One-way delay measurement for netperf-wrapper

Toke Høiland-Jørgensen toke at
Mon Dec 2 03:34:10 EST 2013

Hal Murray <hmurray at> writes:

> How long are you running the tests?

Not longer than a few minutes at a time, normally.

> How accurate do you expect the timings to be?

As accurate as possible, I suppose...

> ntpd assumes the network delays are symmetric. It's easy to break that
> assumption by sending a lot of traffic in one direction. ntpd tries to
> avoid that problem. It remembers the last 8 packets to a server and
> uses the one with the shortest round trip time. If you run tests for
> long enough you will overflow that buffer. The time scale is somewhere
> between minutes and hours.

Right, well I'm not too worried then; especially not for the case where
there actually is a well-synchronised clock.

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