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CFLAGS and kernel configuration for specific CPUs?

 
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Wim Cossement
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Since: Mar 21, 2007
Posts: 20



PostPosted: Tue May 08, 2007 4:49 pm    Post subject: CFLAGS and kernel configuration for specific CPUs?
Archived from groups: alt>os>linux>gentoo (more info?)

Hi,

I'd like some advice about the best configuration of my CFLAGS in
/etc/make.conf, as wel as to know what the kernel config should be set
to to maximise performance.

There is one laptop, a Dell Inspiron 9400 with a Centrino Duo CPU.
According to the Gentoo newsgroups and some other sites I found out that
this is in fact a Core2 Duo CPU (T7200), and /proc/cpuinfo confirms
this. There is also suggested if you have the 'pni' and 'lm' flags you
march should be nocona.

So this leaves me with this:
CFLAGS="-march=nocona -O3 -pipe -fomit-frame-pointer" // all good?
CHOST="i686-pc-linux-gnu"
CXXFLAGS="${CFLAGS}"
MAKEOPTS="-j3" // shouldn't this be j5 since it's a Duo CPU?
LDFLAGS="-Wl,-O1" // fine too?

How about 'Processor type and features' in the kernel config?

SPM on or off?
Processor family on Pentium Pro, M or 4?
SMT on or off?
Multi core scheduler on or off?

And last but not least, are there any specific USE flags that should or
shoudn't be set?

And there is also a desktop with a Core2 Duo (6600), what should I do there?

Here I'm using linux-2.6.20-gentoo-r6 sources, so there I have the Core
2 CPU option, but the laptop is still on linux-2.6.18-suspend2-r1 so
there it's not available (yet?).

Thanks,

Wimmy
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FraterM
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Since: May 10, 2007
Posts: 1



PostPosted: Thu May 10, 2007 6:49 pm    Post subject: Re: CFLAGS and kernel configuration for specific CPUs? [Login to view extended thread Info.]
Archived from groups: per prev. post (more info?)

According to http://gentoo-wiki.com/Safe_Cflags#Intel_Core_2_Duo.2FQuad_.2F_Xeon_51xx.2F53xx

Intel Core 2 Duo/Quad / Xeon 51xx/53xx

32 bit profile (x86)

CHOST="i686-pc-linux-gnu"
CFLAGS="-march=prescott -O2 -pipe -fomit-frame-pointer"
CXXFLAGS="${CFLAGS}"

64 bit profile (amd64)

CHOST="x86_64-pc-linux-gnu"
CFLAGS="-march=nocona -O2 -pipe"
CXXFLAGS="${CFLAGS}"

As far as number of make jobs goes, I couldn't say.

On May 8, 5:49 am, Wim Cossement wrote:
> Hi,
>
> I'd like some advice about the best configuration of my CFLAGS in
> /etc/make.conf, as wel as to know what the kernel config should be set
> to to maximise performance.
>
> There is one laptop, a Dell Inspiron 9400 with a Centrino Duo CPU.
> According to the Gentoo newsgroups and some other sites I found out that
> this is in fact a Core2 Duo CPU (T7200), and /proc/cpuinfo confirms
> this. There is also suggested if you have the 'pni' and 'lm' flags you
> march should be nocona.
>
> So this leaves me with this:
> CFLAGS="-march=nocona -O3 -pipe -fomit-frame-pointer" // all good?
> CHOST="i686-pc-linux-gnu"
> CXXFLAGS="${CFLAGS}"
> MAKEOPTS="-j3" // shouldn't this be j5 since it's a Duo CPU?
> LDFLAGS="-Wl,-O1" // fine too?
>
> How about 'Processor type and features' in the kernel config?
>
> SPM on or off?
> Processor family on Pentium Pro, M or 4?
> SMT on or off?
> Multi core scheduler on or off?
>
> And last but not least, are there any specific USE flags that should or
> shoudn't be set?
>
> And there is also a desktop with a Core2 Duo (6600), what should I do there?
>
> Here I'm using linux-2.6.20-gentoo-r6 sources, so there I have the Core
> 2 CPU option, but the laptop is still on linux-2.6.18-suspend2-r1 so
> there it's not available (yet?).
>
> Thanks,
>
> Wimmy
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