Re: [pcp] Floating point problem

[Ken McDonell <kenj@xxxxxxxxxxxxxxxx>]

On 29/07/14 08:27, Ken McDonell wrote:
> ...
> The options are ...
>
> ...
>
> 3. Extend the derived metrics support.  We already have delta() which
> can be applied to counter metrics and returns the difference in value
> between one pmFetch and the next.  This is closer to the semantics
> Martin needs, but does not include the divide by delta(timestamp) part.
>   I could add rate() as a new intrinsic function for derived metrics
> that does the rate conversion.
>
> With option 3. the derived metric definitions would be something like ...
>
> kernel.pct.cpu.user = 100 * rate(kernel.all.cpu.user) / hinv.ncpu
I have checked in the changes to implement option 3.

It seemed generally useful and not a big change, independent of the 
Netflix folk investigating the option 2. route.