Thank you so much for the script. ~deepak
On Jan 22, 2011, at 10:18 AM, Greg Smith <g...@2ndquadrant.com> wrote: > DM wrote: >> RAM = 16GB, what value should i set for shmall? > > Given that PostgreSQL rarely sees increasing improvement as shared_buffers > goes over 50% of RAM, I just use that figure for the shmall and then compute > shmmax based on the page size to match it. I use the attached script to do > all the hard work, haven't found a Linux system yet it didn't do the right > thing on. It sounds like you might have the math on the relation between the > two backwards, look at the output and code of this once and that should sort > things out for you. > > -- > Greg Smith 2ndQuadrant US g...@2ndquadrant.com Baltimore, MD > PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us > "PostgreSQL 9.0 High Performance": http://www.2ndQuadrant.com/books > > #!/bin/bash > > # Output lines suitable for sysctl configuration based > # on total amount of RAM on the system. The output > # will allow up to 50% of physical memory to be allocated > # into shared memory. > > # On Linux, you can use it as follows (as root): > # > # ./shmsetup >> /etc/sysctl.conf > # sysctl -p > > # Early FreeBSD versions do not support the sysconf interface > # used here. The exact version where this works hasn't > # been confirmed yet. > > page_size=`getconf PAGE_SIZE` > phys_pages=`getconf _PHYS_PAGES` > > if [ -z "$page_size" ]; then > echo Error: cannot determine page size > exit 1 > fi > > if [ -z "$phys_pages" ]; then > echo Error: cannot determine number of memory pages > exit 2 > fi > > shmall=`expr $phys_pages / 2` > shmmax=`expr $shmall \* $page_size` > > echo \# Maximum shared segment size in bytes > echo kernel.shmmax = $shmmax > echo \# Maximum number of shared memory segments in pages > echo kernel.shmall = $shmall -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
