On Fri, Apr 22, 2011 at 5:21 AM, drvillo <f.vivoli@xxxxxxxxx> wrote: > -given the configuration attached (which is basically a vanilla one) and the > number of buffers written at each execution, are these execution times > normal or above average? They seem fine. Remember that the write is deliberately spread out; it's not as if the system couldn't write out 130-160 8k blocks in less than 30 s. > -in the case of the execution that overruns past the timeout, what are the > implications wrt the client application? Not sure what you are referring to here. > -AFAIU client connections are basically stalled during checkpoints. Is it > reasonable to infer that the fact that the application blocking on a > getConnection() might be related to checkpoints being executed? > -considering some tuning on the PG side, should I try increasing > checkpoint_timeout and rising checkpoint_completion_target to lessen the > impact of IO on the client or should I shorten the period so there's less > stuff to write? from the number of buffers written on average I'd assume the > first option is the one to go for but I might miss some bit of reasoning > here... I'm a bit puzzled by all of this because the logs you posted seem to reflect a system under very light load. Each checkpoint is writing no more than 4% of shared_buffers and the sync phases are generally completing in less than one second. I don't see why that would be causing stalls. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
