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slab: NUMA kmem_cache diet

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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()

cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
                                 nr_node_ids * sizeof(struct kmem_list3 *);

On my two nodes x86_64 machine, kmem_cache.obj_size is now 192 instead of 704
(This is because on x86_64, MAX_NUMNODES is 64)

On bigger NUMA setups, this might reduce the gfporder of "cache_cache"

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Dumazet 2007-05-06 14:49:29 -07:00 committed by Linus Torvalds
parent 6310984694
commit 8da3430d8a
1 changed files with 20 additions and 4 deletions
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24
mm/slab.c
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@ -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];
unsigned int flags; /* constant flags */
unsigned int num; /* # of objs per slab */
@ -444,6 +443,17 @@ struct kmem_cache {
int obj_offset;
int obj_size;
#endif
/*
* We put nodelists[] at the end of kmem_cache, because we want to size
* this array to nr_node_ids slots instead of MAX_NUMNODES
* (see kmem_cache_init())
* We still use [MAX_NUMNODES] and not [1] or [0] because cache_cache
* is statically defined, so we reserve the max number of nodes.
*/
struct kmem_list3 *nodelists[MAX_NUMNODES];
/*
* Do not add fields after nodelists[]
*/
};
#define CFLGS_OFF_SLAB (0x80000000UL)
@ -678,9 +688,6 @@ static struct kmem_cache cache_cache = {
.shared = 1,
.buffer_size = sizeof(struct kmem_cache),
.name = "kmem_cache",
#if DEBUG
.obj_size = sizeof(struct kmem_cache),
#endif
};
#define BAD_ALIEN_MAGIC 0x01020304ul
@ -1440,6 +1447,15 @@ void __init kmem_cache_init(void)
cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE];
/*
* struct kmem_cache size depends on nr_node_ids, which
* can be less than MAX_NUMNODES.
*/
cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
nr_node_ids * sizeof(struct kmem_list3 *);
#if DEBUG
cache_cache.obj_size = cache_cache.buffer_size;
#endif
cache_cache.buffer_size = ALIGN(cache_cache.buffer_size,
cache_line_size());
cache_cache.reciprocal_buffer_size =