[collectd] CPU Graphs seems out of sync

[Shibashish]

Thank you Florian for the update. In my case, only 2 or 3 servers out of 10
are showing the discrepancy. The hardware, OS, collectd and related versions
are same. Please see the attached images.

--
Shib


On Tue, Jun 3, 2008 at 11:17 PM, Florian Forster <octo at verplant.org> wrote:

> Hi Shibashish,
>
> On Tue, Jun 03, 2008 at 12:49:29PM +0530, Shibashish wrote:
> > In the CPU graphs, in some (2) of the hosts, the vertical axis starts as
> 0,
> > 200, 400, 600, 800. And one of the host shows as 0, 0.5k, 1.0k. Why is
> this
> > so ? How can percent go beyond 100 ? Or is the plotting showing correct
> data
> > ? Is there a way to correct this ?
>
> the CPU plugin collects ``jiffies'' or ``system timer interrupts''.
> Typical values for a Linux kernel are 1/100s and 1/250s, but you can set
> this to 1/1000s for (near) realtime systems, too.
>
> So there are 100, 250, or 1000 jiffies in one second. So given the
> values I'd guess that the kernel of your distribution is built with the
> HZ variable set to 1000 at build time. Unfortunatly I don't know how you
> can double check this, but I'm sure Google will be able to assist you ;)
>
> You can convert this number to a percentage, which is easier to compare
> between machines, using RRDTool's ``RPN'' functionality. You'd need to
> do something along these lines:
>  sum=user,syst,+,idle,+
>  user_pct=user,sum,/,100,*
>  syst_pct=syst,sum,/,100,*
>  idle_pct=idle,sum,/,100,*
> Then graph `user_pct', `syst_pct', and `idle_pct'.
>
> Regards,
> -octo
> --
> Florian octo Forster
> Hacker in training
> GnuPG: 0x91523C3D
> http://verplant.org/
>
>
>
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