Re: [NUMA , x86_64] Why memnode_shift is chosen with the lowest possible value ?

[Andi Kleen]

> Using memnode_shift=33 would access only 2 bytes from this memnodemap[], 
> touching fewer cache lines (well , one cache line). kfree() and friends 
> would be slightly faster, at least cache friendly.

Agreed. Please send a patch.

> 
> Another question is :
> 
> Could we add in pda (struct x8664_pda) the node of the cpu ?
> 
> We currently do :
> 
> #define numa_node_id()             (cpu_to_node(raw_smp_processor_id()))
> 
> Instead of reading the processor_id from pda, then access cpu_to_node[], we 
> could directly get this information from pda.
> 
> #if defined(CONFIG_NUMA)
> static inline __attribute_pure__ int numa_node_id() { return 
> read_pda(node);}
> #else
> #define numa_node_id()             0
> #endif

Should be fine too. Please send a patch for that too.

-Andi

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