## Saturday, April 21, 2018

### Virtual cloudXchange 2018 Conference

Our abstract has been accepted for presentation at the first CMG cloudXchange Virtual Conference to be held on June 19, 2018.

## Exposing the Cost of PerformanceHidden in the Cloud

Neil Gunther
Performance Dynamics, Castro Valley, California

Mohit Chawla
Independent Systems Engineer, Hamburg, Germany

Whilst offering versatile elastic capacity, the cloud also reintroduces an old mainframe concept—chargeback—which rejuvenates the need for performance analysis and capacity planning. Combining production JMX data with an appropriate performance model, we show how to assess fee-based EC2 configurations for a mobile-user application running on a Linux-hosted Tomcat cluster. The performance model also facilitates ongoing cost-benefit analysis of different AWS Auto Scaling policies.

## Wednesday, March 14, 2018

### WTF is Modeling, Anyway?

A conversation with performance and capacity management veteran Boris Zibitsker, on his BEZnext channel, about how to save multiple millions of dollars with a one-line performance model (at 21:50 minutes into the video) that has less than 5% error. I wish my PDQ models were that good. :/

The strength of the model turns out to be its explanatory power, rather than prediction, per se. However, with the correct explanation of the performance problem in hand (which also proved that all other guesses were wrong), this model correctly predicted a 300% reduction in application response time for essentially no cost. Modeling doesn't get much better than this.

### The Original Analysis

In 2013, a Redmonk blogger claimed that the growth of GitHub (GH) users follows a certain type of diffusion model called Bass diffusion. Here, growth refers to the number of unique user IDs as a function of time, not the number project repositories, which can have a high degree of multiplicity.

In a response, I tweeted a plot that suggested GH growth might be following a power law, aka scale free growth. The tell-tale sign is the asymptotic linearity of the growth data on double-log axes, which the original blog post did not discuss. The periods on the x-axis correspond to years, with the first period representing calendar year 2008 and the fifth period being the year 2012.

## Saturday, October 8, 2016

### Crib Sheet for Emulating Web Traffic

Our paper entitled, How to Emulate Web Traffic Using Standard Load Testing Tools is now available online and will be presented at the upcoming CMG conference in November.