changing max_connections in postgresql on FreeBSD 5.4

From: Claus Guttesen (kometen_at_gmail.com)
Date: 08/04/05

  • Next message: Sean Chittenden: "Re: changing max_connections in postgresql on FreeBSD 5.4" 
    Date: Thu, 4 Aug 2005 19:01:29 +0200
To: freebsd-performance@freebsd.org

    Hi.

    I recently lowered max_connections from 1024 to 384 in
    /usr/local/pgsql/data/postgresql.conf. The server is a quad opteron @
    2 GHz and 4 GB of RAM.

    This decreased the SIZE and RES values in top and it seems that the
    current max_connections is more than adequate. To see how many
    concurrent connections the db-server had I did a 'netstat -na|grep -i
    establi|wc -l' which showed some 230 established connections during
    peak.

    In order to use max_connections set to 1024 I had to raise the
    following values in the kernel:

    options SHMMAXPGS=327680
    options SEMMNI=200
    options SEMMNS=1200
    options SEMUME=200
    options SEMMNU=600

    The values were taken from the postgresql-ports-installation-notes and
    were simply increased to fit the max_connections-parameter in
    postgresql.conf.

    Will more RAM become available to postgresql if I change the
    kernel-values mentioned above to half the size?

    The server does occasionally become loaded with load-averages around 6
    or 7 but usually stays below 4. Disk-io is not a problem, usually
    remains below 1 MB/s, cpu-idle is approx. 5-10 % during peak and
    around 80 % idle otherwise.

    regards
    Claus
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  • Next message: Sean Chittenden: "Re: changing max_connections in postgresql on FreeBSD 5.4"

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