From: "H. Peter Anvin" <hpa@zytor.com>
To: Avi Kivity <avi@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/4] Really lazy fpu
Date: Wed, 16 Jun 2010 00:32:01 -0700 [thread overview]
Message-ID: <4C187DF1.9030007@zytor.com> (raw)
In-Reply-To: <4C187C22.2080505@redhat.com>
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.
next prev parent reply other threads:[~2010-06-16 7:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-13 15:03 [PATCH 0/4] Really lazy fpu Avi Kivity
2010-06-13 15:03 ` [PATCH 1/4] x86, fpu: merge __save_init_fpu() implementations Avi Kivity
2010-06-13 15:03 ` [PATCH 2/4] x86, fpu: run device not available trap with interrupts enabled Avi Kivity
2010-06-13 15:03 ` [PATCH 3/4] x86, fpu: Let the fpu remember which cpu it is active on Avi Kivity
2010-06-13 15:03 ` [PATCH 4/4] x86, fpu: don't save fpu state when switching from a task Avi Kivity
2010-06-13 20:45 ` [PATCH 0/4] Really lazy fpu Valdis.Kletnieks
2010-06-14 7:47 ` Avi Kivity
2010-06-16 7:24 ` Avi Kivity
2010-06-16 7:32 ` H. Peter Anvin [this message]
2010-06-16 8:02 ` Avi Kivity
2010-06-16 8:39 ` Ingo Molnar
2010-06-16 9:01 ` Samuel Thibault
2010-06-16 9:43 ` Avi Kivity
2010-06-16 9:10 ` Nick Piggin
2010-06-16 9:30 ` Avi Kivity
2010-06-16 9:28 ` Avi Kivity
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