Setting Clock Source for VMs on Linux x86-64

Oracle recommends that you set the clock source to tsc for better performance in virtual environments (VM) on Linux x86-64.

  1. As the root user, check if the tsc clock source is available on your system.
    # cat /sys/devices/system/clocksource/clocksource0/available_clocksource
    kvm-clock tsc acpi_pm 
  2. If the tsc clock source is available, then set tsc as the current clock source.
    # echo "tsc">/sys/devices/system/clocksource/clocksource0/current_clocksource
  3. Verify that the current clock source is set to tsc.
    # cat /sys/devices/system/clocksource/clocksource0/current_clocksource
  4. Using any text editor, append the clocksource directive to the GRUB_CMDLINE_LINUX line in the /etc/default/grub file to retain this clock source setting even after a reboot.
    GRUB_CMDLINE_LINUX=" rhgb quiet numa=off transparent_hugepage=never clocksource=tsc"