http://dtrace.org/blogs/brendan/2011/06/24/load-average-video/
Brendan Gregg, author of the DTrace book, talks about the 1, 5 and 15 minute load averages as reported by tools such as uptime and prstat, and then explains in details how they work on Solaris-based Operating Systems including SmartOS, and reveals why they aren't really 1, 5 and 15 minute averages.
For more Brendan videos, start here: http://dtrace.org/blogs/brendan/2010/10/25/new-videos/
Brendan's blog: http://dtrace.org/blogs/brendan/
