Monitoring busy/pool servers
hmurray at megapathdsl.net
Thu Dec 15 01:07:22 UTC 2016
Context is mrulist not working on ntpq when there are lots of slots.]
> I think you have misdiagnosed this. My testing on your flaky wifi link
> suggested strongly that lots of clients isn't the issue - lots of packet
> dropouts is the issue.
The new ntpq times out when run via localhost.
The old ntpq works over the net.
The old ntpq prints out occasional progress messages, like:
580 (0 updates)
696 (0 updates)
812 (0 updates)
It actually rewrites the same line. I poked return a few times to get that.
The new version never prints out anything so I have no idea if it's making
When it gets to the top of my list, I'll work on it. In the mean time,
anybody who tries to use it on a server with lots of clients should know it
will appear to hang.
> The only way to fix this would be to extend the protocol, give mode 6
> clients a way to request newest first. If we're going to do that we might
> as well support capping the count to be returned.
The problem is what to do when the data you are trying to collect gets
With oldest-first, an old one gets promoted and you get the updated version
as a duplicate. (That's the updates above.) That doesn't work with
I think we could hack it to do something like start at slot N rather than the
end. It would have to do a list traversal from the start to get to the
starting point. That would be tolerable for what we want if we put a
reasonable limit on N.
I think the oldest first will hang if the retrieval is slow enough and the
server is busy enough so that slots get updated faster than it can retrieve
>> The mru sort options are also reversed in some options.
> That's trivial to fix. I already told you how, in fact.
You only pointed me at half the code - the place that sets up the sort. I
haven't found the place that actually does the sort. I think I understand
the setup code. It looks like the actual sort is backwards.
I just need to find/make enough time to learn my way around the new ntpq and
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