[ntp:questions] .1 Microsecond Synchronization
david at ex.djwhome.demon.co.uk.invalid
Thu Jun 4 21:26:27 UTC 2009
> To do this the order in which market data was received and trades
> transmitted need to be maintained. I do know from their current log
Remember that London and New York are, maybe 15 milli-lightseconds
apart. Even before allowing for cable routing and velocity factors,
you don't need 100ns accuracy to prove non-causality.
> files that 1 ms is not fine enough for this and that on occasion .1
> ms is not good enough. They currently are using a feature of the
> processors that seems to return clock tick on the microprocessor
> (Some assembly language instruction). They have an algorithm for
RDTSC. ntpd/Linux/FreeBSD kernels use this as one of their methods to
interpolate hardware clock ticks.
> controlling the skew that occurs using this method. This seems to
> meet there needs in a single server scenario but when going across
> machines this will obviously not work.
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