From: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
To: Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
Cc: kvm-devel <kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org>
Subject: Re: [PATCH] Lazy FPU save/restore
Date: Sun, 18 Feb 2007 11:39:02 +0200 [thread overview]
Message-ID: <45D81EB6.9010407@qumranet.com> (raw)
In-Reply-To: <45D502A1.5000303-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
Anthony Liguori wrote:
> The following patch saves the host FPU state and loads the guests FPU
> state if !(CR0.MP == 1 && CR0.TS == 1).
>
> When CR0.MP == 1 && CR0.TS == 1, all FPU activity will generate
> exceptions. OS's use these exceptions to implement lazy FPU loading
> to improve context switch time. Since any FPU activity will generate
> traps, we don't have to worry about the guest modifying the host FPU
> state.
>
> My microbenchmark of choice uses FPU operations so I think the results
> are currently tainted. I've only tested on a 32bit SVM system.
>
> Signed-off-by: Anthony Liguori <anthony-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
>
Applied, thanks.
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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next prev parent reply other threads:[~2007-02-18 9:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-16 1:02 [PATCH] Lazy FPU save/restore Anthony Liguori
[not found] ` <45D502A1.5000303-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-02-16 3:23 ` Rusty Russell
2007-02-18 9:39 ` Avi Kivity [this message]
[not found] ` <45D81EB6.9010407-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-18 14:25 ` Avi Kivity
[not found] ` <45D861CD.4020207-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-18 16:13 ` Anthony Liguori
[not found] ` <45D87B22.6070403-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-02-18 16:17 ` Avi Kivity
[not found] ` <45D87C2E.2090806-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-18 18:21 ` Avi Kivity
[not found] ` <45D89917.9090003-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-02-18 22:55 ` Anthony Liguori
[not found] ` <45D8D96B.50104-rdkfGonbjUSkNkDKm+mE6A@public.gmane.org>
2007-02-19 8:13 ` Avi Kivity
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