linux-kernel - Re: [PATCH] KVM: don't sent IPI if the vcpu is not online

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Message-Id: <4D59CC65-7577-4F47-869E-80C87E1C28FE@suse.de>
Date:	Mon, 6 Sep 2010 11:19:16 +0200
From:	Alexander Graf <agraf@...e.de>
To:	Avi Kivity <avi@...hat.com>
Cc:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: Re: [PATCH] KVM: don't sent IPI if the vcpu is not online


On 06.09.2010, at 11:14, Avi Kivity wrote:

> On 09/06/2010 12:09 PM, Alexander Graf wrote:
>> 
>>> It can also be running host kernel or user code.
>> In that case it's the same as running guest code, no? We'll pass by the vcpu entry check asap.
> 
> Sure, but the IPI is wasted.  If you spend 10% of your time in host code, you can avoid 10% of the IPIs.
> 
> (actually less, since the atomic part of the guest switch has guest_mode enabled)

Oh. My bad. I had a thinko here :).

Sure, sounds like a good idea.


Alex

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