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[PATCH] slab: optimize constant-size kzalloc calls 

As suggested by Eric Dumazet, optimize kzalloc() calls that pass a
compile-time constant size.  Please note that the patch increases kernel
text slightly (~200 bytes for defconfig on x86).

Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Pekka Enberg 2006-03-25 03:06:43 -08:00 committed by Linus Torvalds
parent a8c0f9a41f
commit 40c07ae8da
2 changed files with 30 additions and 6 deletions
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30
include/linux/slab.h
View File

@ -110,7 +110,30 @@ static inline void *kmalloc(size_t size, gfp_t flags)
return __kmalloc(size, flags);
}
extern void *kzalloc(size_t, gfp_t);
extern void *__kzalloc(size_t, gfp_t);
static inline void *kzalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
int i = 0;
#define CACHE(x) \
if (size <= x) \
goto found; \
else \
i++;
#include "kmalloc_sizes.h"
#undef CACHE
{
extern void __you_cannot_kzalloc_that_much(void);
__you_cannot_kzalloc_that_much();
}
found:
return kmem_cache_zalloc((flags & GFP_DMA) ?
malloc_sizes[i].cs_dmacachep :
malloc_sizes[i].cs_cachep, flags);
}
return __kzalloc(size, flags);
}
/**
* kcalloc - allocate memory for an array. The memory is set to zero.
@ -161,14 +184,14 @@ void *kmem_cache_zalloc(struct kmem_cache *, gfp_t);
void kmem_cache_free(struct kmem_cache *c, void *b);
const char *kmem_cache_name(struct kmem_cache *);
void *kmalloc(size_t size, gfp_t flags);
void *kzalloc(size_t size, gfp_t flags);
void *__kzalloc(size_t size, gfp_t flags);
void kfree(const void *m);
unsigned int ksize(const void *m);
unsigned int kmem_cache_size(struct kmem_cache *c);
static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
{
return kzalloc(n * size, flags);
return __kzalloc(n * size, flags);
}
#define kmem_cache_shrink(d) (0)
@ -176,6 +199,7 @@ static inline void *kcalloc(size_t n, size_t size, gfp_t flags)
#define kmem_ptr_validate(a, b) (0)
#define kmem_cache_alloc_node(c, f, n) kmem_cache_alloc(c, f)
#define kmalloc_node(s, f, n) kmalloc(s, f)
#define kzalloc(s, f) __kzalloc(s, f)
#define ____kmalloc kmalloc
#endif /* CONFIG_SLOB */

6
mm/util.c
View File

@ -5,18 +5,18 @@
#include <asm/uaccess.h>
/**
* kzalloc - allocate memory. The memory is set to zero.
* __kzalloc - allocate memory. The memory is set to zero.
* @size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*/
void *kzalloc(size_t size, gfp_t flags)
void *__kzalloc(size_t size, gfp_t flags)
{
void *ret = ____kmalloc(size, flags);
if (ret)
memset(ret, 0, size);
return ret;
}
EXPORT_SYMBOL(kzalloc);
EXPORT_SYMBOL(__kzalloc);
/*
* kstrdup - allocate space for and copy an existing string