Subject: Re: [PATCH 4/4] kvmppc: convert wrteei to wrtee as kvm guest optimization

From: Arnd Bergmann <[email-masked]>
Date: Tue, 19 Aug 2008 13:42:29 +0200

On Tuesday 19 August 2008, [email-masked] wrote:
> Dependent on the already existing CONFIG_KVM_GUEST config option this patch
> changes wrteei to wrtee allowing the hypervisor to rewrite those to nontrapping
> instructions. Maybe we should split the kvm guest otpimizations in two parts
> one for the overhead free optimizations and on for the rest that might add
> some complexity for non virtualized execution (like this one).
> 
> Signed-off-by: Christian Ehrhardt <[email-masked]>

How significant is the performance impact of this change for non-virtualized
systems? If it's very low, maybe you should not bother with the #ifdef, and
if it's noticable, you might be better off using dynamic patching for this.

	Arnd <><