On 10.10.2012 09:12, Strahinja Kustudić wrote: > Hi everyone, > > I have a Postgresql 9.1 dedicated server with 16 cores, 96GB RAM and > RAID10 15K SCSI drives which is runing Centos 6.2 x64. This server is > mainly used for inserting/updating large amounts of data via > copy/insert/update commands, and seldom for running select queries. > > Here are the relevant configuration parameters I changed: > > shared_buffers = 10GB > effective_cache_size = 90GB > work_mem = 32MB > maintenance_work_mem = 512MB > checkpoint_segments = 64 > checkpoint_completion_target = 0.8 > > My biggest concern are shared_buffers and effective_cache_size, should I > increase shared_buffers and decrease effective_cache_size? I read that > values above 10GB for shared_buffers give lower performance, than > smaller amounts? > > free is currently reporting (during the loading of data): > > $ free -m > total used free shared buffers cached > Mem: 96730 96418 311 0 71 93120 > -/+ buffers/cache: 3227 93502 > Swap: 21000 51 20949 > > So it did a little swapping, but only minor, still I should probably > decrease shared_buffers so there is no swapping at all. That's hardly caused by shared buffers. The main point is that effective_cache_size is just a hint to the optimizer how much cache (shared buffers + page cache) to expect. So it's unlikely PostgreSQL is going to allocate 100GB of RAM or something. What have you set to the main /proc/sys/vm/ parameters? Mainly these three: /proc/sys/vm/swappiness /proc/sys/vm/overcommit_memory /proc/sys/vm/overcommit_ratio Tomas -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
