The Pith of Performance

Wednesday, July 29, 2009

Remembering Mr. Erlang as a Unit

Not to be confused with Frank Zappa's daughter or a Coneheads spousal unit, is the Erlang unit. The number of Erlangs (E) is defined as:

E = λ S,

(1)

and is a well-known in the teletraffic industry, where it was first used as a measure of call capacity. For this reason, it's also called the traffic intensity.

Scalability in a Spreadsheet - Google Style

Speaking of spreadsheets, it's always nice when someone, who uses your ideas, takes the time to write to you about it. Case in point, Scott Roberts sent me the following email, telling me how he'd set up my USL model in Google Docs spreadsheets.

Ignite! San Jose 2009: The Afterburn

It's been over a month since I did the Ignite event in San Jose, but I have simply had so many things to do since then, that I'm only catching up on blogging about it now.

The title of my Ignite talk was "Scalability for Quantheads: How to Do It Between Spreadsheets" (a pitch for applying my Universal Scalability Law to Web 2.0 applications using Excel spreadsheets). Since scalability is about sustainable size, I used the theme of giants as a hook. Why are there no 30 ft (10 m) giants like the one in the "Jack and the Beanstalk" fairytale? Officially, there have been no human giants taller than 10 feet (3 m); and even they need leg supports. The reasons are given in my Chap. 4 of my Guerrilla Capacity Planning book.

A Thomas Jefferson Enigma for July 4th

This post isn't about computer performance per se, although see end, and I certainly have better things to do with my time, but when I read this slashdot item about a 200 year old cipher, I couldn't help wondering what it would look like as a modern computer algorithm.

PDQ 5.0 Test Suite or ... How I Spent My Weekend

I was planning to blog about the amazing time I had at Velocity 2009 last week, when this landed in my mailbox (edited for space and privacy):

Subject: Seeking help with PDQ-R ... Date: Thu, 25 Jun 2009 15:51:21 -0500 My name is James and I've been trying to learn to properly use PDQ after reading two of your books, "Guerrilla Capacity Planning" and "Analyzing Computer System Performance with Perl::PDQ." I'm still getting a grip on PDQ-R. ... I decided to set about of re-creating the queue circuit in the study with PDQ-R as an exercise. ... The output of my code yields: [1] "Manual response time for class 1 is 0.864179 seconds" [1] "PDQ-R response time for class 1 is 0.313637 seconds" [1] "Manual response time for class 2 is 6.105397 seconds" [1] "PDQ-R response time for class 2 is 3.552873 seconds" [1] "Manual response time for class 3 is 4.535833 seconds" [1] "PDQ-R response time for class 3 is 4.535833 seconds" If you could give my code a look over and give me some hints I would really appreciate it.

August Guerrilla Class: Using R for Performance Analysis

Registrations are still open for the Guerrilla Data Analysis Techniques (GDAT) class being held August 10-14, 2009. The focus will be on using R and the new release of PDQ-R for performance analysis and capacity planning.

All Guerrilla classes are held at our Larkspur Landing location in Pleasanton, California; a 45-minute BART ride to downtown San Francisco.

(Click on the image for details)
For those of you coming from international locations, here is a table of currency EXCHANGE rates. We look forward to seeing all of you in August!