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Date: Tue, 5 Aug 2014 11:48:44 +0200
From: Kevin Wolf <kwolf@redhat.com>
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References: <1407209598-2572-1-git-send-email-ming.lei@canonical.com>
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Subject: Re: [Qemu-devel] [PATCH v1 00/17] dataplane: optimization and multi
 virtqueue support
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To: Ming Lei <ming.lei@canonical.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Fam Zheng <famz@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, qemu-devel@nongnu.org, Stefan Hajnoczi <stefanha@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>

Am 05.08.2014 um 05:33 hat Ming Lei geschrieben:
> Hi,
> 
> These patches bring up below 4 changes:
>         - introduce object allocation pool and apply it to
>         virtio-blk dataplane for improving its performance
> 
>         - introduce selective coroutine bypass mechanism
>         for improving performance of virtio-blk dataplane with
>         raw format image

Before applying any bypassing patches, I think we should understand in
detail where we are losing performance with coroutines enabled.

I also think that the device emulation has no business in deciding
whether the bypass is used (it depends solely on conditions outside of
the device) and that leaking the fd number out of raw-posix is wrong.
Both of them are layering violations that shouldn't be reintroduced.

>         - linux-aio changes: fixing for cases of -EAGAIN and partial
>         completion, increase max events to 256, and remove one unuseful
>         fields in 'struct qemu_laiocb'
> 
>         - support multi virtqueue for virtio-blk

Like Stefan said, the series should be split in four, one for each item
in your list, so that each optimisation can be evaluated on its own.

Kevin