On 13/08/10 08:38, Tatsuo Ishii wrote: >> It's slower than smaller numbers, and if you actually dirty a >> significant portion of it you can have a checkpoint that takes hours to >> sync, completely trashing system responsiveness for a good portion of it. > > So how much is the reasonal upper limit of shared_buffers at this > point? If it's obvious, should we disable or warn to use more than > that number?
Trouble is, there won't be a "reasonable upper limit" ... because it depends so much on the ratio of memory to I/O throughput, the system's writeback aggressiveness, etc etc etc. Personally I've had two Pg machines where one seems to suffer with shared_buffers > 250MB out of 4GB and the other, which has 8GB of RAM, wants shared_buffers to be around 4GB! The main difference: disk subsystems. -- Craig Ringer Tech-related writing: http://soapyfrogs.blogspot.com/ -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
