Date: Sun, 8 Nov 2009 18:37:08 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Matteo Croce <technoboy85@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@elte.hu>,
       linux-kernel@vger.kernel.org
Subject: Re: i686 quirk for AMD Geode
Message-ID: <20091108173708.GF1372@ucw.cz>
References: <40101cc30910021912r17b3a08bue1b9412e4fa47d89@mail.gmail.com> <20091003072127.GC21407@elte.hu> <40101cc30911060659k7b3b6428ob1340e476bdbac5b@mail.gmail.com> <4AF4526B.4060101@zytor.com> <40101cc30911061418w357b74d8i3bf9a9537de052d4@mail.gmail.com>
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On Fri 2009-11-06 23:18:06, Matteo Croce wrote:
> On Fri, Nov 6, 2009 at 5:44 PM, H. Peter Anvin <hpa@zytor.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@alix:/usr/src# CFLAGS='-march=i586' ./dry.c
> Microseconds for one run through Dhrystone:        1.4
> Dhrystones per Second:                          740741
...
> root@alix:/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.
									Pavel

-- 
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