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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Mon, 13 Jul 2015 12:17:43 +0200
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Subject: Re: [Qemu-devel] virtio-blk multiqueue support in qemu.
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To: "Michael S. Tsirkin" <mst@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>
Cc: Naredula Janardhana Reddy <naredula.jana@gmail.com>, Fam Zheng <famz@redhat.com>, Ming Lei <ming.lei@canonical.com>, Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org



On 09/07/2015 15:29, Michael S. Tsirkin wrote:
> > On the positive side, we do need something similar to the last 3 patches
> > to expose multiqueue to the guest.  But it will require much more work
> > in QEMU to achieve true multiqueue.
> 
> Might this be useful as an intermediate step, e.g. for testing
> guest code?

Yes, this is already how virtio-scsi multiqueue is implemented.  The
speedup is noticeable.  However, for virtio-blk there is a huge
consumption of interrupt vectors in the guest, so it doesn't scale to
multiple disks as well as virtio-scsi.