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2008.10.27

Monitor Process Progress on Unix

I often run file-processing commands that take many hours to finish, and I therefore need a way to monitor their progress. The Perkin-Elmer/Concurrent OS32 system I worked-on for a couple of years back in 1993 (don't ask) had a facility that displayed for any executing command the percentage of work that was completed. When I first saw this facility working on the programs I maintained, I couldn't believe my eyes, because I was sure that those rusty Cobol programs didn't contain any functionality to monitor their progress.

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2008.05.16

Open and Closed Source Kernels Go Head to Head

Earlier today I presented at the 30th International Conference on Software Engineering a research paper comparing the code quality of Linux, Windows (its research kernel distribution), OpenSolaris, and FreeBSD. For the comparison I parsed multiple configurations of these systems (more than ten million lines), and stored the results in four databases, where I could run SQL queries on them. This amounted to 8GB of data, 160 million records. (Iíve made the databases and the SQL queries available online.) The areas I examined were file organization, code structure, code style, preprocessing, and data organization. To my surprise there was no clear winner or looser, but there were interesting differences in specific areas.

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2007.08.28

The Treacherous Power of Extended Regular Expressions

I wanted to filter out lines containing the word "line" or a double quote from a 1GB file. This can be easily specified as an extended regular expression, but it turns out that I got more than I bargained for.

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2006.07.23

What Can System Administrators Learn from Programmers?

Although we often hear about program bugs and techniques to get rid of them, we seldom see a similar focus in the field of system administration. This is unfortunate, because increasingly the reliability of an IT system depends as much on the software comprising the system as on the support infrastructure hosting it.

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2004.11.25

Code Reading Example: the Linux Kernel Load Calculation

A colleague's Linux machine was exhibiting a very high load value, for no obvious reason. I wanted to make him point the kernel debugger on the routine calculating the load. It has been more than 7 years since the last time I worked on a Linux kernel, so I had to find my way around from first principles. This is an annotated and slightly edited version of what I did.

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Unless otherwise expressly stated, all original material on this page created by Diomidis Spinellis is licensed under a Creative Commons Attribution-Share Alike 3.0 Greece License.