5.3. Redistributing VDO threads

• Dedicate specific cores to IRQ handling and adjust VDO thread affinity if the core is overloaded. The core is overloaded if the %hi value is more than a few percent higher than on other cores.
• Avoid running singleton VDO threads, for example, vdo:journalQ on busy IRQ cores.
• Keep other thread types off cores busy with IRQs only if the individual CPU use is high.

Procedure

• Set the CPU affinity:

  # taskset -cp <cpu_numbers> <process_id>

  Replace <cpu_numbers> with a comma-separated list of CPU numbers to which you want to assign the process. Replace <process_id> with the ID of the running process to which you want to set CPU affinity.

  For example, to set the CPU affinity for dm-vdo processes on CPU cores 1 and 2:

  # for pid in $(ps -eo pid,comm | awk '/vdo/ {print $1}');
  do
      taskset -cp "1,2" "$pid";
  done

Verification

• Display the affinity set:

  # taskset -cp <cpu_numbers> <process_id>

  Replace <process_id> with the ID of the running process for which you want to display CPU affinity.