Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8da3430d8a7f885c2bf65121181d76c9d290a86e
Commit:     8da3430d8a7f885c2bf65121181d76c9d290a86e
Parent:     6310984694c8204ad16a2414cd58808fae68e02b
Author:     Eric Dumazet <[EMAIL PROTECTED]>
AuthorDate: Sun May 6 14:49:29 2007 -0700
Committer:  Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Mon May 7 12:12:53 2007 -0700

    slab: NUMA kmem_cache diet
    
    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 <[EMAIL PROTECTED]>
    Cc: Pekka Enberg <[EMAIL PROTECTED]>
    Cc: Andy Whitcroft <[EMAIL PROTECTED]>
    Cc: Christoph Lameter <[EMAIL PROTECTED]>
    Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
    Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
 mm/slab.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index 00f98b9..1f2627c 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];
 
        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 =
-
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