[collectd] Problem with [new] ping plugin

Florian Forster octo at verplant.org
Sun Apr 20 10:37:55 CEST 2008


Hi Piotrek,

On Wed, Apr 16, 2008 at 11:49:45AM +0200, Piotrek Kaczmarek wrote:
> At 4am i've changed collectd 3.7.2 (with ping plugin using libping) to
> collectd 3.11 (with ping plugin using liboping). New version works
> quite strange. This is ping graph that shows ping to server itself. I
> think liboping gives bad results (7ms to localhost?). What do you
> think?

one reason I abandoned `libping' was because it returned unrealistic
values[1]. On my machine, pinging the physical interface (i. e. not the
loopback interface) takes about 0.07 milliseconds. So your 7ms look like
a scaling problem.. Can you use the `oping' binary (it's in the `oping'
package) to ping the same address? It uses the same library, so if that
works, the problem is not in the library. If that returns unrealistic
high values, too, the problem at least *definitely* is in the library ;)

Also, could you add an external host, i. e. a host where the packets
actually need to go over the network, so that you can see if they are
off by a factor of ~100, too?

Regards,
-octo

[1] Since it doesn't check the sequence number in the packets, it *may*
    return a packet already in the socket buffer - effectively always
    returning *very fast* - i. e. `1 ms' (or whatever the scaling) in
    your case.
-- 
Florian octo Forster
Hacker in training
GnuPG: 0x91523C3D
http://verplant.org/
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