Divide the lock manager's shared state into 'partitions', so as to

reduce contention for the former single LockMgrLock.  Per my recent
proposal.  I set it up for 16 partitions, but on a pgbench test this
gives only a marginal further improvement over 4 partitions --- we need
to test more scenarios to choose the number of partitions.

1 files changed, 11 insertions, 7 deletions

diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 4cba391048..2cfee41eff 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.84 2005/10/15 02:49:46 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/storage/proc.h,v 1.85 2005/12/11 21:02:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -52,7 +52,8 @@ struct XidCache
  * so that the prepared transactions appear to be still running and are
  * correctly shown as holding locks.  A prepared transaction PGPROC can be
  * distinguished from a real one at need by the fact that it has pid == 0.
- * The semaphore and lock-related fields in a prepared-xact PGPROC are unused.
+ * The semaphore and lock-activity fields in a prepared-xact PGPROC are unused,
+ * but its myProcLocks[] lists are valid.
  */
 struct PGPROC
 {
@@ -86,8 +87,12 @@ struct PGPROC
 	LOCKMASK	heldLocks;		/* bitmask for lock types already held on this
 								 * lock object by this backend */
 
-	SHM_QUEUE	procLocks;		/* list of PROCLOCK objects for locks held or
-								 * awaited by this backend */
+	/*
+	 * All PROCLOCK objects for locks held or awaited by this backend are
+	 * linked into one of these lists, according to the partition number of
+	 * their lock.
+	 */
+	SHM_QUEUE	myProcLocks[NUM_LOCK_PARTITIONS];
 
 	struct XidCache subxids;	/* cache for subtransaction XIDs */
 };
@@ -99,7 +104,7 @@ extern DLLIMPORT PGPROC *MyProc;
 
 
 /*
- * There is one ProcGlobal struct for the whole installation.
+ * There is one ProcGlobal struct for the whole database cluster.
  */
 typedef struct PROC_HDR
 {
@@ -134,8 +139,7 @@ extern bool HaveNFreeProcs(int n);
 extern void ProcReleaseLocks(bool isCommit);
 
 extern void ProcQueueInit(PROC_QUEUE *queue);
-extern int ProcSleep(LockMethod lockMethodTable, LOCKMODE lockmode,
-		  LOCK *lock, PROCLOCK *proclock);
+extern int	ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable);
 extern PGPROC *ProcWakeup(PGPROC *proc, int waitStatus);
 extern void ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock);
 extern bool LockWaitCancel(void);