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

From: Alexander Graf
Subject: Re: [Qemu-ppc] [PATCH] ppc: Avoid decrementer related kvm exits
Date: Thu, 20 Oct 2011 10:08:36 -0700

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.


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