Standardize the constants that describe the smallest and largest
object kept in the kmalloc arrays for SLAB and SLUB.
Differentiate between the maximum size for which a slab cache is used
(KMALLOC_MAX_CACHE_SIZE) and the maximum allocatable size
(KMALLOC_MAX_SIZE, KMALLOC_MAX_ORDER).
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
Index: linux/include/linux/slab.h
===================================================================
--- linux.orig/include/linux/slab.h 2012-09-19 09:21:54.283799310 -0500
+++ linux/include/linux/slab.h 2012-09-19 09:21:58.859894391 -0500
@@ -162,8 +162,9 @@ unsigned int kmem_cache_size(struct kmem
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
#endif
+#ifdef CONFIG_SLAB
/*
- * The largest kmalloc size supported by the slab allocators is
+ * The largest kmalloc size supported by the SLAB allocators is
* 32 megabyte (2^25) or the maximum allocatable page order if that is
* less than 32 MB.
*
@@ -173,9 +174,24 @@ unsigned int kmem_cache_size(struct kmem
*/
#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
(MAX_ORDER + PAGE_SHIFT - 1) : 25)
+#define KMALLOC_SHIFT_MAX KMALLOC_SHIFT_HIGH
+#define KMALLOC_SHIFT_LOW 5
+#else
+/*
+ * SLUB allocates up to order 2 pages directly and otherwise
+ * passes the request to the page allocator.
+ */
+#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
+#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
+#define KMALLOC_SHIFT_LOW 3
+#endif
-#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_HIGH)
-#define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_HIGH - PAGE_SHIFT)
+/* Maximum allocatable size */
+#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_MAX)
+/* Maximum size for which we actually use a slab cache */
+#define KMALLOC_MAX_CACHE_SIZE (1UL << KMALLOC_SHIFT_HIGH)
+/* Maximum order allocatable via the slab allocagtor */
+#define KMALLOC_MAX_ORDER (KMALLOC_SHIFT_MAX - PAGE_SHIFT)
/*
* Kmalloc subsystem.
@@ -184,14 +200,8 @@ unsigned int kmem_cache_size(struct kmem
#if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
#else
-#ifdef CONFIG_SLAB
-#define KMALLOC_MIN_SIZE 32
-#else
-#define KMALLOC_MIN_SIZE 8
+#define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
#endif
-#endif
-
-#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
/*
* Figure out which kmalloc slab an allocation of a certain size
Index: linux/include/linux/slub_def.h
===================================================================
--- linux.orig/include/linux/slub_def.h 2012-09-19 09:21:27.307238804 -0500
+++ linux/include/linux/slub_def.h 2012-09-19 09:21:58.863894464 -0500
@@ -111,19 +111,6 @@ struct kmem_cache {
struct kmem_cache_node *node[MAX_NUMNODES];
};
-/*
- * 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 (2 * PAGE_SIZE)
-
-#define SLUB_PAGE_SHIFT (PAGE_SHIFT + 2)
-
#ifdef CONFIG_ZONE_DMA
#define SLUB_DMA __GFP_DMA
#else
@@ -135,7 +122,7 @@ struct kmem_cache {
* 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[SLUB_PAGE_SHIFT];
+extern struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
/*
* Find the slab cache for a given combination of allocation flags and size.
@@ -204,7 +191,7 @@ static __always_inline void *kmalloc_lar
static __always_inline void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
- if (size > SLUB_MAX_SIZE)
+ if (size > KMALLOC_MAX_CACHE_SIZE)
return kmalloc_large(size, flags);
if (!(flags & SLUB_DMA)) {
@@ -240,7 +227,7 @@ kmem_cache_alloc_node_trace(struct kmem_
static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size) &&
- size <= SLUB_MAX_SIZE && !(flags & SLUB_DMA)) {
+ size <= KMALLOC_MAX_CACHE_SIZE && !(flags & SLUB_DMA)) {
struct kmem_cache *s = kmalloc_slab(size);
if (!s)
Index: linux/mm/slub.c
===================================================================
--- linux.orig/mm/slub.c 2012-09-19 09:21:24.239174845 -0500
+++ linux/mm/slub.c 2012-09-19 09:21:58.863894464 -0500
@@ -2777,7 +2777,7 @@ init_kmem_cache_node(struct kmem_cache_n
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
- SLUB_PAGE_SHIFT * sizeof(struct kmem_cache_cpu));
+ KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
/*
* Must align to double word boundary for the double cmpxchg
@@ -3174,11 +3174,11 @@ int __kmem_cache_shutdown(struct kmem_ca
* Kmalloc subsystem
*******************************************************************/
-struct kmem_cache *kmalloc_caches[SLUB_PAGE_SHIFT];
+struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
EXPORT_SYMBOL(kmalloc_caches);
#ifdef CONFIG_ZONE_DMA
-static struct kmem_cache *kmalloc_dma_caches[SLUB_PAGE_SHIFT];
+static struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
#endif
static int __init setup_slub_min_order(char *str)
@@ -3280,7 +3280,7 @@ void *__kmalloc(size_t size, gfp_t flags
struct kmem_cache *s;
void *ret;
- if (unlikely(size > SLUB_MAX_SIZE))
+ if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return kmalloc_large(size, flags);
s = get_slab(size, flags);
@@ -3316,7 +3316,7 @@ void *__kmalloc_node(size_t size, gfp_t
struct kmem_cache *s;
void *ret;
- if (unlikely(size > SLUB_MAX_SIZE)) {
+ if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
ret = kmalloc_large_node(size, flags, node);
trace_kmalloc_node(_RET_IP_, ret,
@@ -3721,7 +3721,7 @@ void __init kmem_cache_init(void)
caches++;
}
- for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
+ for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
kmalloc_caches[i] = create_kmalloc_cache("kmalloc", 1 << i, 0);
caches++;
}
@@ -3739,7 +3739,7 @@ void __init kmem_cache_init(void)
BUG_ON(!kmalloc_caches[2]->name);
}
- for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
+ for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
char *s = kasprintf(GFP_NOWAIT, "kmalloc-%d", 1 << i);
BUG_ON(!s);
@@ -3751,7 +3751,7 @@ void __init kmem_cache_init(void)
#endif
#ifdef CONFIG_ZONE_DMA
- for (i = 0; i < SLUB_PAGE_SHIFT; i++) {
+ for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[i];
if (s && s->size) {
@@ -3925,7 +3925,7 @@ void *__kmalloc_track_caller(size_t size
struct kmem_cache *s;
void *ret;
- if (unlikely(size > SLUB_MAX_SIZE))
+ if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return kmalloc_large(size, gfpflags);
s = get_slab(size, gfpflags);
@@ -3948,7 +3948,7 @@ void *__kmalloc_node_track_caller(size_t
struct kmem_cache *s;
void *ret;
- if (unlikely(size > SLUB_MAX_SIZE)) {
+ if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
ret = kmalloc_large_node(size, gfpflags, node);
trace_kmalloc_node(caller, ret,
@@ -4307,7 +4307,7 @@ static void resiliency_test(void)
{
u8 *p;
- BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || SLUB_PAGE_SHIFT < 10);
+ BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
printk(KERN_ERR "SLUB resiliency testing\n");
printk(KERN_ERR "-----------------------\n");
--
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