Gentoo Archives: gentoo-user

From: Tom Smith <tom71713-gentoo52478932@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] USE flags: mmx sse sse2
Date: Fri, 13 Jan 2006 02:49:12
Message-Id: 43C71442.5050100@yahoo.com
In Reply to: Re: [gentoo-user] USE flags: mmx sse sse2 by Raphael Melo de Oliveira Bastos Sales
1 Well, if they're /not/ mutually exclusive, another question that comes
2 up is...
3
4 If a program is compiled with sse or sse2 support on a Pentium II, will
5 the program run slower than it otherwise would? (Some of the programs I
6 have are compiled and then distributed to servers with different
7 CPUs--P-IIs and P-IVs, mainly.)
8
9 Raphael Melo de Oliveira Bastos Sales wrote:
10
11 >Certain program have support for either of these extentions. The
12 >program will most likely use the best one for the job.
13 >
14 >They can be mutually exclusive, however, if you use the CFLAG
15 >-mfpmath=sse,387. As far as I know it, it will try to use SSE
16 >instructions for math where possible, in detriment of using the 387
17 >math co-processor. But this only get any advantage when using AMD64
18 >processors.
19 >
20 >I never tested it, I just copied what the Gentoo Wiki says about it. ;P
21 >
22 >2006/1/12, Willie Wong <wwong@×××××××××.edu>:
23 >
24 >
25 >>On Thu, Jan 12, 2006 at 03:09:40PM -0700, Penguin Lover Tom Smith squawked:
26 >>
27 >>
28 >>>Are these flags mutually exclusive?
29 >>>
30 >>>I know, for example, that if I have a Pentium II that the MMX flag
31 >>>should apply while the sse and sse2 flags would not.
32 >>>
33 >>>But what if I have a Pentium III or IV? Would I only use the most recent
34 >>>"optimization" or do I need to add all three to take advantage of each one?
35 >>>
36 >>>I checked the USE flag descriptions and there wasn't anything indicating
37 >>>indicating whether the can or should be used together.
38 >>>
39 >>>
40 >>>
41 >>Not quite sure how it works officially. But I run a Pentium IV, and I
42 >>have mmx mmxext sse sse2 enabled, so they are at least NOT mutually
43 >>exclusive.
44 >>
45 >>W
46 >>--
47 >>All science is either physics or stamp collecting.
48 >> ~Ernest Rutherford
49 >>Sortir en Pantoufles: up 61 days, 15:40
50 >>--
51 >>gentoo-user@g.o mailing list
52 >>
53 >>
54 >>
55 >>
56 >
57 >
58 >
59 --
60 gentoo-user@g.o mailing list

Replies

Subject Author
Re: [gentoo-user] USE flags: mmx sse sse2 John Myers <electronerd@×××××××××××××.net>
Re: [gentoo-user] USE flags: mmx sse sse2 Francesco Riosa <BastianBalthazarBux@×××××××××.it>