"Joshua D. Drake" <jd@xxxxxxxxxxxxxxxxx> writes: >> I use RHEL 4. I can not understand how the scalability related with >> shared memory? > It isn't RHEL4 and shared memory. It is PostgreSQL and shared memory. > Things have changed with PostgreSQL since 7.3 (7.3 is really god awful > old) that allow it to more effectively access shared memory and thus > provide better performance. Some specifics: * bufmgr algorithms redesigned to allow larger number of shared buffers to be used effectively * bufmgr redesigned to not have a single lock for management of all shared buffers; likewise for lockmgr * lots of marginal tweaks such as paying attention to cache line alignment of "hot" shared data structures I'm probably forgetting some things but I think the bufmgr and lockmgr changes were the biggest improvements in this area. regards, tom lane
