Throughput-Delay Curves

A colleague of mine at Yahoo.com asked me if I'd ever seen curves like this:

Not only is the answer, yes (it's a throughput-delay plot or XR plot in my notation), but that particular plot comes from my GCaP course notes. There, I use it to analyze the comparative performance of a functional multiprocessor (NS6000) and a symmetric multiprocessor (SC2000). Note how the two curves cross at around 1500 OPS. You can ask yourself why and if you can't come up with an explanation, you should be registering for a Guerrilla class. :)

The above XR plot also serves as a useful reminder that the throughput and response-time metrics are not only dependent on one another, but they are generally dependent in a nonlinear way—despite what some experts may claim:

My Year in Review 2011

Some days I wonder if I ever actually accomplish anything anymore. Maybe it's time to just pack it in and become a greeter at Walmart. I know a bit about how queues work, so that should put me a few notches ahead of the competition. And I would expect the competition to be fierce because it's a pretty cushy job; but not every day, apparently.

Before taking the big leap, I decided it might be a good idea to note down some of the technical projects I've worked on this year (over and above the daily grind):

A List of CaP Skills

This question popped up recently on Linkedin:

"Can someone tell me what skill set should a Performance and Capacity Analyst have and develop throughout his career?"

and I realized that, although I have a kind of list in my head, and I talk about such skills in my classes, I have been too lazy to write them down anywhere; which is pretty dumb. I must try to do something about that (New Year resolution? What are the odds?). In some ways, my fallback is the online Guerrilla Manual. Anyway, here is my (slightly edited) response to the LI question, and let it therefore constitute my first attempt at writing down such a list.

Season's Greetings 2011

Best wishes to all my blog readers and Guerrilla class alumni during this 2011 holiday season. I look forward to more of the same next year.

Image: The winter lights of Silicon Valley, California, from Mt. Hamilton webcam courtesy of UC Regents and Lick Observatory.

Webinar: Load Testing Meets Data Analytics

This Thursday, October 27 at 10 am PDT^*, I'll be participating in a webinar sponsored by SOASTA, Inc. They make a new breed of load-testing product called CloudTest® which, despite its name, is not restricted to load testing cloud-based apps, although it can do that too.

Kanban Revived in an Agile Kind of Way

I just returned from a workshop on the latest in web technologies (invitation only) where I was surprised to hear reference made to kanban. Kanban is a card-based system originally developed by Toyota in the 1950s for controlling their manufacturing lines. I have a note about it in the "Brief History of Buffers" section of my Perl::PDQ book because it is a logical precursor to JIT scheduling and compiling. I will also discuss it in the up-coming Guerrilla classes.

Now, it seems kanban has been revived under the "agile" banner for making software development more efficient. Of course, the concept of using cards to capture dev state information is not entirely new, even in the context of software engineering. So-called Snow Cards are another card-based technique used to monitor the software development process.

Visual Illusions: Google vs Facebook vs Yahoo

The ability to visualize data, enabled by the advent of graphical computer tools, has been a great boon to Cap and Perf. The power derives from the way graphical displays provide an efficient impedance match to the visual system in our brain. The weakness derives from the way graphical displays provide an efficient impedance match to the visual system in our brain. We can get carried away by visual representations alone. Every marketing organization exploits that weakness. Numbers do have poor cognitive impedance, but that doesn't mean numbers should ignored altogether. In fact, we often need a combination of both numerical and visual data representations so that we don't suffer visual miscues and thus jump to the wrong conclusion. The following presents an example of how easily this can happen.

Recently, Guerrilla alumnus, Scott J. pointed me at this Chart of the Day showing how Google revenue growth was outpacing both Facebook and Yahoo, when compared 7 years after launching the respective companies.

Clearly, this chart is intended to be an attention getter for the Silicon Alley Insider website but, it looks about right and normally I might have just accepted the claim without giving it anymore thought. The notion that Google growth is dominating, is also consistent with a lot of other things one sees. No surprises there.