[PATCH] mm/slab.c: prefetchw the start of new allocated objects

Mostobjects returned by __cache_alloc() will be written by the caller,
(but not all callers want to write all the object, but just at the
begining) prefetchw() tells the modern CPU to think about the future
writes, ie start some memory transactions in advance.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/slab.c b/mm/slab.c
index 59d382f..75127a6 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2166,7 +2166,9 @@ static inline void *__cache_alloc(kmem_cache_t *cachep, unsigned int __nocast fl
                objp = cache_alloc_refill(cachep, flags);
        }
        local_irq_restore(save_flags);
-       objp = cache_alloc_debugcheck_after(cachep, flags, objp, __builtin_return_address(0));
+       objp = cache_alloc_debugcheck_after(cachep, flags, objp,
+                                       __builtin_return_address(0));
+       prefetchw(objp);
        return objp;
 }