Two Weeks in the Kernel

Steve Lawrence suggested I make some notes about my first couple weeks at Sun, while it was still fresh. This seems to be the most appropriate place. He suggested a couple questions to answer for myself:

• What did I learn? I learned quite a lot. A list of quick things:
  • How to use mdb
  • How to use DTrace
  • The SCM tools used at Sun (currently Teamware, transitioning to Mercurial)
  • The build system for all of Solaris (which is the same as OpenSolaris)
  • How to set up a Zone
  • How to divide up processors between the various ways Solaris had to group processes
  • How to use the "One True Keyboard" (UNIX style, Sun Type 7, which has caps lock, control, backspace, backslash, escape, and tilde in what are now unusual places, plus an actual Meta key)
  I also learned a bit about testing with race conditions. Also, after having played with many flavors of Linux over the years, as well as some OpenBSD, FreeBSD, and Mac OS X, I finally got around to using Solaris! So far it's a pleasure to develop, and develop on. Most of the code I've worked with is pretty clean and reasonably well commented. And the crash dump facility actually works properly, and is easy to change settings for (dumpadm(1M)). DTrace makes many steps in the debugging process much easier, and while mdb took a while to adjust to after so many years of using gdb, I've grown to like it as well.
• What were the challenges? Getting used to a new work environment is always a little different. Picking my project for the summer was also a challenge, because there were so many interesting proposals. And of course, once I selected one (more on that when I get the time to write a good technical entry) jumping into a code base as large as Solaris is a lot like jumping into a lake in January in New England.
• What were the new experiences? (good and bad) Builds taking 8 hours was new. This doesn't happen frequently, though, since you can just do the portions you updated after the initial build (as with most build systems) but I'd never worked with such a huge code base before. Being able to see my changes somewhere they were publicly visible, and being able to speak (or blog) to anyone about what I do, has also been a thrill - my main complaint with my previous internship was that I could not (and still can not, and may never be able to) talk about the details of the work I did to people who do not work at that company. Being able to give people links to code on opensolaris.org is the polar opposite of the spectrum. I'm not sure I need the degree of freedom I have, but it's certainly nice.

I was also somewhat surprised, given my previous internship working in filesystems and the interest in filesystems following that experience, I'm a bit surprised that I'm not working on ZFS. Though really, I suppose it's in tune with my other goals for this internship - to try something different. To some degree an internship is to help decide if the work you do there is the sort of work you'd like to do in the long term. I think last summer I reached the conclusion that I enjoy operating systems work - filesystems, kernels and such. I enjoy the problems in those and related areas. So for me this is more about sampling the variety which can be had within that space. And thus far, the Solaris kernel group has been great, and I don't expect that to change.

Posted by csg [Personal] ( June 19, 2007 09:50 PM ) Permalink | Comments[0]