Re: [PATCH] [2.4] [2.5] [i386] Add support for GCC 3.1 -march=pentium{-mmx,3,4}

Luigi Genoni
2002-05-25T23:33:19Z

On Sun, 26 May 2002, Dave Jones wrote:

> On Sun, May 26, 2002 at 01:37:39AM +0200, J.A. Magallon wrote:
> > Could you also split
> > Pentium-Pro/Celeron/Pentium-II CONFIG_M686
> > into
> >
> > Pentium-Pro CONFIG_M686
> > Pentium-II/Celeron CONFIG_MPENTIUMII
> >
> > Gcc-3.1 has also a -march=pentium2 specific target, that is not a synomym
> > for any other.
>
> There are also a few extra Athlon targets iirc. athlon-xp and the like,
> which I'm not sure the purpose of. Some gcc know-all want to clue me in
> to what these offer over -march=athlon ?
>
I do not know about the gcc options, but Athlon XP/MP has sse instruction,
while tbird has not, so it could be relate to this.

> > BTW, I think an option to enable -mmmx would also be useful. Nothing more,
> > because afaik sse is only floating point.
>
> Another interesting recently-added option which may be worth
> benchmarking on modern CPUs is the prefetch-loops option.
> In a lot of cases, the kernel 'knows better' and is adding the
> prefetches itself, but it may be interesting to see what difference
> gcc can make here. (More interesting would be examining the output to
> see *where* gcc is putting the prefetches)
>
> Given the immaturity of all these options, I'd doubt they're that good
> an idea for 2.4. Getting them tested during 2.5 may prove to get any
> bugs shaken out in time for $compiler_of_the_choice for 2.6 though.
>
> Dave
>
> --
> | Dave Jones. http://www.codemonkey.org.uk
> | SuSE Labs
> -
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>