~/talk

Running PTP at scale

on YouTube 24m
Talkat Linux Plumbers Conference 2025 · 2025-12-11..12-13· [networking]

speaker

name:Vadim Fedorenko
links:none on file

resources

video:https://youtu.be/BWfbAP06vSE
slides:none on file

summary

Meta runs PTP to 10 microseconds precision across millions of servers and demonstrates a PTP stack handling 1.5M QPS to a modified PTP (ATSC) grandmaster and SPTP clients, with open hardware and FB clock APIs. Found failures: kernel watchdog scheduled as system work stops ticking (fix: do_work kernel thread with realtime priority), slow PHC reads reduced by caching high bits, and receive-path contention solved with seqlock for timecounter and standard SKB FIFOs.

AI-written summary · about

chapters (10)

  1. 0:00Introduction to PTP at scale
  2. 1:04Why PTP is needed at Meta
  3. 3:14Meta’s time synchronization hardware
  4. 5:09PTP stack and kernel side challenges
  5. 7:45Clock drift due to watchdog scheduling
  6. 10:17Reading PHC time efficiently
  7. 12:33Spin lock issues in time counter access
  8. 15:05FIFO implementations in TX timestamping
  9. 16:58Future testing and improvements
  10. 18:49Q&A on performance and latency

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