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From: Ming Lin <mlin@kernel.org>
Date: Tue, 01 Dec 2015 08:26:11 -0800
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Subject: Re: [Qemu-devel] [RFC PATCH 0/9] vhost-nvme: new qemu nvme backend
 using nvme target
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, Christoph Hellwig <hch@lst.de>, linux-nvme@lists.infradead.org, virtualization@lists.linux-foundation.org

On Tue, 2015-12-01 at 17:02 +0100, Paolo Bonzini wrote:
> 
> On 01/12/2015 00:20, Ming Lin wrote:
> > qemu-nvme: 148MB/s
> > vhost-nvme + google-ext: 230MB/s
> > qemu-nvme + google-ext + eventfd: 294MB/s
> > virtio-scsi: 296MB/s
> > virtio-blk: 344MB/s
> > 
> > "vhost-nvme + google-ext" didn't get good enough performance.
> 
> I'd expect it to be on par of qemu-nvme with ioeventfd but the question
> is: why should it be better?  For vhost-net, the answer is that more
> zerocopy can be done if you put the data path in the kernel.
> 
> But qemu-nvme is already using io_submit for the data path, perhaps
> there's not much to gain from vhost-nvme...

What do you think about virtio-nvme+vhost-nvme?
I also have patch for vritio-nvme:
https://git.kernel.org/cgit/linux/kernel/git/mlin/linux.git/log/?h=nvme-split/virtio

Just need to change vhost-nvme to work with it.

> 
> Paolo
> 
> > Still tuning.