	- only support submitting I/O at batch for raw format, pointed by
> 	Kevin

As I commented in the review, I would like evidence that this is 
necessary.  It should work for all formats IMO.

Paolo