linux-kernel - Re: [PATCH 0/4] Really lazy fpu

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Message-ID: <4C187DF1.9030007@zytor.com>
Date:	Wed, 16 Jun 2010 00:32:01 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Ingo Molnar <mingo@...e.hu>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/4] Really lazy fpu

On 06/16/2010 12:24 AM, Avi Kivity wrote:
> 
> Ingo, Peter, any feedback on this?
> 

Conceptually, this makes sense to me.  However, I have a concern what
happens when a task is scheduled on another CPU, while its FPU state is
still in registers in the original CPU.  That would seem to require
expensive IPIs to spill the state in order for the rescheduling to
proceed, and this could really damage performance.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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