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Date: Mon, 8 May 2006 13:27:21 +0200
From: Alexander Leidinger <Alexander@Leidinger.net>
To: freebsd-current@freebsd.org, des@des.no
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Subject: Re: I_686  MMX / 3DNOW / SSE / SSE2 ?
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Quoting des@des.no (Dag-Erling Smørgrav) (Mon, 08 May 2006 05:13:00 +0200):

> We don't want to use floating point within the kernel, for a variety
> of reasons (one of them being that saving and restoring the floating
> point context when switching in and out of the kernel is very
> expensive).

FYI...

The patches which port the revamped FPU handling from DFly don't have
this expensive behavior for every switch. AFAIR only when the kernel
used the FPU some context is saved. It also allows to use SIMD
instructions in the kernel (this may be beneficial in some places).

Bye,
Alexander.

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