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Commit 40c07ae8 authored by Pekka Enberg's avatar Pekka Enberg Committed by Linus Torvalds
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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: default avatarPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent a8c0f9a4

include/linux/slab.h

+27 −3
Original line number Original line Diff line number Diff line
@@ -110,7 +110,30 @@ found: 
	return __kmalloc(size, 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.

 * 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);

void kmem_cache_free(struct kmem_cache *c, void *b);

const char *kmem_cache_name(struct kmem_cache *);

const char *kmem_cache_name(struct kmem_cache *);

void *kmalloc(size_t size, gfp_t flags);

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);

void kfree(const void *m);

unsigned int ksize(const void *m);

unsigned int ksize(const void *m);

unsigned int kmem_cache_size(struct kmem_cache *c);

unsigned int kmem_cache_size(struct kmem_cache *c);





static inline void *kcalloc(size_t n, size_t size, gfp_t flags)

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)

#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_ptr_validate(a, b) (0)

#define kmem_cache_alloc_node(c, f, n) kmem_cache_alloc(c, f)

#define kmem_cache_alloc_node(c, f, n) kmem_cache_alloc(c, f)

#define kmalloc_node(s, f, n) kmalloc(s, f)

#define kmalloc_node(s, f, n) kmalloc(s, f)

#define kzalloc(s, f) __kzalloc(s, f)

#define ____kmalloc kmalloc

#define ____kmalloc kmalloc





#endif /* CONFIG_SLOB */

#endif /* CONFIG_SLOB */

mm/util.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -5,18 +5,18 @@ 
#include <asm/uaccess.h>

#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.

 * @size: how many bytes of memory are required.

 * @flags: the type of memory to allocate.

 * @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);

	void *ret = ____kmalloc(size, flags);

	if (ret)

	if (ret)

		memset(ret, 0, size);

		memset(ret, 0, size);

	return ret;

	return ret;

}

}

EXPORT_SYMBOL(kzalloc);

EXPORT_SYMBOL(__kzalloc);





/*

/*

 * kstrdup - allocate space for and copy an existing string

 * kstrdup - allocate space for and copy an existing string