perf bench: Fix order of arguments to memcpy_alloc_mem

This was causing the destination instead of the source to be filled.  As
a result, the source was typically all mapped to one zero page, and
hence very cacheable.
Signed-off-by: Bruce Merry <bmerry@ska.ac.za>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20150115092022.GA11292@krytonSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/bench/mem-memcpy.c

@@ -289,7 +289,7 @@ static u64 do_memcpy_cycle(const struct routine *r, size_t len, bool prefault)
 	memcpy_t fn = r->fn.memcpy;
 	int i;
 
-	memcpy_alloc_mem(&src, &dst, len);
+	memcpy_alloc_mem(&dst, &src, len);
 
 	if (prefault)
 		fn(dst, src, len);
@@ -312,7 +312,7 @@ static double do_memcpy_gettimeofday(const struct routine *r, size_t len,
 	void *src = NULL, *dst = NULL;
 	int i;
 
-	memcpy_alloc_mem(&src, &dst, len);
+	memcpy_alloc_mem(&dst, &src, len);
 
 	if (prefault)
 		fn(dst, src, len);