Re: [PATCH v1.1] Randomize memcpy benchmark addresses.

[OndÅej BÃlka <neleai at seznam dot cz>]

I did not pull changes, here is updated version

On Wed, Sep 04, 2013 at 06:31:51PM +0200, OndÅej BÃlka wrote:
> Hi,
> 
> This patch randomizes address for memcpy and clears up unnecessary check
> code in memcpy.
> 
> This makes results more accurate. We need to calculate averages of these
> which I leave to Will.
> 
> OK to commit?
> 
 	* benchtests/bench-memcpy.c: Randomize address.

diff --git a/benchtests/bench-memcpy.c b/benchtests/bench-memcpy.c
index 8cd9c23..44deac6 100644
--- a/benchtests/bench-memcpy.c
+++ b/benchtests/bench-memcpy.c
@@ -16,6 +16,10 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#define SIZE 2000000
+#include <stdint.h>
+
+
 #ifndef MEMCPY_RESULT
 # define MEMCPY_RESULT(dst, len) dst
 # define MIN_PAGE_SIZE 131072
@@ -49,32 +53,30 @@ builtin_memcpy (char *dst, const char *src, size_t n)
 typedef char *(*proto_t) (char *, const char *, size_t);
 
 static void
-do_one_test (impl_t *impl, char *dst, const char *src,
+do_one_test (impl_t *impl, size_t align1, size_t align2,
 	     size_t len)
 {
   size_t i, iters = INNER_LOOP_ITERS;
   timing_t start, stop, cur;
-
-  if (CALL (impl, dst, src, len) != MEMCPY_RESULT (dst, len))
+  static unsigned int r_seed = 42;
+  char *srcs[INNER_LOOP_ITERS];
+  char *dsts[INNER_LOOP_ITERS];
+  int offset1 = 0, offset2 = 0;
+  for (int i = 0; i < iters; i++)
     {
-      error (0, 0, "Wrong result in function %s %p %p", impl->name,
-	     CALL (impl, dst, src, len), MEMCPY_RESULT (dst, len));
-      ret = 1;
-      return;
+      if (!align1)
+        offset1 = rand_r (&r_seed) % 64;
+      srcs[i] = buf1 + (rand_r (&r_seed) % (SIZE / 64)) * 64 + offset1;
+      if (!align2)
+        offset2 = rand_r (&r_seed) % 64;
+      dsts[i] = buf2 + (rand_r (&r_seed) % (SIZE / 64)) * 64 + offset2;
     }
 
-  if (memcmp (dst, src, len) != 0)
-    {
-      error (0, 0, "Wrong result in function %s dst \"%s\" src \"%s\"",
-	     impl->name, dst, src);
-      ret = 1;
-      return;
-    }
 
   TIMING_NOW (start);
   for (i = 0; i < iters; ++i)
     {
-      CALL (impl, dst, src, len);
+      CALL (impl, dsts[i], srcs[i], len);
     }
   TIMING_NOW (stop);
 
@@ -86,27 +88,10 @@ do_one_test (impl_t *impl, char *dst, const char *src,
 static void
 do_test (size_t align1, size_t align2, size_t len)
 {
-  size_t i, j;
-  char *s1, *s2;
-
-  align1 &= 63;
-  if (align1 + len >= page_size)
-    return;
-
-  align2 &= 63;
-  if (align2 + len >= page_size)
-    return;
-
-  s1 = (char *) (buf1 + align1);
-  s2 = (char *) (buf2 + align2);
-
-  for (i = 0, j = 1; i < len; i++, j += 23)
-    s1[i] = j;
-
-  printf ("Length %4zd, alignment %2zd/%2zd:", len, align1, align2);
+  printf ("Length %4zd, aligned %c/%c:", len, align1 ? 'y' : 'n', align2 ? 'y' : 'n');
 
   FOR_EACH_IMPL (impl, 0)
-    do_one_test (impl, s2, s1, len);
+    do_one_test (impl, align1, align2, len);
 
   putchar ('\n');
 }
@@ -117,6 +102,11 @@ test_main (void)
   size_t i;
 
   test_init ();
+  buf1 = malloc (2 * SIZE + 4096);
+  buf2 = malloc (2 * SIZE + 4096);
+  buf1 = buf1 + 4096 - ((uintptr_t) buf1) % 4096;
+  buf2 = buf2 + 4096 - ((uintptr_t) buf1) % 4096;
+
 
   printf ("%23s", "");
   FOR_EACH_IMPL (impl, 0)
@@ -126,17 +116,13 @@ test_main (void)
   for (i = 0; i < 18; ++i)
     {
       do_test (0, 0, 1 << i);
-      do_test (i, 0, 1 << i);
-      do_test (0, i, 1 << i);
-      do_test (i, i, 1 << i);
+      do_test (1, 1, 1 << i);
     }
 
   for (i = 0; i < 32; ++i)
     {
       do_test (0, 0, i);
-      do_test (i, 0, i);
-      do_test (0, i, i);
-      do_test (i, i, i);
+      do_test (1, 1, i);
     }
 
   for (i = 3; i < 32; ++i)
@@ -144,9 +130,7 @@ test_main (void)
       if ((i & (i - 1)) == 0)
 	continue;
       do_test (0, 0, 16 * i);
-      do_test (i, 0, 16 * i);
-      do_test (0, i, 16 * i);
-      do_test (i, i, 16 * i);
+      do_test (1, 1, 16 * i);
     }
 
   do_test (0, 0, getpagesize ());