Hi, Tom Lane schrieb: > Robert Lor <Robert.Lor@xxxxxxx> writes: >> 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! > > Those numbers look a bit suspicious --- I'd expect to see some of the > LWLocks being taken in both shared and exclusive modes, but you don't > show any such cases. You sure your script is counting correctly? > Also, it'd be interesting to count time spent holding shared lock > separately from time spent holding exclusive. Is there a test case which shows the contention for this full cached tables? It would be nice to have measurable numbers like context switches and queries per second. Sven.
