Re: [PATCH] slab: NUMA kmem_cache diet

[Pekka J Enberg <penberg@cs.helsinki.fi>]

(Please inline patches to the mail, makes it easier to review.)

On Thu, 22 Mar 2007, Eric Dumazet wrote:
> Some NUMA machines have a big MAX_NUMNODES (possibly 1024), but fewer possible
> nodes. This patch dynamically sizes the 'struct kmem_cache' to allocate only
> needed space.
> 
> I moved nodelists[] field at the end of struct kmem_cache, and use the
> following computation in kmem_cache_init()

Hmm, what seems bit worrying is:

diff --git a/mm/slab.c b/mm/slab.c
index abf46ae..b187618 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -389,7 +389,6 @@ struct kmem_cache {
        unsigned int buffer_size;
        u32 reciprocal_buffer_size;
 /* 3) touched by every alloc & free from the backend */
-       struct kmem_list3 *nodelists[MAX_NUMNODES];

I think nodelists is placed at the beginning of the struct for a reason. 
But I have no idea if it actually makes any difference...

			Pekka