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 -c -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	26 Dec 2003 22:24:52 -0000
***************
*** 76,82 ****
  	 * 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 NUM_DELAYS			1000
  #define MIN_DELAY_CSEC		1
  #define MAX_DELAY_CSEC		100
--- 76,82 ----
  	 * 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		1000
  #define NUM_DELAYS			1000
  #define MIN_DELAY_CSEC		1
  #define MAX_DELAY_CSEC		100
***************
*** 111,116 ****
--- 111,117 ----
  
  			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 -c -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	26 Dec 2003 22:24:52 -0000
***************
*** 52,57 ****
--- 52,66 ----
   *	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()
***************
*** 115,120 ****
--- 124,140 ----
  	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__ */
  
  
***************
*** 715,720 ****
--- 735,748 ----
  #define TAS(lock)		tas(lock)
  #endif	 /* TAS */
  
+ #ifndef HAS_CPU_DELAY
+ #define CPU_DELAY() cpu_delay()
+ 
+ static __inline__ void
+ cpu_delay(void)
+ {
+ }
+ #endif
  
  /*
   * Platform-independent out-of-line support routines