What Is the Difference Between Wall‑Clock Time and Monotonic Time, and Why Is Clock Skew Hard?

Grokking Scalable Systems for Interviews

Ask Author

Back to course home

0% completed

Vote For New Content

What Is the Difference Between Wall‑Clock Time and Monotonic Time, and Why Is Clock Skew Hard?

Wall-clock time (system “real time”) is the machine’s current date/time of day, which can jump forward or backward when the clock is adjusted (by NTP sync, daylight savings, manual change, etc.), while monotonic time is a steadily increasing timer (often since boot) that never goes backwards.

Clock skew is the drift or offset between different clocks (for example, on different servers), which is hard to eliminate because each clock runs at a slightly different rate and network sync protocols can’t perfectly align them.

Wall-Clock Time (Real Time)

Wall-clock time (also cal

.....

.....

.....

Like the course? Get enrolled and start learning!