Where a Timestamp Comes From — Best-Effort Time Versus Bounded Time

Where a Timestamp Comes From — Best-Effort Time Versus Bounded Time A data-flow diagram generated by Archify. 01 / Time Source 02 / Time Service 03 / Local Clock 04 / Using Time GPS Receiver · satellite signal · 01 / Time Source · microsecond GPS Receiver satellite signal microsecond NTP Servers · stratum 1 / 2 · 02 / Time Service · outliers dropped NTP Servers stratum 1 / 2 outliers dropped Wall Clock · time-of-day read · 03 / Local Clock · jumps on reset Wall Clock time-of-day read jumps on reset LWW Timestamps · order by stamp · 04 / Using Time · unsafe if skewed LWW Timestamps order by stamp unsafe if skewed Atomic Clock · local hardware · 01 / Time Source · holdover mode Atomic Clock local hardware holdover mode PTP + ClockBound · hardware timing · 02 / Time Service · bound reported PTP + ClockBound hardware timing bound reported Uncertainty · earliest .. latest · 03 / Local Clock · interval not point Uncertainty earliest .. latest interval not point Commit Wait · wait out the interval · 04 / Using Time · Spanner snapshots Commit Wait wait out the interval Spanner snapshots satellite time source error NTP corrections network delay wall-clock stamps ordering risk disciplined signal hardware bound reported error bound explicit bound wait out the width commit wait Legend primary data policy / PII data flow