linux-kernel - Re: i686 quirk for AMD Geode

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Date:	Sun, 8 Nov 2009 20:29:55 +0100 (CET)
From:	Sven-Haegar Koch <haegar@...net.de>
To:	Pavel Machek <pavel@....cz>
cc:	Matteo Croce <technoboy85@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...e.hu>,
	linux-kernel@...r.kernel.org
Subject: Re: i686 quirk for AMD Geode

On Sun, 8 Nov 2009, Pavel Machek wrote:

> On Sun 2009-11-08 18:40:06, Matteo Croce wrote:
> > On Sun, Nov 8, 2009 at 6:37 PM, Pavel Machek <pavel@....cz> wrote:
> > > On Fri 2009-11-06 23:18:06, Matteo Croce wrote:
> > >> On Fri, Nov 6, 2009 at 5:44 PM, H. Peter Anvin <hpa@...or.com> wrote:
> > >> > On 11/06/2009 06:59 AM, Matteo Croce wrote:
> > >> >> indeed it has MMX, MMXEXT and CMOV, just lacks the long NOP instruction (NOPL).
> > >> >
> > >> > MMX and MMXEXT are hardly hallmarks of i686, which leaves only cmov.
> > >> > I'm somewhat wondering about the general value of this patch; is i686
> > >> > code really that much faster on Geode that it's worth it?
> > >> >
> > >> > ? ? ? ?-hpa
> > >> >
> > >> > --
> > >> > H. Peter Anvin, Intel Open Source Technology Center
> > >> > I work for Intel. ?I don't speak on their behalf.
> > >> >
> > >> >
> > >>
> > >> yes, I did some test like gzip, bzip2, lame etc and they give more or less
> > >> the same results of dhrystone
> > >>
> > >> root@...x:/usr/src# CFLAGS='-march=i586' ./dry.c
> > >> Microseconds for one run through Dhrystone:        1.4
> > >> Dhrystones per Second:                          740741
> > > ...
> > >> root@...x:/usr/src# CFLAGS='-march=i686' ./dry.c
> > >> Trying 5000000 runs through Dhrystone:
> > >> Microseconds for one run through Dhrystone:        1.2
> > >> Dhrystones per Second:                          841751
> > >
> > > Teach gcc that geodelx exists? No need to break kernel for that... and
> > > you probably can gain even bigger gains.

But no standard distribution will be made available in a geode special 
version - not enough machines in the marekt. So I think it is better to 
be able to use the i686 specific things they already support, like 
libc6-686 from debian for example.

c'ya
sven

-- 
The lights are fading out, once more...