[smokeping-users] Huge latency increase when additional targets added

[G.W. Haywood]

Hi there,

On Wed, 9 Jul 2008, V.v Kotrla wrote:

> I've noticed 50 % increase in graphed latency (see example[1]) after
> I've added some 10 more targets. (Is this expected behavior?)

That isn't a huge increase.  The RTTs depend entirely on what the
hardware is doing, and what it is capable of doing.  I'm not a bit
surprised that you're seeing an increase in MEDIAN latency and also
in the variability of the RTT figures (more smoke:).  Try looking
at the graphs while you slowly add one host at a time.  Take some
screenshots for each situation after it has been running for a few
hours, so that you can get a feel for the steady-state condition.
Then load the network with soem traffic and see what happens.

> I'm running smokeping 2.0.9 on Debian Etch machine, network interface
> is some Intel Fast Ethether on-board device.

I run Etch on a couple of machines and one of them is my Smokeping
master - but I'm using the latest version of Smokeping, it's quite
easy to install it on Debian.  I also posted modifications here on
the list a few weeks back which permit reasonable rendering of the
graphs with logarithmic scales if you're interested.  Sometimes my
network RTTs would go right off the scale on a linear graph:

http://www.jubileegroup.co.uk/JOS/misc/webserver_logarithmic_graph.gif

Something like this is nothing to wory about as long as you know
what's happening in there.

--

73,
Ged.