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Date: Tue, 16 Jan 2007 15:34:31 -0800
From: "Kip Macy" <kip.macy@gmail.com>
To: "Ivan Voras" <ivoras@fer.hr>
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Cc: freebsd-current@freebsd.org, freebsd-arch@freebsd.org
Subject: Re: [PATCH] Mantaining turnstile aligned to 128 bytes in i386 CPUs
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> Maybe even someone finds a way to get optimized versions of memcpy in
> the kernel :)
>
> I was thinking: AFAIK the only major stopper is context saving of the
> various "auxiliary" registers - FPU, MMX, SSE, right? But is it an
> all-or-nothing situation? I.e. does it make sense (can it be done?) to
> just elect to save the MMX context? (AFAIK they are different registers
> than SSE, but overlay FPU registers?) The idea is to save something
> smaller than the full set.

It makes a huge difference in a proprietary file serving appliance
that I know of. However, past measurements on FreeBSD have supposedly
indicated that it isn't that big win as a result of increased context
switch time.

     -Kip