Re: NUMA aware slab allocator V3

Martin J. Bligh
2005-05-16T21:26:02Z

> Right, the SGI boxes have discontiguous memory within a node, but it's
> not represented by pgdats (like you said, one 'virtual memmap' spans
> the whole address space of a node). Sparse can help simplify this
> across platforms, but has the potential to be more expensive for
> systems with dynamically sized holes, due to the additional calculation
> and potential cache miss associated with indexing into the correct
> memmap (Dave can probably correct me here, it's been awhile). With a
> virtual memmap, you only occasionally take a TLB miss on the struct
> page access after indexing into the array.

That's exactly what was brilliant about Andy's code ... it fixed that,
there shouldn't be extra references ...

>> transition config options are a bit of a mess ... Andy, I presume
>> CONFIG_NEED_MULTIPLE_NODES is really CONFIG_NEED_MULTIPLE_PGDATS ?
>
> Yeah, makes sense for the NUMA aware slab allocator to depend on
> CONFIG_NUMA.

Andy confirmed offline that this is really CONFIG_NEED_MULTIPLE_PGDATS,
and is just named wrong.

M.