Chapter 16. 20h00 - BOFS: Locating system problems with dynamic instrumentation

BOFS: Locating system problems with dynamic instrumentation

Vara Prasad

project: http://sources.redhat.com/systemtap/

This was a very interesting BOFS session, I wished I had attended the related talk too (but I was at the cairo session instead). They started off talking about a defunct project called KST which placed static probe points into the kernel which provides error and performance information on a running kernel. It analyzes syscalls, locks, and places where blocking occurs. At the same time another project called "System TAP" was being worked on, the work on KST stopped and that project joined SystemTAP which is a more powerful dynamic kernel probing facility. Using SystemTAP a user creates "tap sets" which define events of interest to he observer. This project came about because it has been decreed that static probes are never going to be permitted in the official kernel.

There was lots of lively discussion. Most of it revolved around the fact that almost all kernel subsystem developers want some sort of debugging tools/aides so they invariably go out and create their own tools for the job. As a result we've ended up with a kernel where every subsystem has its own debugging aides with little to no duplication or sharing between any of them. Most of the participants wanted to see the day when a general-purpose framework (such as SystemTAP) would be included and supported in an official kernel which all parts of the kernel could find useful for debug or information purposes.