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From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Hal Murray <hmurray@megapathdsl.net>
Cc: bloat-devel@lists.bufferbloat.net
Subject: Re: One-way delay measurement for netperf-wrapper
Date: Mon, 02 Dec 2013 08:34:10 +0000	[thread overview]
Message-ID: <87ob4z1wjh.fsf@toke.dk> (raw)
In-Reply-To: <20131202054526.523C0406060@ip-64-139-1-69.sjc.megapath.net> (Hal Murray's message of "Sun, 01 Dec 2013 21:45:26 -0800")

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Hal Murray <hmurray@megapathdsl.net> 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.

-Toke

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  reply	other threads:[~2013-12-02  8:34 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-02  5:45 Hal Murray
2013-12-02  8:34 ` Toke Høiland-Jørgensen [this message]
  -- strict thread matches above, loose matches on Subject: below --
2013-11-28 20:30 Hal Murray
2013-11-28 18:51 Toke Høiland-Jørgensen
2013-11-29  8:45 ` Eggert, Lars
2013-11-29  9:42   ` Toke Høiland-Jørgensen
2013-11-29 10:20     ` Eggert, Lars
2013-11-29 13:04       ` Toke Høiland-Jørgensen
2013-11-29 14:30         ` Eggert, Lars
2013-11-29 16:55           ` Dave Taht
2013-12-02 18:11     ` Rick Jones
2013-12-02 18:20       ` Toke Høiland-Jørgensen

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