Re: nr_cpu_ids incorrect on AMD Quad-Core Opteron 8380

[zhiyi]

On 2/02/2010, at 4:04 AM, Borislav Petkov wrote:

> On Mon, Feb 1, 2010 at 2:57 PM, Borislav Petkov <petkovbb@xxxxxxxxxxxxxx 
> > wrote:
> > On Sun, Jan 31, 2010 at 11:59 PM, zhiyi <zhuang@xxxxxxxxxxxxxx>  
> > wrote:
> > > My module worked for a kernel 2.6.29 with CONFIG_NR_CPUS=64 on my  
> > > dual
> > > quad-core AMD Opteron. The value of nr_cpu_ids I got from the same  
> > > module
> > > was correct (8).
> >
> > This could mean that your include/generated/autoconf.h, which is  
> > used by
> > external modules, is not updated and contains CONFIG_NR_CPUS=8. Do
> >
> > make mrproper
> >
> > in your kernel directory by moving your .config out of the way  
> > first and
> > then rebuild your kernel and external module(s). nr_cpu_ids should  
> > pick
> > up the updated CONFIG_NR_CPUS value from your .config.
>
> That's actually not necessary - the nr_cpu_ids thing is set at compile
> time to CONFIG_NR_CPUS but then capped to a possibly lower value upon
> boot depending on the info in the ACPI mptables. Can you please send  
> the
> .config and the full dmesg of the quadsocket machine?

The dmesg relevant to nr_cpu_ids of the quad socket is:

[    0.000000] NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:32 nr_node_ids:4

For comparison purposes, the dmesg for the dual socket is:

[    0.000000] NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:8 nr_node_ids:1

It seems nr_node_ids:1 for the dual socket is not quite right though.

Cheers,
Zhiyi




> Thanks.
>
> --
> Regards/Gruss,
> Boris

=======================
Zhiyi Huang
Dept of Computer Science
University of Otago
Email: hzy@xxxxxxxxxxxxxx
Phone: 0064-3-4795680
Fax: 0064-3-4798529

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