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mm: faster kmalloc_array(), kcalloc()

PATCH Applied Alexey Dobriyan 1 participant 1 message Jun 27, 2016 Slab allocator

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PATCH 1/1 mm: faster kmalloc_array(), kcalloc()

When both arguments to kmalloc_array() or kcalloc() are known at compile time then their product is known at compile time but search for kmalloc cache happens at runtime not at compile time.

---

 include/linux/slab.h |    2 ++
 1 file changed, 2 insertions(+)
include/linux/slab.h +2 -0
@@ -565,6 +565,8 @@ static inline void *kmalloc_array(size_t n, size_t size, gfp_t flags)
 {
 	if (size != 0 && n > SIZE_MAX / size)
 		return NULL;
+	if (__builtin_constant_p(n) && __builtin_constant_p(size))
+		return kmalloc(n * size, flags);
 	return __kmalloc(n * size, flags);
 }