Procedure 2.1. Reviewing the System in the GUI

1. The main Tuna window is divided into three sections, for CPU, IRQ, and process information. The sections are divided by grab bars for adjustment. The window itself can also be resized.
   As values in each of the sections change, the entries are shown in bold.
2. The CPU list shows all online CPUs and their current usage.
   The check-box beside the name of the CPU is used to filter the task list at the bottom of the window. Only tasks and IRQs that belong to checked CPUs will be displayed.
   
3. The IRQ list shows all active interrupt requests (IRQs), their process ID (PID) and policy and priority information.
   
4. The task list shows all running tasks.
   When a process is threaded, the task list shows the parent thread with all the children threads collapsed below it. Click on the arrow to the left of the process to expand the thread.
   The task list has a right-click menu. Select Hide kernel threads to hide all kernel threads, and see only user threads. Click Hide kernel threads again to restore the kernel threads. Similarly, Hide user threads will hide all user threads and show only kernel threads. Clicking Hide user threads again will restore the user threads.
   

Procedure 2.2. CPU Tuning in the GUI

1. To isolate a CPU, right click on the selected CPU, and select Isolate CPU from the menu. This will cause all tasks currently running on that CPU to move to the next available CPU. This is achieved through removing the selected CPU from the current affinity mask of all threads, so that they no longer see that CPU as being available.
2. To include a CPU, right click on the selected CPU, and select Include CPU from the menu. This will allow tasks to run on that CPU.
3. To restore a CPU, right click on the selected CPU, and select Restore CPU from the menu. This will restore that CPU to its previous configuration.

Procedure 2.3. IRQ Tuning in the GUI

1. Right click on an IRQ and select Set IRQ Attributes to open the IRQ Attributes dialog box.
   
2. The IRQ Attributes dialog shows current information about the IRQ. It has three adjustable attributes:
   1. Scheduling Policy
      A drop down list of the available policies.
      SCHED_OTHER is the default policy. SCHED_FIFO is a first in/first out realtime policy. A SCHED_FIFO policy with a priority of 1 will always run ahead of SCHED_OTHER. SCHED_RR is a policy where threads of equal priority are treated in a round-robin fashion.
   2. Scheduler Priority
      A drop down list of the available priorities. This attribute will be disabled if the selected IRQ cannot have a set priority.
      Scheduler priorities range from 99 (highest) to 1 (lowest). Priorities can be set for threads that use the SCHED_FIFO or SCHED_RR policies.
   3. Affinity
      A numeric list of CPUs on which the IRQ can be run. This entry can be in the form of a comma-delimited list of CPU numbers, a range separated by a hyphen, or a combination of both. For example: 0, 2-4, 7, 8. This would instruct the IRQ to run on CPUs 0, 2, 3, 4, 7 and 8.
      This field will also accept hex masks. Hex masks must be preceded by Ox in order to be recognised and interpreted correctly. Hex masks that do not use that format will be interpreted as a decimal CPU number.

Procedure 2.4. Task Tuning in the GUI

1. Right click on a task and select Set Process Attributes to open the Process Attributes dialog box.
   
2. The Process Attributes dialog shows current information about the task. It allows you to set scheduling policy, scheduler priority, and CPU affinity for a task or set of tasks.
   1. Thread Selection
      Just the selected thread is selected by default. If the task has more than one thread, use All threads of the selected process to make changes to all of the threads for that task. To use a regular expression (regex) to search for tasks, select All command lines matching the regex below:. This will activate the Command line regex: field and you can enter the regex. This field supports the * and ? wildcards, and will match the entire command line. The task list will update to show only those tasks that match the regex.
   2. Policy, Priority and Affinity
      The Policy drop down box contains the available scheduling policy options.
      The Scheduler Priority drop down box contains the available priorities. This attribute will be disabled if the selected tasks cannot have a set priority.
      The Affinity field contains a numeric list of CPUs on which the selected tasks can be run. This entry can be in the form of a comma-delimited list of CPU numbers, a range using square brackets, or a combination of both.
   3. Task List
      This shows a list of the the tasks currently being adjusted based on the thread and regex selections made.

Procedure 2.5. Saving Changes in the GUI

1. Right-click in the Tuna graphical interface, and select the Save kthreads tunings menu item.
2. Tuna will prompt for a filename and directory. Enter a filename and select the location to save the file. Select OK to continue.
   

Procedure 3.1. Reviewing the System in the CLI

1. Use the --show_threads command to view the current policies and priorities:

   # tuna --show_threads
   		  thread       
   pid SCHED_ rtpri affinity             cmd
   1      OTHER     0      0,1            init 
   2       FIFO    99        0     migration/0 
   3      OTHER     0        0     ksoftirqd/0 
   4       FIFO    99        0      watchdog/0
   

2. Use the --show_irqs command to view the current interrupts and their affinity:

   # tuna --show_irqs
   # users            affinity
   0 timer                   0
   1 i8042                   0
   7 parport0                0
   

Procedure 3.2. CPU Tuning in the CLI

1. Specify the list of CPUs to be affected by the command:

   # tuna --cpus=CPU-LIST --COMMAND

2. To isolate a CPU:

   # tuna --cpus=CPU-LIST --isolate
   

   This command will cause all tasks currently running on that CPU to move to the next available CPU.
3. To include a CPU:

   # tuna --cpus=CPU-LIST --include
   

   This command will allow threads to run on the specified CPU.

Procedure 3.3. IRQ Tuning in the CLI

1. Specify the list of IRQs to be affected by the command:

   # tuna --irqs=IRQ-LIST --COMMAND

2. To move an interrupt to a specified CPU:

   # tuna --irqs=IRQ-LIST --cpus=CPU --move
   

Procedure 3.4. Task Tuning in the CLI

1. To change policy and priority information on threads, use the --priority=[POLICY]:RTPRIO command, where POLICY is the new policy and RTPRIO is the new priority:

   # tuna --threads 7861 --priority=RR:40
   

   Policy can be either RR for round-robin, FIFO for first in/first out, or OTHER for the default policy.
   Priority is a number between 1 (lowest priority) and 99 (highest priority).
   For more information on scheduler policy and priority, see the MRG Realtime Reference Guide.
2. Use the --show_threads command to check the changes:

   # tuna --threads 7861 --show_threads
   
   pid 	SCHED_ rtpri affinity voluntary nonvoluntary   cmd
   7861     RR    40     0xff     33318        16957   IRQ-4 serial
   

Procedure 3.5. Saving Changes in the CLI

• Use the --save or -s parameter with a descriptive filename to save the current configuration:

  # tuna --save=FILENAME

1. Cyclictest must be run as the root user.
2. Running cyclistest without any parameters will create one test thread with a 1ms interval:

   # cyclictest
   policy: other: loadavg: 0.07 0.19 0.29 3/260 27939          
   
   T: 0 (27939) P: 0 I:1000 C:   3279 Min:   1538 Act:1059544 Avg:881375 Max: 1059876
   

   The final column displays the maximum latency.
3. Use the following command to run one test thread per CPU:

   # cyclictest --smp -p75 -m
   policy: fifo: loadavg: 0.01 0.05 0.08 1/338 30074          
   
   T: 0 (30073) P:75 I:1000 C:    821 Min:      6 Act:   39 Avg:   22 Max:      44
   T: 1 (30074) P:75 I:1500 C:    542 Min:      7 Act:   64 Avg:   48 Max:      73
   

4. Use this command on a NUMA system (an AMD system with more than one memory node):

   # cyclictest --numa -p75 -m
   policy: fifo: loadavg: 0.00 0.00 0.00 1/173 25319          
   
   T: 0 (25318) P:75 I:1000 C:   2046 Min:      7 Act:    9 Avg:    8 Max:      12
   T: 1 (25319) P:75 I:1500 C:   1363 Min:      8 Act:   10 Avg:    9 Max:      24
   

1. Start cyclictest with the -v (verbose) parameter. Then use a | (pipe) to send the output to the oscilloscope:

   # cyclictest -t1 -n -p99 -v | oscilloscope >/dev/null
   

   
2. Use the keyboard controls listed in the help section of the oscilloscope to control the output:
   • space: Pause the feed, and display a static graph
   • s: Create a snapshot of the graph. The image will be saved as a PNG in the current directory.
   • r: Reset the oscilloscope
   • q: Quit the program

1. You will need a Bugzilla account. You can create one at Create Bugzilla Account.
2. Once you have a Bugzilla account, log in and click on Enter A New Bug Report.
3. You will need to identify the product in which the bug occurs. MRG Realtime appears under Red Hat Enterprise MRG in the Red Hat products list. It is important that you choose the correct product that the bug occurs in.
4. Continue to enter the bug information by designating the appropriate component and giving a detailed problem description.