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
>
>
>
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--
Jim C. Nasby, Sr. Engineering Consultant jnasby@pervasive.com
Pervasive Software http://pervasive.com work: 512-231-6117
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