[hobbit] vmstat graphing with CPU io wait

[Tom Georgoulias]

Henrik Stoerner wrote:

>  > On RHEL3 (procps-2.0.17-10), there is a value for it in column 14 of
>  > vmstat's output, labeled "wa" under "cpu"
> 
> Aha! So that's it - I had been wondering a bit why my load graphs
> didn't always add up to 100% !
> 
> This is quite interesting, and definitely something that should be
> tracked. So I hope you don't mind that I've tried adding it myself ...

Oh no, please do.  Mine is a hack, your's would be a release.  ;)

So adding the
> cpu_wait data will break any existing vmstat data that has been
> collected. So if we're gonna break the vmstat RRD layout for Linux
> clients, we might as well do it now before the official release.  And
> that should also include getting the very old layout (the one from
> Linux 2.2 kernels, with the "r b w" proces-counts) aligned with the
> new layout - effectively creating a single vmstat RRD format
> regardless of what Linux version you are running.

Good.  Very good.

> So: I've modified the Linux vmstat RRD layout to always include the
> "cpu_w" (from the very old vmstat version) 

Isn't that value the number of processes swapped out, the third column 
from old vmstat?  That is basically going to be ignored, unless someone 
has a custom larrd graph that uses it, right?

and "cpu_wait" columns
> (from the latest vmstat versions). If the client doesn't report a
> value for these, they are set to the special RRD-value "undefined". So
> when someone upgrades a system from Linux 2.2. to 2.4, or from 2.4 to
> 2.6, the vmstat data will still work.

Cool. I'm looking forward to testing it out in the next beta.

Tom