Chapter 3. Reviewing a system by using the tuna interface The tuna tool reduces the complexity of performing tuning tasks. Use tuna to adjust scheduler tunables, tune thread priority, IRQ handlers, and to isolate CPU cores and sockets. By using the tuna tool, you can perform the following operations: List the CPUs on a system. List the interrupt requests (IRQs) currently running on a system. Change policy and priority information about threads. Display the current policies and priorities of a system. 3.1. Installing the tuna tool The tuna tool is designed to be used on a running system. This allows application-specific measurement tools to see and analyze system performance immediately after changes have been made. Procedure Install the tuna tool: Verification Display the available tuna CLI options: Additional resources tuna(8) man page on your system 3.2. Viewing the system status by using the tuna tool You can use the tuna command-line interface (CLI) tool to view the system status. Prerequisites The tuna tool is installed. For more information, see Installing the tuna tool . Procedure View the current policies and priorities: Alternatively, to view a specific thread corresponding to a PID or matching a command name, enter: The pid_or_cmd_list argument is a list of comma-separated PIDs or command-name patterns. Depending on you scenario, perform one of the following actions: To tune CPUs by using the tuna CLI, complete the steps in Tuning CPUs by using the tuna tool . To tune the IRQs by using the tuna tool, complete the steps in Tuning IRQs by using the tuna tool . Save the changed configuration: This command saves only currently running kernel threads. Processes that are not running are not saved. Additional resources tuna(8) man page on your system 3.3. Tuning CPUs by using the tuna tool The tuna tool commands can target individual CPUs. By using the tuna tool, you can perform the following actions: Isolate CPUs All tasks running on the specified CPU move to the available CPU. Isolating a CPU makes this CPU unavailable by removing it from the affinity mask of all threads. Include CPUs Allows tasks to run on the specified CPU. Restore CPUs Restores the specified CPU to its configuration. Prerequisites The tuna tool is installed. For more information, see Installing the tuna tool . Procedure List all CPUs and specify the list of CPUs to be affected by the command: Display the thread list in the tuna interface: Specify the list of CPUs to be affected by a command: The cpu_list argument is a list of comma-separated CPU numbers, for example, --cpus 0,2 . To add a specific CPU to the current cpu_list , use, for example, --cpus +0 . Depending on your scenario, perform one of the following actions: To isolate a CPU, enter: To include a CPU, enter: To use a system with four or more processors, make all ssh threads run on CPU 0 and 1 and all http threads on CPU 2 and 3 : Verification Display the current configuration and verify that the changes were applied: # tuna show_threads -t ssh * pid SCHED_ rtpri affinity voluntary nonvoluntary cmd 855 OTHER 0 0,1 23 15 sshd # tuna show_threads -t http\ * pid SCHED_ rtpri affinity voluntary nonvoluntary cmd 855 OTHER 0 2,3 23 15 http Additional resources /proc/cpuinfo file tuna(8) man page on your system 3.4. Tuning IRQs by using the tuna tool The /proc/interrupts file records the number of interrupts per IRQ, the type of interrupt, and the name of the device that is located at that IRQ. Prerequisites The tuna tool is installed. For more information, see Installing tuna tool . Procedure View the current IRQs and their affinity: Specify the list of IRQs to be affected by a command: The irq_list argument is a list of comma-separated IRQ numbers or user-name patterns. Replace [ command ] with, for example, --spread . Move an interrupt to a specified CPU: Replace 128 with the irq_list argument and 3 with the cpu_list argument. The cpu_list argument is a list of comma-separated CPU numbers, for example, --cpus 0,2 . For more information, see Tuning CPUs by using the tuna tool . Verification Compare the state of the selected IRQs before and after moving any interrupt to a specified CPU: Additional resources /procs/interrupts file tuna(8) man page on your system

Commands:
dnf install tuna
tuna -h
tuna show_threads 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
tuna show_threads -t pid_or_cmd_list
tuna save filename
ps ax | awk 'BEGIN { ORS="," }{ print USD1 }' PID,1,2,3,4,5,6,8,10,11,12,13,14,15,16,17,19
tuna show_threads -t 'thread_list from above cmd'
*tuna [ command ] --cpus cpu_list *
tuna isolate --cpus cpu_list
tuna include --cpus cpu_list
tuna move --cpus 0,1 -t ssh * tuna move --cpus 2,3 -t http\ *
tuna show_threads -t ssh * pid SCHED_ rtpri affinity voluntary nonvoluntary cmd 855 OTHER 0 0,1 23 15 sshd tuna show_threads -t http\ * pid SCHED_ rtpri affinity voluntary nonvoluntary cmd 855 OTHER 0 2,3 23 15 http
tuna show_irqs users affinity 0 timer 0 1 i8042 0 7 parport0 0
tuna [ command ] --irqs irq_list --cpus cpu_list
tuna show_irqs --irqs 128 users affinity 128 iwlwifi 0,1,2,3 tuna move --irqs 128 --cpus 3
tuna show_irqs --irqs 128 users affinity 128 iwlwifi 3