From: Vladimir Serbinenko <phcoder@gmail.com>
Date: Sun, 1 Aug 2010 14:44:36 +0000 (-0500)
Subject: * kern/misc.c (grub_memset): Optimise to reduce cache stalls.
X-Git-Tag: 1.99~696
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=7decd202a72cbed9d1e1d445d6fbea9532703866;p=thirdparty%2Fgrub.git

* kern/misc.c (grub_memset): Optimise to reduce cache stalls.
	Also-By: Colin Watson <cjwatson@ubuntu.com>
---

diff --git a/ChangeLog b/ChangeLog
index 20094fec8..d00fd9d51 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2010-08-01  Vladimir Serbinenko  <phcoder@gmail.com>
+2010-08-01  Colin Watson  <cjwatson@ubuntu.com>
+
+	* kern/misc.c (grub_memset): Optimise to reduce cache stalls.
+
 2010-08-01  Robert Millan  <rmh@gnu.org>
 
 	Prevent accidental use of uninitialized libzfs_handle.
diff --git a/kern/misc.c b/kern/misc.c
index c13c96e30..b37ef230c 100644
--- a/kern/misc.c
+++ b/kern/misc.c
@@ -518,12 +518,39 @@ grub_strndup (const char *s, grub_size_t n)
 }
 
 void *
-grub_memset (void *s, int c, grub_size_t n)
+grub_memset (void *s, int c, grub_size_t len)
 {
-  unsigned char *p = (unsigned char *) s;
+  void *p = s;
+  grub_uint8_t pattern8 = c;
 
-  while (n--)
-    *p++ = (unsigned char) c;
+  if (len >= 3 * sizeof (unsigned long))
+    {
+      unsigned long patternl = 0;
+      grub_size_t i;
+
+      for (i = 0; i < sizeof (unsigned long); i++)
+	patternl |= ((unsigned long) pattern8) << (8 * i);
+
+      while (len > 0 && (((grub_addr_t) p) & (sizeof (unsigned long) - 1)))
+	{
+	  *(grub_uint8_t *) p = pattern8;
+	  p = (grub_uint8_t *) p + 1;
+	  len--;
+	}
+      while (len >= sizeof (unsigned long))
+	{
+	  *(unsigned long *) p = patternl;
+	  p = (unsigned long *) p + 1;
+	  len -= sizeof (unsigned long);
+	}
+    }
+
+  while (len > 0)
+    {
+      *(grub_uint8_t *) p = pattern8;
+      p = (grub_uint8_t *) p + 1;
+      len--;
+    }
 
   return s;
 }