4.4. Tuning Tasks with Tuna

To change policy and priority information on threads, use the --priority parameter: 
# tuna --threads=pid_or_cmd_list --priority=[policy:]rt_priority
  • The pid_or_cmd_list argument is a list of comma-separated PIDs or command-name patterns.
  • Set the policy to RR for round-robin, FIFO for first in, first out, or OTHER for the default policy.
    For an overview of the scheduling policies, see Section 6.3.6, “Tuning Scheduling Policy”.
  • Set the rt_priority in the range 1–99. 1 is the lowest priority, and 99 is the highest priority.
For example: 
# tuna --threads=7861 --priority=RR:40
To verify the changes you set, use the --show_threads parameter both before and after the modifying --priority parameter: 
# tuna --threads=sshd --show_threads --priority=RR:40 --show_threads

                      thread       ctxt_switches
    pid SCHED_ rtpri affinity voluntary nonvoluntary             cmd 
  1034   OTHER     0  0,1,2,3        12           17            sshd  
                      thread       ctxt_switches
    pid SCHED_ rtpri affinity voluntary nonvoluntary             cmd 
  1034      RR    40  0,1,2,3        12           17            sshd
This allows you to compare the state of the selected threads before and after your changes.