Again improve MemSet comments.

src/include/c.h

@@ -12,7 +12,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: c.h,v 1.127 2002/10/08 19:17:58 momjian Exp $
+ * $Id: c.h,v 1.128 2002/10/08 23:12:22 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -572,10 +572,11 @@ typedef NameData *Name;
  *	Exactly the same as standard library function memset(), but considerably
  *	faster for zeroing small word-aligned structures (such as parsetree nodes).
  *	This has to be a macro because the main point is to avoid function-call
- *	overhead.
+ *	overhead.   However, we have also found that the loop is faster than
+ *	native libc memset() on some platforms, even those with assembler
+ *	memset() functions.  More research needs to be done, perhaps with
+ *	platform-specific MEMSET_LOOP_LIMIT values or tests in configure.
  *
- *	We got the MEMSET_LOOP_LIMIT value by testing this against the libc
- *  memset() on several platforms, some with assembly language versions.
  *	bjm 2002-10-08
  */
 #define MemSet(start, val, len) \