Mailing List Archive

-mmultiple *seems* (anecdotally) to make the apps I use run faster. But
then again, I have no real basis for comparison (a 1st rev g3
blue-and-white, and the aforementioned Albook).

Also, adding -fsigned-char may be the default, but I do it anyway just
because. Habit, I guess (I do a lot of gentoo-on-sparc and alpha stuff).

chris.

:: Christopher Gautam Hota
:: Information Technology Specialist
:: MidSOUTH at UALR
:: cghota@midsouth.ualr.edu
:: (501) 683-7339 desk
:: (501) 413-1176 cell

|| Microsoft Certified Systems Engineer
|| Windows XP / Server 2003



David Bélanger wrote:

>On Mon, Feb 21, 2005 at 08:10:17AM -0600, Christopher Hota wrote:
>
>
>>On my new 12" Aluminum PowerBook, I'm using the following with no
>>problems (results in spankin-fast binaries, too):
>>
>>CFLAGS="-O2 -pipe -mcpu=7450 -maltivec -mabi=altivec -mpowerpc-gfxopt
>>-fsigned-char -mstring -mmultiple"
>>CHOST="powerpc-unknown-linux-gnu"
>>CXXFLAGS="${CFLAGS}"
>>MAKEOPTS="-j3"
>>
>>
>>
>
>Hi,
>
>I'm just wondering if the -mmultiple people actually test if -mmultiple
>increases performance on their CPU... because this enables the use of
>load multiple word from my understanding and this instruction might be
>quite expensive depending on the CPU implementation.
>
>-fsigned-char is the not the default?
>
>
>
>David
>
>---
>
>David Bélanger
>Web page: http://www.cs.mcgill.ca/~dbelan2/
>Public key: http://www.cs.mcgill.ca/~dbelan2/public_key.txt
>
>
>--
>gentoo-ppc-user@gentoo.org mailing list
>
>
>

Erik Zeek writes:
|
| You might check out:
| http://gentoo-wiki.com/Safe_Cflags
|
| You could start your own page, and start collecting the data.

Augh! If only this was 'offical' and/or linked into the install docs.
Oh well, color me 'too stupid to find this' :)

|
| >
| > A while ago I was md5sum'ing some iso images and I noticed my G5
| > was _WAY_ slower than my G3 laptop and it was because Id dropped
| > the mcpu=3DG5 setting from my G5 CFLAGS. I realise that md5sum'ing is a
| > special case, but small changes can make a massive change.

Actually, I recompiled our project here on my G5 with the -mcpu=G5
flag and got a *2 in performance, so Im thinking that ppc with no cpu
flag doesnt use most of the cpu features ;) ;).


cheers,
cam

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