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From: "Pavel Dovgalyuk" <dovgaluk@ispras.ru>
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Date: Fri, 12 Jan 2018 15:41:53 +0300
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Subject: Re: [Qemu-devel] [RFC PATCH v3 29/30] replay: improve replay
 performance
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To: 'Paolo Bonzini' <pbonzini@redhat.com>, 'Pavel Dovgalyuk' <Pavel.Dovgaluk@ispras.ru>, qemu-devel@nongnu.org
Cc: kwolf@redhat.com, peter.maydell@linaro.org, boost.lists@gmail.com, quintela@redhat.com, jasowang@redhat.com, mst@redhat.com, zuban32s@gmail.com, maria.klimushenkova@ispras.ru, kraxel@redhat.com, alex.bennee@linaro.org

> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> On 12/01/2018 07:13, Pavel Dovgalyuk wrote:
> >> From: Paolo Bonzini [mailto:pbonzini@redhat.com]
> >> On 11/01/2018 14:12, Pavel Dovgalyuk wrote:
> >>>> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini
> >>>> On 11/01/2018 09:27, Pavel Dovgalyuk wrote:
> >>>>> +        } else {
> >>>>> +            qemu_notify_event();
> >>>>> +        }
> >>>>
> >>>> Before this patch, what would do the qemu_notify_event?
> >>>
> >>> We tried using qemu_notify_event to wake up the iothread and speedup the replay,
> >>> when there is no work for vcpu thread to do.
> >>
> >> But why doesn't the iothread wake up on its own?
> >
> > It will wake up by timeout. But with this change this happens sooner and replay goes faster.
> 
> If you want replays to ignore timeouts, that should be done by ensuring
> that qemu-timer.c passes a zero timeout to main-loop.c.  (It probably
> should be optional, too, maybe via -icount sleep).

Making it optional is a good one.
I'll exclude this patch from the series for working on it later.

Pavel Dovgalyuk