Re: [pcp] pcp grafana and graphite - How to convert pcp metric values into percent

[Ken McDonell <kenj@xxxxxxxxxxxxxxxx>]

G'day Frank.

On 03/07/14 06:39, Frank Ch. Eigler wrote:
> ...
> Indeed so.  A new issue under contention is whether the client side of
> PMAPI - libpcp - could/should have rate-conversion capabilities, so
> each client programs wouldn't have to reinvent that wheel.
And this direction is something I would strongly support, ... but

One more piece of history (at the risk of boring the readers) ... the 
universal "goodness" of this approach was recognized, er I'd guess 15 
years ago, after we'd repeated similar client-side logic in pmval, then 
pmie, then pmchart, then pmview, then pmdumptext, and then a re-written 
pmview, ...
At that time it was known as the "performance metrics class" and became 
something of the holy grail.
The sad story is that we tried (at least 3 times I believe) to build the 
performance metrics class and failed each time.  The only surviving code 
from these efforts is the libpcp_qmc code in the source tree that is 
used by pmtime, pmchart and pmdumptext (and pmview although that's not 
really in the tree yet).
I wish I had better recall of the reasons for the failures to help 
inform the current deliberations ... but the C vs C++ divide was at 
least part of the problem back then.