If CLOCK_MONOTONIC goes backwards your platform's implementation is broken. As defined in POSIX it does not ever go backwards. It counts the time since an unspecified point in the past that never varies after system start-up.
If your process is rescheduled to a different CPU, it must still go forwards regardless of TSC variance between the CPUs.
Of course if your uptime hits 68 years or so, the clock will wrap. If your app can't have any downtime in 68 years though I hope you've got the budget to think about this sort of thing :)
If your process is rescheduled to a different CPU, it must still go forwards regardless of TSC variance between the CPUs.
Of course if your uptime hits 68 years or so, the clock will wrap. If your app can't have any downtime in 68 years though I hope you've got the budget to think about this sort of thing :)