Distributed Systems 3.2: Clock synchronisation

Accompanying lecture notes: www.cl.cam.ac.uk/teaching/212...
Full lecture series: • Distributed Systems le...
This video is part of an 8-lecture series on distributed systems, given as part of the undergraduate computer science course at the University of Cambridge. It is preceded by an 8-lecture course on concurrent systems for which videos are not publicly available, but slides can be found on the course web page: www.cl.cam.ac.uk/teaching/212...

[@meamea5127]

What an amazing videos!! Thanks so much! I learn more in a 15-minute than my entire semester.

[@Yaomuuuuu]

what did u do in ur entire semester then。。。

[@ihsannuruliman4005]

@@Yaomuuuuu he's sleeping or being absent

[@DeepalJayasekara]

Thanks Dr. Kleppmann for the amazing series of lectures.

[@joaofurukawa]

u are the GOAT of DS!

[@alexeiionov9812]

so interesting! thank you so much for posting this series : )

[@gospojken]

This was extremely helpful and comprehensive. Thank you so much!

[@ching-tangwang682]

Thank you Dr. Kleppmann, you really make me get more interested in learning Distributed Systems. I've already bought your published book to study and learn more!

[@7xr1e20ln8]

Thank you. NTP implementation was always like latin to me. But, i understand it much clearly now.

[@khaldrogo9451]

The frequency graph blew my mind. Wow.

[@mkgamesartvisuals]

Love it, thanks for sharing!

[@mostinho7]

6:30 the total network delay can be found by looking at time stamps but this assumes network symmetry
We can estimate what t4 was supposed to be and compare with actual. The estimate is t3+(delta/2). Difference between actual t4 and expected is the clock skew

[@utsavseth7116]

Great work.

[@kevinkaizhou]

Python: time.monotonic() to replace time.time()

[@NitinSatish]

Thanks. I was wondering what the equivalent would be in Python

[@MaxNRG]

time.monotonic_ns() → int
Similar to monotonic(), but return time as nanoseconds.
New in version 3.7.

[@AsemAmr19]

Thanks a lot for this video

[@outrospection4all]

@Martin, thanks for sharing. I'm new to this subject and trying to understand how to convert Time Error (drift in seconds per day) to precision in positioning. There are claims suggesting TE at 10^(-18) provides cm precision. If we multiply 10^(-18)*86400 (sec/day)*speed of light, the precision should sub cm. I would be grateful if you help with a comment or reference. Many thanks.

[@donfeto7636]

Thanks bro you legend

[@naveenkothamasu]

I am thinking resetting the client clock happens if the skew is larger instead of slewing as in smaller skew case is because synchronizing the clocks would take a long time otherwise.

[@jftsang]

In NTP why can you do (t4 - t1) - (t3 - t2) ? First two terms are from the client and second two terms are from the server, and if the two clocks have different rates than aren't you working with different units? Or is the assumption that the rates are 'close enough', i.e. corrections to the corrections are second-order?

[@GooseBerry390]

I can't understand the slew chart at 10:06. If the clock ended being synchronized at ~200th mark (miilisecond?) itself, why was the quartz still ticking slowly until ~650 ms?

[@GooseBerry390]

Monotonic clocks are not affected by steps. But are they affected by slews?

[@ahemednor5201]

🙏🌹🙏

[@tomxu1761]

is the ntp used to sync the time for different timezone or in local network, because I see it accepts up to 1000s which is almost 30 minutes

[@pashazzubuntu]

NTP has no concept of timezone, it's always UTC. The timezone is applied after sync

[@user-sk3yl6ib3m]

icons are watching this video day before day exams

[@ashutech1686]

I need java source code for Clock syncronization