Re: [discuss] Re: [patch 1/3] x86_64: Node local PDA -- early cpu_to_node

[Ravikiran G Thirumalai <kiran@scalex86.org>]

On Fri, Dec 02, 2005 at 12:43:49PM +0100, Andi Kleen wrote:
> > +#ifdef CONFIG_ACPI_NUMA
> > + 	/*
> > + 	 * Setup cpu_to_node using the SRAT lapcis & ACPI MADT table
> > + 	 * info.
> > + 	 */
> > + 	for (i = 0; i < NR_CPUS; i++)
> > + 		cpu_to_node[i] = apicid_to_node[x86_cpu_to_apicid[i]];
> > +#endif
> 
> This should be in a separate function in srat.c. 

OK,

> 
> And are you sure it will work with k8topology.c. Doesn't look like
> that to me.

I don't have a K8 box yet :(, so I cannot confirm either ways.  
But I thought newer opterons need to use  ACPI_NUMA instead...

<Kconfig quote>
config K8_NUMA
       bool "Old style AMD Opteron NUMA detection"
       depends on NUMA
       default y
       help
         Enable K8 NUMA node topology detection.  You should say Y here if
         you have a multi processor AMD K8 system. This uses an old
         method to read the NUMA configurtion directly from the builtin
         Northbridge of Opteron. It is recommended to use X86_64_ACPI_NUMA
         instead, which also takes priority if both are compiled in.
</quote>

Even if K8 detection is used, cpu_pda will have memory allocated from node0
which is not different from the current state.  So this patch helps Opterons
and EM64t boxes which use ACPI_NUMA, right?  Also the newer opteron boxes
and em64t NUMA boxes can now get node local memory for static per-cpu areas.

Thanks,
Kiran


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