Kernel command-line parameters

For this tutorial we add a couple of Linux Kernel command line parameters for real-time optimization:

  • clocksource=tsc: Sets the Time Stamp Counter (TSC) as the clock source for better precision.

  • tsc=reliable: Marks the TSC as reliable, ensuring it is used consistently.

  • nmi_watchdog=0: Disables the Non-Maskable Interrupt (NMI) watchdog to reduce latency.

  • nosoftlockup: Disables the soft lockup detector to prevent unnecessary interruptions.

  • isolcpus=3: Isolates CPU core 3 from the general scheduler, dedicating it to real-time tasks.

  • rcu_nocbs=3: Prevents the specified CPU core (3) from handling RCU (Read-Copy-Update) callbacks, reducing latency.

  • nohz_full=3: Enables full dynamic ticks on CPU core 3, reducing timer interrupts.

  • irqaffinity=0: Directs all hardware interrupts to CPU core 0, keeping core 3 free for real-time tasks.

These parameters need to be applied by GRUB during boot. To do this:

  1. Edit /etc/default/grub and append the following to GRUB_CMDLINE_LINUX_DEFAULT.

    clocksource=tsc tsc=reliable nmi_watchdog=0 nosoftlockup isolcpus=3 rcu_nocbs=3 nohz_full=3 irqaffinity=0

    The result should look similar to this:

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash clocksource=tsc tsc=reliable nmi_watchdog=0 nosoftlockup isolcpus=3 rcu_nocbs=3 nohz_full=3 irqaffinity=0"

  2. Update grub and reboot the system to apply the optimizations.

    sudo update-grub
sudo reboot