On Fri, Apr 18, 2014 at 04:46:31PM +0530, Atri Sharma wrote: > This can be changed by introducing an ageing factor that sees how much time > the > current buffer has spend in shared buffers. If the time that the buffer has > spent is large enough (relatively) and it is not hot currently, that means it > has had its chance and can be evicted. This shall save the new page (3) from > being evicted since it's time in shared buffers shall not be high enough to > mandate eviction and it shall be given more chances. > > Since gettimeofday() is an expensive call and hence cannot be done in the > tight > loop, we can count the number of clocksweeps the current buffer has seen > (rather, survived). This shall give us a rough idea of the estimate of the > relative age of the buffer.
Counting clock sweeps is an intersting idea. I think one concern was tracking hot buffers in cases where there is no memory pressure, and hence the clock sweep isn't running --- I am not sure how this would help in that case. -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
