[smokeping-users] how low can it go?
cam73 at aanet.com.au
Sat Feb 2 05:32:46 CET 2008
Linux ping resolves to 1 microsecond, but the version of fping I am
using with smokeping rounds off to 10 microseconds.
As to accuracy and precision, I am sure each individual measurement is
quite accurate, but I would be wary about attaching too much meaning to
the absolute value - just look for changes.
As examples, 4 machines on a LAN (when everything is quiet):
median and approximate 5th and 95th percentiles.
Server 1: Server 2003: 160us (140-200)
Server 2: Server 2003: 300us (200-400)
Server 3: SBS 2003: 300us (200-400)
Linux server: 330us (310-370)
All windows servers are similar spec with the same NIC. Server 2 is a
bit slower but 1 and 3 are virtually identical hardware.
Prompted by this strange variation, I checked settings and discovered it
was purely the driver versions.
Whether this will make a scrap of difference in real life - who knows?
Aaron Lewis wrote:
> Before I dig into setting up smokeping, I would like to ask if I can
> monitor very small latency numbers--sub millisecond? All nodes are in
> a single building LAN. I need to monitor latency over time to track a
> baseline, compare changes, etc. Everything I've looked at on Windows
> (What's Up Gold, IPCheck) won't measure smaller than 1 ms. Is this
> because the built in PING in windows doesn't resolve lower than 1 ms?
> I notice in any Linux distro, PING gives me numbers like 0.255 ms
> which is great. So will smokeping work at this level?
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