Scott, I agree that deriving before input feels contrary to the "Graphite way" since functions are available to perform these actions. However, I put simple value differentiation in the initial release because I feel it would be a significant usability win: you could just click around in the Graphite UX and see graphs of the proper shapes, not a constantly growing "hill," without taking any additional action to apply a function.
Just yesterday I merged contributed code to add yet another differentiation feature, one that writes the time derivative between the difference. A number of people were bothered that Graphite was displaying values off by a factor of the Collectd collection interval (10[s] by default). Practically stated, CPU values were normalized at 1000 instead of 100, etc. Again, this is something that could be corrected by applying a scale on the data in Graphite. But, people /really/ wanted the feature. Both differentiation features can be toggled by plugin options and are off by default. So, users have a choice and everyone is happy, assuming they have Python installed ;) Greg On Fri, Oct 28, 2011 at 9:10 AM, Scott Sanders <jssand...@gmail.com> wrote: > On Fri, Oct 28, 2011 at 1:57 AM, Gregory Szorc <gregory.sz...@gmail.com>wrote: > >> Cool! You may be interested in my similar Python plugin. Mine initially >> had a very similar feature set as yours, but GitHub pull requests have >> slowly trickled in with new features, including deriving values. Feel free >> to reference/copy the ideas! https://github.com/indygreg/collectd-carbon >> > > Thanks, Greg! I started with your plugin and moved to a compiled solution > because python wasn't available on some of the hosts I am monitoring. Your > work was a big help to me and a great source of inspiration. > > I'm curious why you added the ability to send derived values to carbon. > That feels contrary to the "Graphite way" of doing things, since > derivative() and nonNegativeDerivative() provide the same functionality. > > -Scott >
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