[gentoo-dev] -pentium4 vs -pentium3

[gentoo-dev] -pentium4 vs -pentium3

[Robert Cole]

I recently noted a warning in the new make.conf file to not use the -pentium4 
compiler option and to use -pentium3 instead. My entire system was built from 
stage1 with -pentium4 and I'm not having any issues.

To be safe I switched it to p3 for now. 

Anymore detail on this? Is this something that has to be fixed in gentoo 
specifically or all source in general?

Robert

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[gentoo-dev] -pentium4 vs -pentium3

[Jeff Kowing]

Robert Cole writes:
 > I recently noted a warning in the new make.conf file to not use the -pentium4 
 > compiler option and to use -pentium3 instead. My entire system was built from 
 > stage1 with -pentium4 and I'm not having any issues.
 > 
 > To be safe I switched it to p3 for now. 
 > 
 > Anymore detail on this? Is this something that has to be fixed in gentoo 
 > specifically or all source in general?

Robert, I was bit by at least one of the problems a while back.  It
seems that some of the floating point code is not quite right yet for
pentium4.  I believe this is a gcc and maybe glibc issue.  The
particular example that caused me problems is the glibc modf()
function.  See
http://forums.gentoo.org/viewtopic.php?t=27211&highlight=python+float
for more info and a sample c program that will highlight the problem.

It was suggested at the time by Nick Jones (see
http://article.gmane.org/gmane.linux.gentoo.user/23056) that I back
down to pentium2.  I haven't updated my portage recently, so I
haven't looked at what the new updated make.conf file suggests but I
definitely would follow any advice it gives.

-- 
Jeff Kowing
jeffrey.d.kowing@nasa.gov

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Re: [gentoo-dev] -pentium4 vs -pentium3

[Dhruba Bandopadhyay]

Jeff Kowing said:
> Robert, I was bit by at least one of the problems a while back.  It
> seems that some of the floating point code is not quite right yet for
> pentium4.  I believe this is a gcc and maybe glibc issue.  The
> particular example that caused me problems is the glibc modf()
> function.  See
> http://forums.gentoo.org/viewtopic.php?t=27211&highlight=python+float
> for more info and a sample c program that will highlight the problem.
>
> It was suggested at the time by Nick Jones (see
> http://article.gmane.org/gmane.linux.gentoo.user/23056) that I back
> down to pentium2.  I haven't updated my portage recently, so I
> haven't looked at what the new updated make.conf file suggests but I
> definitely would follow any advice it gives.

I'm also using P4 and have not faced any problems.  Would changing to P3
result in any noticeable drop in performance?  Also, has gcc 3.2.2
compensated for this problem at all in comparison to previous releases?




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RE: [gentoo-dev] -pentium4 vs -pentium3

[Riyad Kalla]

I second these two questions...

-----Original Message-----
From: Dhruba Bandopadhyay [mailto:dhruba@codewordt.co.uk] 
Sent: Sunday, March 02, 2003 7:37 AM
To: gentoo-dev@gentoo.org
Subject: Re: [gentoo-dev] -pentium4 vs -pentium3


Jeff Kowing said:
> Robert, I was bit by at least one of the problems a while back.  It
> seems that some of the floating point code is not quite right yet for
> pentium4.  I believe this is a gcc and maybe glibc issue.  The
> particular example that caused me problems is the glibc modf()
> function.  See
> http://forums.gentoo.org/viewtopic.php?t=27211&highlight=python+float
> for more info and a sample c program that will highlight the problem.
>
> It was suggested at the time by Nick Jones (see
> http://article.gmane.org/gmane.linux.gentoo.user/23056) that I back
> down to pentium2.  I haven't updated my portage recently, so I
> haven't looked at what the new updated make.conf file suggests but I
> definitely would follow any advice it gives.

I'm also using P4 and have not faced any problems.  Would changing to P3
result in any noticeable drop in performance?  Also, has gcc 3.2.2
compensated for this problem at all in comparison to previous releases?




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