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Subject: Re: [Qemu-devel] [regression] dataplane: throughout -40% by commit
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To: Ming Lei <tom.leiming@gmail.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <famz@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Stefan Hajnoczi <stefanha@gmail.com>, qemu-devel <qemu-devel@nongnu.org>, Stefan Hajnoczi <stefanha@redhat.com>


> On Thu, Jul 3, 2014 at 12:23 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> > Il 02/07/2014 18:13, Ming Lei ha scritto:
> >
> >> That must be for generating guest irq, which should have been
> >> processed as batch easily.
> >
> >
> > No, guest irqs are generated (with notify_guest) on every I/O completion
> > even in 2.0.
> 
> In 2.0, only notify_guest() is called after event batch is completed,

Ah, you're right.

> I wrote one patch days ago for fixing the problem, and today
> it is just verified that writes can be decreased to 10K from 120K.

Great.  Can you test/review my aio_notify patch and submit both then?  Bonus
points, but not a requirement IMO,  if it also helps non-dataplane.

This would only leave rt_sigprocmask.

> BTW, what do you think about the patch v4 for submitting I/O as batch?

I was waiting for Kevin to review it.

Paolo