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authorChristoph Lameter <cl@linux-foundation.org>2009-02-17 12:05:07 -0500
committerPekka Enberg <penberg@cs.helsinki.fi>2009-02-20 12:28:36 +0200
commitfe1200b63d158b28eef6d4de1e5b5f99c681ba2f (patch)
treebff176ef50efbc161e240ec4295a6da815eae997 /include/linux/slub_def.h
parentb578f3fcca1e78624dfb5f358776e63711d7fda2 (diff)
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SLUB: Introduce and use SLUB_MAX_SIZE and SLUB_PAGE_SHIFT constants
As a preparational patch to bump up page allocator pass-through threshold, introduce two new constants SLUB_MAX_SIZE and SLUB_PAGE_SHIFT and convert mm/slub.c to use them. Reported-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Tested-by: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com> Signed-off-by: Christoph Lameter <cl@linux-foundation.org> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Diffstat (limited to 'include/linux/slub_def.h')
-rw-r--r--include/linux/slub_def.h19
1 files changed, 16 insertions, 3 deletions
diff --git a/include/linux/slub_def.h b/include/linux/slub_def.h
index 2f5c16b1aacd..986e09dcfd8f 100644
--- a/include/linux/slub_def.h
+++ b/include/linux/slub_def.h
@@ -121,10 +121,23 @@ struct kmem_cache {
#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
/*
+ * Maximum kmalloc object size handled by SLUB. Larger object allocations
+ * are passed through to the page allocator. The page allocator "fastpath"
+ * is relatively slow so we need this value sufficiently high so that
+ * performance critical objects are allocated through the SLUB fastpath.
+ *
+ * This should be dropped to PAGE_SIZE / 2 once the page allocator
+ * "fastpath" becomes competitive with the slab allocator fastpaths.
+ */
+#define SLUB_MAX_SIZE (PAGE_SIZE)
+
+#define SLUB_PAGE_SHIFT (PAGE_SHIFT + 1)
+
+/*
* We keep the general caches in an array of slab caches that are used for
* 2^x bytes of allocations.
*/
-extern struct kmem_cache kmalloc_caches[PAGE_SHIFT + 1];
+extern struct kmem_cache kmalloc_caches[SLUB_PAGE_SHIFT];
/*
* Sorry that the following has to be that ugly but some versions of GCC
@@ -212,7 +225,7 @@ static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
static __always_inline void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
- if (size > PAGE_SIZE)
+ if (size > SLUB_MAX_SIZE)
return kmalloc_large(size, flags);
if (!(flags & SLUB_DMA)) {
@@ -234,7 +247,7 @@ void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size) &&
- size <= PAGE_SIZE && !(flags & SLUB_DMA)) {
+ size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) {
struct kmem_cache *s = kmalloc_slab(size);
if (!s)