Vol. 8 No. 6 – June 2010


Collecting Counters:
Gathering statistics is important, but so is making them available to others.

Over the past month I’ve been trying to figure out a problem that occurs on our systems when the network is under heavy load. After about two weeks I was able to narrow down the problem from "the network is broken" (a phrase that my coworkers use mostly to annoy me), to being something that is going wrong on the network interfaces in our systems.

by George Neville-Neil

The Ideal HPC Programming Language:
Maybe it’s Fortran. Or maybe it just doesn’t matter.

The DARPA HPCS program sought a tenfold productivity improvement in trans-petaflop systems for HPC. This article describes programmability studies undertaken by Sun Microsystems in its HPCS participation. These studies were distinct from Sun’s ongoing development of a new HPC programming language (Fortress) and the company’s broader HPCS productivity studies, though there was certainly overlap with both activities.

by Eugene Loh

You’re Doing It Wrong:
Think you’ve mastered the art of server performance? Think again.

Would you believe me if I claimed that an algorithm that has been on the books as "optimal" for 46 years, which has been analyzed in excruciating detail by geniuses like Knuth and taught in all computer science courses in the world, can be optimized to run 10 times faster? A couple of years ago, I fell into some interesting company and became the author of an open source HTTP accelerator called Varnish, basically an HTTP cache to put in front of slow Web servers. Today Varnish is used by Web sites of all sorts, from Facebook, Wikia, and Slashdot to obscure sites you have surely never heard of.

by Poul-Henning Kamp