Which hardware timer is used for hr timers in linux?

Question

The kernel timers are based on the systick HW timer (systick HW timer block or some other timer) with a resolution of 1 jiffy. In case of hr timers (high resolution timers) the resolution is 1 ns. Which hardware timer is used for the operation of hr timers to get 1 ns resolution? I think the hardware timer used for hr timers vary from platform to platform. Any typical example is fine for me. Also, could you point in code where exactly we declare that hr timers use that particular hardware timer?

Answer 1

The resolution is just labelled as 1 ns; the actual resolution depends on the hardware.

High-resolution timers use a clock events device, which is registered by clockevents_register_device.

On x86, this is typically the per-CPU local APIC timer.