Optimization is a mess, so use a library for it - but which?

After looking at several open-source candidates, I settled with NLopt. Strong points are

• No 3rd party dependencies, no need to have BLAS crap installed
• Reasonable documentation, accessible, simple tutorial that just works
• can do many different optimization algorithms, LS-BFGS among them; supports derivative-free and gradient based methods
• C and C++ interfaces (should be also callable from Python and MATLAB, haven't tried)
• LGPL license

posted at: 23:43 | path: /academic | permanent link

I find this particular paper by Nightingale (Microsoft Research) quite interesting (will be presented at EUROSYS '11); it analyses data collected by the Windows Error Reporting system (crash dumps) to look at CPU, DRAM and disk failure rates.

Some of the things learnt:

• don't overclock (failure rate increases > 10x)
• brand-name machines are more reliable
• laptop computers are more reliable

Another interesting piece of work is Google's Failure Trends in a Large Disk Drive Population, FAST '07.

posted at: 16:11 | path: / | permanent link

It becomes increasingly harder to operate your own, small SMTP server. Large providers (gmail, hotmail) depend on IP repudation lists and as a small VPS operator your are in a large pool with other people. Interestingly, the US is the worst spam country.

multirbl.valli.org looks interesting too.

On the other hand, I did not have trouble sending email... hello, can you hear me?

posted at: 10:45 | path: /rant | permanent link