Re: Poor performance of G5 on GNOME's CPU benchmarks.
On Tue, 2008-08-05 at 23:17 +0900, Charles Plessy wrote:
> Le Mon, Aug 04, 2008 at 11:10:02AM +0200, Michel Dänzer a écrit :
> > On Mon, 2008-08-04 at 10:24 +0900, Charles Plessy wrote:
> > > http://gcc.gnu.org/onlinedocs/gcc/PowerPC-AltiVec-Built_002din-Functions.html
> > These flags are prerequisites for allowing the resulting binaries to
> > contain Altivec code at all, but on their own they don't cause any such
> > code to be generated (except maybe for some simple cases like memory
> > copies). Current versions of GCC can automatically vectorize some code
> > with -ftree-vectorize, but the results probably still can't compete with
> > hand-optimized code.
> > Also note that these flags will make the resulting binaries unusable on
> > systems without Altivec support.
> Well, it seems that it makes it doubly impossible to get the best
> performance out of those machines :(
Why? There's quite a few packages in Debian that will use Altivec when
available but still work otherwise. You just have to be careful not to
use any of the above flags for the generic code.
> Another example I have is a map website by Yahoo Japan:
> With Iceweasel it is slow on G5 and fluid on Intel.
With the same graphics card and drivers?
Earthling Michel Dänzer | http://tungstengraphics.com
Libre software enthusiast | Debian, X and DRI developer