On Fri, Jul 21, 2006 at 12:56:56AM -0700, Robert Lor wrote: > I ran pgbench and fired up a DTrace script using the lwlock probes we've > added, and it looks like BufMappingLock is the most contended lock, but > CheckpointStartLocks are held for longer duration! Not terribly surprising given that that lock can generate a substantial amount of IO (though looking at the numbers, you might want to make bgwriter more aggressive). Also, that's a shared lock, so it won't have nearly the impact that BufMappingLock does.
> Lock Id Mode Count > ControlFileLock Exclusive 1 > SubtransControlLock Exclusive 1 > BgWriterCommLock Exclusive 6 > FreeSpaceLock Exclusive 6 > FirstLockMgrLock Exclusive 48 > BufFreelistLock Exclusive 74 > BufMappingLock Exclusive 74 > CLogControlLock Exclusive 184 > XidGenLock Exclusive 184 > CheckpointStartLock Shared 185 > WALWriteLock Exclusive 185 > ProcArrayLock Exclusive 368 > CLogControlLock Shared 552 > SubtransControlLock Shared 1273 > WALInsertLock Exclusive 1476 > XidGenLock Shared 1842 > ProcArrayLock Shared 3160 > SInvalLock Shared 3684 > BufMappingLock Shared 14578 > > Lock Id Combined Time (ns) > ControlFileLock 7915 > BgWriterCommLock 43438 > FreeSpaceLock 111139 > BufFreelistLock 448530 > FirstLockMgrLock 2879957 > CLogControlLock 4237750 > SubtransControlLock 6378042 > XidGenLock 9500422 > WALInsertLock 16372040 > SInvalLock 23284554 > ProcArrayLock 32188638 > BufMappingLock 113128512 > WALWriteLock 142391501 > CheckpointStartLock 4171106665 > > > Regards, > -Robert > > > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org > -- Jim C. Nasby, Sr. Engineering Consultant [EMAIL PROTECTED] Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
