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Re: [Qemu-ppc] [PATCH] ppc: Avoid decrementer related kvm exits

From: David Gibson
Subject: Re: [Qemu-ppc] [PATCH] ppc: Avoid decrementer related kvm exits
Date: Fri, 21 Oct 2011 12:13:29 +1100
User-agent: Mutt/1.5.21 (2010-09-15)

On Thu, Oct 20, 2011 at 10:08:36AM -0700, Alexander Graf wrote:
> On 16.10.2011, at 22:26, David Gibson wrote:
> > In __cpu_ppc_store_decr(), we set up a regular timer used to trigger
> > decrementer interrupts.  This is necessary to implement the decrementer
> > properly under TCG, but is unnecessary under KVM (true for both Book3S-PR
> > and Book3S-HV KVM variants), because the kernel handles generating and
> > delivering decrementer exceptions.
> > 
> > Under kvm, in fact, the timer causes expensive and unnecessary exits from
> > kvm to qemu.  This patch, therefore, disables setting the timer when kvm
> > is in use.
> > 
> > Signed-off-by: Anton Blanchard <address@hidden>
> > Signed-off-by: David Gibson <address@hidden>
> Thanks, applied to ppc-next.

I think you've forgotten to push out the new ppc-next again..

David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!

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