Monday, November 7, 2011

User authority for operating system real-time capabilities

Low-latency-sensitive applications will try to pin all their memory and use (through chrt or
sched_setscheduler()) real-time priorities for application threads.

To enable this capability, create a group with these special privileges and add the required users to this
group. Typical values for this privileged group can be set in a configuration file as follows:

TIMEOUT=unlimited # in minutes
RT_PRIORITY=100
NICE=-20
MEMLOCK=unlimited
cat >>/etc/security/limits.conf <<EOF
@realtime soft cpu $TIMEOUT
@realtime - rtprio $RT_PRIORITY
@realtime - nice $NICE
@realtime - memlock $MEMLOCK
EOF

User profiles can then be added to the realtime group with usermod:
usermod -g realtime <userid>

Users must sign out and then sign back into the system for these changes to take effect.

For more information about the limits.conf file, see the limits.conf man page.

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