Which clock source is more reliable?

Issue

• Which clock source for e.g. HPET vs. TSC is more reliable?
• basically 'hpet' does consume more cpu time than 'tsc'. that means that 'hpet' is not useful as a clocksource. right?
  but I think in some workload or some environment, 'hpet' is useful perhaps. is it right? or nope?
• my question is that when I should consider to change the clocksource between 'tsc' and 'hpet'? or Do I just use 'tsc' as clocksource always?