Yo Hal! On Fri, 17 Jun 2016 04:05:40 -0700 Hal Murray <[email protected]> wrote:
> [email protected] said: > > Gack. Something about how burst works was bugging me. So I put > > tcpdump on it. I don't see any difference between burst and not > > having burst... I'm not saying it does not do anything, just not > > anything immediately obvious. > > burst only matters if the polling interval is greater than 6. The > burst size is limited to 8 and also limited so that the average > polling rate doesn't exceed the non-burst rate with a polling > interval of 6. The burst (not iburst) size is this calculation: peer->burst = min(1 << (peer->hpoll - peer->minpoll), NTP_SHIFT) - 1; I'm not sure what that really means... NTP_SHIFT is 8, so the max is 8. But that 8 is an exponent, not an integer! That makes max burst 256 I think. > > iburst does have an affect. I see six, (not eight) time requests, > > spaced 2 seconds apart. Sorta like the doc says. > > 6 is what I expect after reading the documentation recently. I may > have said 8 previously. If so, sorry for the confusion. The doc also used to say 8, so you had the wrong answer on the good authority. > > But a second peer ignores the iburst, maybe some rate limit thing? > > Are you using "peer" or "server" in your ntp.conf? Both, depending on the remote server type. The doc said not to burst/iburst with a peer. Eric added a change so ntpd enforces that, so now iburst/burst is ony for servers. > I can't think of any reason for the second (or third...) server > to do anything differently from the first. I'd expect them to be > interleaved. You do have to put iburst on each server line. I had a mix of types for a while, so I could see the differences. I can't say that I see any differences in performance, bu my network is not the kind burst/iburst is supposed to help. RGDS GARY --------------------------------------------------------------------------- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 [email protected] Tel:+1 541 382 8588
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