Sunday, May 1, 2011

Fundamental Performance Metrics

Baron Schwartz invited me to comment on his latest blog post entitled "The four fundamental performance metrics," which I did. Coincidentally, I happened to address this same topic in my presentation at CMG Atlanta last week. I claim there are really only 3 fundamental performance metrics (actually 2, if you want to get truly fundamental about it).

Here are the relevant slides from that talk, which I hope you will be able to compare with Baron's perspective.

Baron seems to be getting his cue from certain Linux kernel metrics. However, I would strongly caution against using metrics defined by Linux kernel hackers (or any other hackers, for that matter). I've seen too many examples of bastardized nomenclature, not to mention broken code that incorrectly computes said metrics. Moreover, I see no virtue in reinventing the wheel only to end up with an irregular polygon.

With that in mind, what I think Baron is trying to elucidate is that just a small number of simple performance metrics (4?) is all that is required to parameterize certain performance models, such as the USL scalability model. In other words, performance modeling may not be as far away from your already collected performance data as you might think, and therefore there is little excuse not to do it. Amen to that!

I'll be discussing this topic again in my Guerrilla Boot Camp class, later this week.

1 comment:

Baron said...

I've updated my blog post to correct the things you pointed out. I still haven't found a good short phrase for what I call the weighted time. Caution about Linux kernel docs duly noted :-)