Xeon 5500 series support in kernel

Xeon 5500 series support in kernel

[lchampig]

Xeon 5500 series support in kernel

[xb]

Hi all,

I wonder if there are specific kernel configuration parameters that 
allow to optimize performances on the recent Xeon 5500 processors (aka 
Nehalem).
In particular, should we set CONFIG_GENERIC_CPU or CONFIG_MCORE2 on such 
processors ?
Thanks in advance.
Xavier

Re: Xeon 5500 series support in kernel

[Andi Kleen]

xb <xavier.bru@bull.net> writes:

> I wonder if there are specific kernel configuration parameters that
> allow to optimize performances on the recent Xeon 5500 processors (aka
> Nehalem).

The most important optimization is to use a 64bit kernel with NUMA
support enabled (even if you use 32bit userland)

> In particular, should we set CONFIG_GENERIC_CPU or CONFIG_MCORE2 on
> such processors ?

The kernel doesn't really care about compiler optimizations,
so it shouldn't make any difference. CONFIG_GENERIC_CPU is fine.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.

Re: Xeon 5500 series support in kernel

[Nix]

On 2 Jul 2009, Andi Kleen outgrape:

> xb <xavier.bru@bull.net> writes:
>
>> I wonder if there are specific kernel configuration parameters that
>> allow to optimize performances on the recent Xeon 5500 processors (aka
>> Nehalem).
>
> The most important optimization is to use a 64bit kernel with NUMA
> support enabled (even if you use 32bit userland)

Surely NUMA only benefits you if you have a >1 socket system? Where's
the nonuniform access on a 1-socket machine? Every core is as far from
all the RAM as every other core, isn't it?

Re: Xeon 5500 series support in kernel

[Andi Kleen]

On Sat, Jul 04, 2009 at 12:41:15PM +0100, Nix wrote:
> On 2 Jul 2009, Andi Kleen outgrape:
> 
> > xb <xavier.bru@bull.net> writes:
> >
> >> I wonder if there are specific kernel configuration parameters that
> >> allow to optimize performances on the recent Xeon 5500 processors (aka
> >> Nehalem).
> >
> > The most important optimization is to use a 64bit kernel with NUMA
> > support enabled (even if you use 32bit userland)
> 
> Surely NUMA only benefits you if you have a >1 socket system? Where's

Xeons are typically multi socket. On single socket the overhead
of a NUMA kernel is negligible, so it's best to enable it always.

There are actually some use cases of NUMA kernel code for single
socket too, e.g. it is sometimes used to isolate different 
applications on the VM level.

-Andi

-- 
ak@linux.intel.com -- Speaking for myself only.

RE: Xeon 5500 series support in kernel

[Morten P.D. Stevens]

Hi Andi,

a general question with regard to the new intel nehalem platform:

Which linux version is needed for an intel nehalem based xeon in view of the new intel 5500/5520 chipset drivers?

Does it work with 2.6.18? (Debian Etch)

thanks

--

Morten

Re: Xeon 5500 series support in kernel

[Andi Kleen]

On Sat, Jul 04, 2009 at 08:01:44PM +0200, Morten P.D. Stevens wrote:
> Hi Andi,
> 
> a general question with regard to the new intel nehalem platform:
> 
> Which linux version is needed for an intel nehalem based xeon in view of the new intel 5500/5520 chipset drivers?
> 
> Does it work with 2.6.18? (Debian Etch)

You would need backported drivers for Ethernet etc; the plain
integrated drivers in 2.6.18 will not work. The e1000 project
at sourceforge has driver backports for Ethernet.

I don't know if Debian does regular backports of drivers,
some other distributions with support for old kernels do.

Also some power saving features and performance features 
which are related to power saving (turbo mode) will not work in that old a 
kernel. For full performance it's better to use newer kernels or
kernels with appropiate backports.

-Andi
-- 
ak@linux.intel.com -- Speaking for myself only.