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Archive for February, 2009

TraceVis: performance visualization for TraceMonkey

I’ve been working on a visualization of TraceMonkey performance, with the goal of revealing what the JS VM is doing, and why it runs certain programs fast or slow, so we can figure out how to make the slow ones fast too. In this post, I want to show off the results and explain how […]

SunSpider Statistics, Part II

In my last post, I laid out some questions I wanted to answer. I decided to tackle these questions empirically, by running SunSpider 100 times with –runs=10, for a total of 1000 test suite runs, and then see if SunSpider’s confidence intervals and tests come out as predicted. Empirical methods are nice because you can […]

SunSpider Statistics, Part I: Questions

The TraceMonkey project uses SunSpider regularly to measure JavaScript performance. The problem is that the results are often hard to interpret. Is an 11 ms improvement a real speedup or just random? We all have our intuitions about how to use the numbers, but I wanted to try a little statistics on the problem. The […]