*BSD News Article 91891


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From: nate@mt.sri.com (Nate Williams)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: FreeBSD and MMX
Date: 24 Mar 1997 19:31:17 GMT
Organization: SRI Intl. - Montana Operations
Lines: 29
Message-ID: <5h6kq5$2se@helena.MT.net>
References: <5h63dn$tq@mitzi.rsmas.miami.edu>
NNTP-Posting-Host: trout.mt.sri.com
X-Newsposter: trn 4.0-test56 (2 Mar 97)
Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:37691

According to Ivan Lima <ivan@nauplius.rsmas.miami.edu>:
>I'm thinking about upgrading my Pentium 75 to Pentium 125 using the
>new Pentium overdrive processor with MMX. Does FreeBSD runs without
>problem in the MMX processors?

I have no personal experience with MMX processors, but since they're
functionality is a super-set of the normal processors they should work
fine (and there are quite a few reports of people happily running FreeBSD
on MMX machines.)

>Does anyone have any information on the
>performace gains in FreeBSD when using MMX?

The performance gain on MMX processors is almost completely due to
doubling the size of the L1 cache on the chip, and little to do with
the new MMX instructions.

In other words, the 'MMX' instructions are worthless in FreeBSD (and
most other multi-tasking OS's), but the double cache is a nice addition that
increases performance.



Nate
-- 
nate@sri.com           | Research Engineer, SRI Intl. - Montana Operations
work #: (406) 457-9000 | 
nate@trout.mt.sri.com  | An unfeatured document is a bug.
home #: (406) 443-7063 |                                - John Polstra