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Date: Sat, 2 Aug 2008 18:26:04 +0100
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Subject: Re: [Qemu-devel] [RFC][PATCH] Add HPET emulation to qemu (v2)
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To: Anthony Liguori <anthony@codemonkey.ws>, qemu-devel@nongnu.org, Beth Kon <eak@us.ibm.com>, Alexander Graf <agraf@suse.de>, kvm@vger.kernel.org

Samuel Thibault, le Sat 02 Aug 2008 18:21:03 +0100, a écrit :
> Anthony Liguori, le Sat 02 Aug 2008 09:46:30 -0500, a écrit :
> > Samuel Thibault wrote:
> > >Beth Kon, le Sat 02 Aug 2008 06:05:14 -0500, a écrit :
> > >  
> > >>I was trying to reproduce the wakeup every 10ms that 
> > >>Samuel Thibault mentioned, thinking the HPET would improve it. 
> > >>But for an idle guest in both cases (with and without HPET), the 
> > >>number of wakeups per second was relatively low (28).
> > >>    
> > >
> > >I was referring to vl.c's timeout = 10; which makes the select call
> > >use a timeout of 10ms. That said, "/* If all cpus are halted then wait
> > >until the next IRQ */", so maybe that's why you get slower wakeups per
> > >second.  I'm still surprised because of the call to qemu_mod_timer in
> > >pit_irq_timer_update which should setup at least a 100Hz timer with
> > >linux guests (when they don't have HPET available).
> > >  
> > 
> > The patch disables that when hpet is active.
> 
> That's why I would expect, indeed, but he is reporting that _without_
         what*
> HPET he gets low wakeups per second already.

Samuel