phantomfive's Journal: Systemd - Efficiency and Pike's Rules of Programming

(DISCLAIMER: These are my notes and might be wrong.)

Lennart Poettering has never heard of Rob Pike's rules of programming. Let's examine why:

He said, "On my system the scripts in /etc/init.d call grep at least 77 times.... that has to be incredibly slow...., and should be rewritten in C."

You can time it yourself, with this command:

time for i in {1..77}; do grep user /etc/passwd > /dev/null; done

On my machine it takes 0.229 seconds.

Lennart didn't get the speed increase he wanted. From his benchmark report, "booting up with Upstart takes 27s, with systemd we reach 24s." This result isn't too bad: when I've made a similar mistake of writing code before timing anything, ignoring Pike's rules for programming, once I actually slowed the system down.

If you don't measure, you can't optimize.

For entertainment and enlightenment, here is a quote by Ken Thompson talking vaguely about Pike's rules for programming:

Early Unix programmers became good at modularity because they had to be. An OS is one of the most complicated pieces of code around. If it is not well structured, it will fall apart. There were a couple of early failures at building Unix that were scrapped. One can blame the early (structureless) C for this, but basically it was because the OS was too complicated to write. We needed both refinements in tools (like C structures) and good practice in using them (like Rob Pike's rules for programming) before we could tame that complexity.

Pike's Laws

[sjalmond]

I had to look this up: http://users.ece.utexas.edu/~adnan/pike.html [utexas.edu] Rob Pike, of Bell Labs, was one of the guys behind|spreading C and the UNIX philosophy. Worth knowing about.

Re:

[phantomfive]

I agree with you, but that exact link is in the post

Re:

[sjalmond]

And so it is! Many apologies.

Re:

[phantomfive]

No worries. I'm glad to know you found them interesting.