TL;DR: We can speed up timestamps on x86 Linux by 30% and maintain the same precision as the standard system clock by implementing our own timers without relying on vDSO. Almost nobody should do this.

Table of contents

Timing the timers

The TSC

When syscalls aren’t

Faster monotonic clocks

Making our own vDSO

Measuring tails

Stable timers

Conclusion

Appendix: Methodology

Timing the timers

One of my pet projects at my last job was to introduce distributed tracing to a low-latency pipeline (think 1–10 microseconds per stage) using OpenTelemetry. As part of this effort I spent a considerable amount of time designing, implementing, and optimising our own C++ tracing client library, as the official one has too much overhead.…