Function devices::tsc::calibrate::calibrate_tsc_frequency

fn calibrate_tsc_frequency(
    rdtsc: fn() -> u64,
    core: usize,
    num_samples: usize,
    calibration_duration: Duration,
    stdev_limit: f64,
) -> Result<(i128, Vec<TscMoment>), TscCalibrationError>

Calibrate the TSC frequency of core.

This function first pins itself to core, generates num_samples start TscMoments, sleeps for calibration_duration, and then generates num_samples end TscMoments. For each pair of start and end moments, a TSC frequency value is calculated. Any frequencies that are outside of stddev_limit standard deviations from the median offset are discarded, because they may represent an interrupt that occurred while a TscMoment was generated. The remaining non-discarded frequencies are then averaged. The function returns the TSC frequency average, as well as a Vec of TscMoments, which are all of the end moments that were associated with at least one non-discarded frequency.

Arguments

• core - Core that this function should run on.
• rdtsc - Function for reading the TSC value, usually just runs RDTSC instruction.
• num_samples - Number of start and end TscMoments to generate.
• calibration_duration - How long to sleep in between gathering start and end moments.
• stdev_limit - Number of standard deviations outside of which frequencies are discarded.