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Date: Tue, 27 Oct 2015 10:04:02 +0800
From: Fam Zheng <famz@redhat.com>
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Subject: Re: [Qemu-devel] 4k seq read splitting for virtio-blk - possible
 workarounds?
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>, Andrey Korolyov <andrey@xdel.ru>, Peter Lieven <pl@kamp.de>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, Jeff Moyer <jmoyer@redhat.com>, Sergey Fionov <fionov@gmail.com>

On Mon, 10/26 18:32, Paolo Bonzini wrote:
> Having a "real" multiqueue model in the host (real = one I/O thread and
> one AIO context per guest queue, with each I/O thread able to service
> multiple disks; rather than a "fake" multiqueue where you still have one
> I/O thread and AIO context per guest disk, so all the queues really
> funnel into one in the host) should fix this, but it's at least a few
> months away in QEMU... probably something like QEMU 2.8.  My plan is for
> 2.6 to have fine-grained critical sections (patches written, will repost
> during 2.5 hard freeze), 2.7 (unlikely 2.6) to have fine-grained locks,
> and 2.8 or 2.9 to have multiqueue.

Paolo,

You're talking about virtio-scsi, right? What about virtio-blk? Do you think we
should resume the "fake" virtio-blk multiqueue work on QEMU side?

Thanks,
Fam