Scott Carey wrote:
the OS can either quickly allocate to the process or the page cache from the free buffers, or more slowly take from the page cache, or even more slowly page out a process page.
Aha, now it all makes sense.
I like to use the '5 second rule'. dirty_background_ratio should be sized so that it takes about 5 seconds to flush to disk in optimal conditions. dirty_ratio should be 2x to 5x this depending on your application's needs -- for a system with well tuned postgres checkpoints, smaller tends to be better to limit stalls while waiting for the checkpoint fsync to finish.
Thanks a lot, this is invaluable information. Regards, Mike -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
