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authorDave Hansen <dave.hansen@linux.intel.com>2014-01-28 14:24:50 -0800
committerPekka Enberg <penberg@kernel.org>2014-01-31 13:40:34 +0200
commit433a91ff5fa19e3eb70b12f7056f234aebd09ac2 (patch)
tree9d0af35284088374a2a203cde24c4a7360d7abec /include/linux/slab.h
parent26e4f2057516f1c457e0e95346a00303f983ad53 (diff)
mm: sl[uo]b: fix misleading comments
On x86, SLUB creates and handles <=8192-byte allocations internally. It passes larger ones up to the allocator. Saying "up to order 2" is, at best, ambiguous. Is that order-1? Or (order-2 bytes)? Make it more clear. SLOB commits a similar sin. It *handles* page-size requests, but the comment says that it passes up "all page size and larger requests". SLOB also swaps around the order of the very-similarly-named KMALLOC_SHIFT_HIGH and KMALLOC_SHIFT_MAX #defines. Make it consistent with the order of the other two allocators. Cc: Matt Mackall <mpm@selenic.com> Cc: Andrew Morton <akpm@linux-foundation.org> Acked-by: Christoph Lameter <cl@linux-foundation.org> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
Diffstat (limited to 'include/linux/slab.h')
-rw-r--r--include/linux/slab.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 1e2f4fe12773..f76e956b4011 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -205,8 +205,8 @@ struct kmem_cache {
#ifdef CONFIG_SLUB
/*
- * SLUB allocates up to order 2 pages directly and otherwise
- * passes the request to the page allocator.
+ * SLUB directly allocates requests fitting in to an order-1 page
+ * (PAGE_SIZE*2). Larger requests are passed to the page allocator.
*/
#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
@@ -217,12 +217,12 @@ struct kmem_cache {
#ifdef CONFIG_SLOB
/*
- * SLOB passes all page size and larger requests to the page allocator.
+ * SLOB passes all requests larger than one page to the page allocator.
* No kmalloc array is necessary since objects of different sizes can
* be allocated from the same page.
*/
-#define KMALLOC_SHIFT_MAX 30
#define KMALLOC_SHIFT_HIGH PAGE_SHIFT
+#define KMALLOC_SHIFT_MAX 30
#ifndef KMALLOC_SHIFT_LOW
#define KMALLOC_SHIFT_LOW 3
#endif