In 8/6/15 10:44 AM, William Herrin wrote:
The intermediate cause of the problem was propagation delay (including buffer bloat) which induced an oscillating set of states in the trading software.
The root cause was a flipping jassack trying to out-time his competitors by assuming a degree of instantaneity which proved untrue. Don't do that. Don't make assumptions about network timing. You can count on being wrong. If timing matters to your application, find a way to continuously measure.
Similar things happen when folks decide they are going to twiddle the knobs of NTP's behavior. NTP works locally, and gets/provides information globally. More or less. When folks decide to make a change in its core behavior, the usually don't consider how those changes will affect anybody else. I know enough about this to know I don't know anywhere near enough about it, so I leave the knobs alone. -- Harlan Stenn <stenn@nwtime.org> http://networktimefoundation.org - be a member!