RHEL-RT PersistentParamsHowto

From RHEL-RT

Persistent Tuning

Throughout this collection of howto pages describing how to monitor and tune the realtime system, there are frequent examples demonstrating how to specify kernel tuning parameters. For example:

echo 1 > /proc/irq/1/smp_affinity

That command sets a kernel parameter and the setting will remain in effect until otherwise explicitly changed, or the system reboots. This approach is effective for establishing the initial tuning configuration. In order to have the tuning parameters be persistent across reboots, the following techniques can be utilized to set the parameters at system startup time:

• editing the /etc/sysctl.conf file for the knobs starting with /proc/sys/, replacing '/' with '.' and removing the '/proc/sys/' prefix.

• Editing files in the /etc/sysconfig/ hierarchy. Such cases will be explicitly mentioned in this HOWTO or can be found in the standard RHEL documentation.

• As a last resort, by inserting the respective commands in the /etc/rc.d/rc.local file.

Note: this information is not realtime specific, it is generally applicable to any RHEL variant. This is merely being provided as background information.