- George Neville-Neil, “Computers, Clocks, and Network time – Everything you never wanted to know about time.” Most people who work with computers have no idea how the computers keep time. All networked computer systems require some form of temporal synchronization. As networks have gotten faster the demands for accurate, distributed, timekeeping have increased, but most programmers have no idea about the quality of the clocks in their systems, nor how they might be kept in sync. This talk will go over the basics of computer clocks, why they’re inaccurate, and what can be expected from various strategies for getting systems into sync.
- Martin Burnicki, “Technical Aspects of Leap-Second Propagation and Evaluation.” Leap seconds are scheduled by the International Earth Rotation Service (IERS) whenever the difference between true earth rotation and the UTC time scale reaches a certain limit. Whenever a leap second has been scheduled by the IERS, a warning must be disseminated to time keeping devices so that clocks become aware of the scheduled leap second early enough to be able to handle the leap second properly. There are different ways to propagate the leap second warnings, and there are different ways to apply leap second adjustments. Various ways folks have badly handled leap seconds will also be described.
- Poul-Henning Kamp, “Ntimed – an NTPD replacement.” The first release of ntimed-client is ready for initial use. Learn more about the Ntimed effort, which includes the leaf-node client, and eventually a slave process that can serve time to other NTP clients, and eventually a master process that will talk to refclocks.
- Harlan Stenn, “NTF’s General Timestamp API and Library – Current timestamps suck. We can do much better.” A good timestamp can be a very useful thing. Unfortunately, most current timestamps don’t have enough information in them to be very useful, and they don’t “age well”‘ and are too often not useful outside of the context of where they were taken. After decades of casual thought, Harlan started to document what information would be needed to have a useful timestamp, and what sort of underlying support would be necessary to produce and use them. This turned in to a GSoC project in 2013 where a proof-of-concept user-level library was produced, and some work was done to implement the new timestamp format as a core kernel timekeeping structure in a Linux kernel.
- Tom Van Baak, “Precise Time, From CPU clocks to Hacking the Universe.” Time is the most precisely measured quantity we have, yet it is still the most mysterious. Precise time and frequency are the hidden ingredient in most technology used today, from computer synchronization, to satellite navigation, to data communications, to digital music and video. In this talk we explore the amazing world of precise time, a world that anyone with curiosity can explore on their own.
It is not uncommon for ham radio operators, electrical engineers, or physicists to encounter the details about precision timing. But it turns out that playing with computer hardware and operating system software is also a wonderful entry into the obscure world of nanoseconds and parts per million accuracy.
We hope to see you there!
FOSDEM 2015 Schedule of Time track talks