[collectd] how to limit display to a particular range of values

[florian iragne]

Florian Forster a écrit :
> Hi Florian,
> 
> On Tue, Dec 09, 2008 at 04:25:58PM +0100, florian iragne wrote:
>> I've a VE which is the collectd Master, and all other are clients
>> (about 15 VE). Everything is fine except the display of cpu usage.
>> Indeed, i have values of several billions % for io-waits. I don't
>> understand why since the VE are not under a heavy load.
> 
> that's weird. Do other tools, such as `top' and `mpstat', report correct
> values for IO-wait?

I would say yes, but since it seems to be a on-value-peak, i cannot be sure.

It happens at least once per hour, so that the cpu usage graph is 
completely unusable most of the time, which is bad for me since thesse 
are cpu-intensive VEs.

> We can't sanely limit the `cpu' ``type'' to a small maximum value,
> because CPU time is not measured in percent but in jiffies, the unit
> used by the scheduler. This is a common misconception, because under
> many distributions the Linux kernel is configured to have
> (approximately) 100 jiffies per second.

Well, i know it's not sane to put suche a limit, but in my case it would 
help a lot.

--snip--

>> I'm using collectd 3.10.4-1 from debian etch and display the values
>> with collection.cgi
> 
> Sorry, I didn't see that comment in time: No, using 3.* there is no way
> to specify that except compiling the daemon yourself and editing the
> source code of the cpu plugin. The comment above only apply for 4.*.

Or maybe, is it possible to do such a filter in the collection.cgi module?

thanks for your answers

Florian