On 05/02/2011 12:53 AM, Adarsh Sharma wrote:
> I am also in need of a proper documentation that explains how to set
> SHMAX and SHMALL variables in Postgres.
>
> What things need to be taken in consideration before doing that ?
> What is the value of SHMAX & SHMALL if u have 16 GB RAM for Postgres
> Server ?
Running the script I provided on a Linux server with 16GB of RAM:
$ cat /proc/meminfo | grep MemTotal
MemTotal: 16467464 kB
$ getconf PAGE_SIZE
4096
$ ./shmsetup
# Maximum shared segment size in bytes
kernel.shmmax = 8431341568
# Maximum number of shared memory segments in pages
kernel.shmall = 2058433
That sets SHMMAX to 50% of total RAM, which should be sufficient for any
reasonable installation of PostgreSQL. shmmall is a similar limit
expressed in system pages instead, so as seen here you have to divide by
the system page size of 4096 to figure it out.
--
Greg Smith 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.us
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