From: "John Ackermann N8UR" <[EMAIL PROTECTED]>
Karel Sandler wrote:
From: "Ask Bjørn Hansen" <[EMAIL PROTECTED]>
On Jul 17, 2006, at 4:57 PM, Karel Sandler wrote:
An average load from the pool is low (~7rps for my S2) but also highly
non-uniform.
Yes, that's another TODO item.
I'm surprised by your numbers though. I have a server that's in the
pool.ntp.org zone constantly and it's getting less than 1000rps (or it
was last I was looking...)
The numbers mentioned on the pool pages are true assuming a ~5 minute
average is used. I was curious about a structure of this "standard"
peaks. A few examples with 1 minute average or even 1 second average are
located here: http://lx.ujf.cas.cz/ntp-lx/spikes . The utmost I've seen
so far - 1080 requests during one single second. Such extrema occur
sometimes but always precisely at a full hour, probably due to a large
number of ntpdate or sntp users with their periodic jobs.
For what it's worth, I plot the average number of clients and number of
requests per second for my S2 server (which is in the global pool) at
http://www.febo.com/time-freq/ntp/stats/clients/index.html. The data
comes from Wayne Schlitt's ntp_scripts package. My average
requests/second hovers a little below 10, with spikes from 80 to 100 for
the hours when I'm in the DNS. My average number of clients runs from
2000-2500, with spikes up beyond 5000 when I'm in the DNS.
I think that the US pool servers get somewhat higher load than elsewhere
because the ratio between a number of the clients using just the US zone and
the number of the servers there is high.
What is the averaging time for your rps values? Sometimes you can get say
6000 requests per minute although 1500 of them arrived at one single second.
For such a case even xx/1 Mbps line is slow, any packets get an asymmetric
delay. Of course, this is not a problem for any ntpd client with a good
configuration.
--
Karel Sandler
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