Re: [Qemu-devel] Block I/O optimizations

[Abel Gordon]

Stefan Hajnoczi <address@hidden>  wrote on 01/03/2013 12:54:54 PM:

> On Thu, Feb 28, 2013 at 08:20:08PM +0200, Abel Gordon wrote:
> > Stefan Hajnoczi <address@hidden> wrote on 28/02/2013 04:43:04 PM:
> > > I think extending and tuning the existing mechanisms is the way to
go.
> > > I don't see obvious advantages other than reducing context switches.
> >
> > Maybe it is worth checking...
> > We did experiments using vhost-net and vhost-blk. We measured and
compared
> > the traditional model (kernel thread per VM/virtual device) to the
> > shared-thread model with fine-grained I/O scheduling (single kernel
thread
> > used to serve multiple VMs). We noticed improvements up-to 2.5x
> > in throughput and almost half the latency when running up-to 14 VMs.
>
> Can you post patches?

We will publish the code soon but note the patches are for vhost
kernel back-end and not for the qemu user-space back-end.

> Also, I wonder if you have time to do a presentation/discussion session
> so we can get the ball rolling and more people exposed to your approach.
> There is a weekly QEMU Community Call which we can use as the forum.

Sure. I'll send you a separate email to schedule the
presentation/discussion.