How do you set/change kernel parameters?

Pete Clapham pclapham at
Sat Sep 19 20:36:40 UTC 2009

On Sat, Sep 19, 2009 at 6:04 AM,  <pclapham at> wrote:

> > Hi, all --
> >
> > I am trying to load Oracle on my ubuntu server, and I need to set or change a number of kernel parameters.  Can >anybody tell me where these are to be found, and whether one edits a conf file or uses a system application to change > them?  For example, one parameter that needs to be changed is "semopm", and I can't find a listing of it anywhere in > the documentation.

The "semopm" value is set in /proc/sys/kernel/sem file. It is a kernel
"tunable" - meaning the value can be changed at runtime.

To change the values you can use the following command *as root*:

echo 250 32000 64 256 > /proc/sys/kernel/sem

The 3rd value (64) is the "semopm" setting. Please note that the above
values are arbitrary and for example only, you should use the values
recommended by your database vendor.

Once you are satified with the values you can add a line like -

kernel.sem = 250 32000 64 256

... in the /etc/sysctl.conf file to let the settings get applied on 
every boot.


Didar --

Thank you.  This is very helpful.  Is there a listing of the variables
that can be set in the sysctl.conf file (or any other file)?   The
database requires setting about a dozen kernel parameters, and the man
page for the sysctl.conf file isn't very enlightening.



More information about the ubuntu-users mailing list