Index: ./src/backend/storage/lmgr/s_lock.c
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/backend/storage/lmgr/s_lock.c,v
retrieving revision 1.22
diff -u -r1.22 s_lock.c
--- ./src/backend/storage/lmgr/s_lock.c	23 Dec 2003 22:15:07 -0000	1.22
+++ ./src/backend/storage/lmgr/s_lock.c	27 Dec 2003 10:28:54 -0000
@@ -76,7 +76,7 @@
 	 * The select() delays are measured in centiseconds (0.01 sec) because 10
 	 * msec is a common resolution limit at the OS level.
 	 */
-#define SPINS_PER_DELAY		100
+#define SPINS_PER_DELAY		1000
 #define NUM_DELAYS			1000
 #define MIN_DELAY_CSEC		1
 #define MAX_DELAY_CSEC		100
@@ -86,7 +86,7 @@
 	int			cur_delay = MIN_DELAY_CSEC;
 	struct timeval delay;
 
-	while (TAS(lock))
+	while (!S_LOCK_FREE(lock) || TAS(lock))
 	{
 		if (++spins > SPINS_PER_DELAY)
 		{
@@ -111,6 +111,7 @@
 
 			spins = 0;
 		}
+		CPU_DELAY();
 	}
 }
 
Index: ./src/include/storage/s_lock.h
===================================================================
RCS file: /projects/cvsroot/pgsql-server/src/include/storage/s_lock.h,v
retrieving revision 1.123
diff -u -r1.123 s_lock.h
--- ./src/include/storage/s_lock.h	23 Dec 2003 22:15:07 -0000	1.123
+++ ./src/include/storage/s_lock.h	27 Dec 2003 10:28:55 -0000
@@ -52,6 +52,15 @@
  *	in assembly language to execute a hardware atomic-test-and-set
  *	instruction.  Equivalent OS-supplied mutex routines could be used too.
  *
+ *	Additionally, a platform specific delay function can be defined:
+ *
+ *	void CPU_DELAY(void)
+ *		Notification that the cpu is executing a busy loop.
+ *
+ * 	Some platforms need such an indication. One example are platforms
+ * 	that implement SMT, i.e. multiple logical threads that share 
+ * 	execution resources in one physical cpu.
+ *
  *	If no system-specific TAS() is available (ie, HAVE_SPINLOCKS is not
  *	defined), then we fall back on an emulation that uses SysV semaphores
  *	(see spin.c).  This emulation will be MUCH MUCH slower than a proper TAS()
@@ -115,6 +124,17 @@
 	return (int) _res;
 }
 
+#define HAS_CPU_DELAY
+
+#define CPU_DELAY()	cpu_delay()
+
+static __inline__ void
+cpu_delay(void)
+{
+	__asm__ __volatile__(
+		" rep; nop			\n"
+		: : : "memory");
+}
 #endif	 /* __i386__ || __x86_64__ */
 
 
@@ -715,6 +735,9 @@
 #define TAS(lock)		tas(lock)
 #endif	 /* TAS */
 
+#ifndef HAS_CPU_DELAY
+#define CPU_DELAY()	do { } while(0)
+#endif
 
 /*
  * Platform-independent out-of-line support routines