[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>
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 1216b09..15e1d97 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -110,7 +110,30 @@
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_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 @@
#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 */