[smokeping-users] how low can it go?

Cameron Davidson cam73 at aanet.com.au
Sat Feb 2 05:32:46 CET 2008

Hi Aaron,
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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