Messages in this thread |  | | | Date | Wed, 16 Mar 2005 20:09:18 +0100 | | From | Manfred Spraul <> | | Subject | Re: Fw: [PATCH] NUMA Slab Allocator |
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Martin J. Bligh wrote:
>That'd be my inclination .... but OTOH, we do that for pagecache OK. > The page cache doesn't have a global hash table.
> Dunno, >I'm torn. Depends if there's locality on the file access or not, I guess. >Is there any *harm* in doing it node local .... perhaps creating a node >mem pressure imbalance (OTOH, there's loads of stuff that does that anyway ;-)) > > > The harm is slower kmem_cache_free and a lower hit ratio for the per-cpu caches: kmem_cache_free must identify and return wrong node objects, and due to these returns, the per-cpu array is more often empty in kmem_cache_alloc.
IIRC someone from SGI wrote that they have seen bad performance in fork-bomb tests on large cpu count systems which might be caused by inter-node traffic on the mm_struct structure and that they think that a numa aware allocator would help. As far as I know no tests were done to very that assumption.
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