Boolean function for the rescue

The problem is defined as follows: a set of features is saved using bit-sets (usually large), and there is a list/map/whatever of sets containing features of different objects. We have to find which features are unique. Read more...

Scalar version of SSE move mask instruction

SSE instruction PMOVMSKB gathers all most significant bits from bytes and stores them as a single 16-bit value; similar action is performed by MOVMSKPD and MOVMSKPS.

Such operation could be easily done using scalar multiplication. Read more ...

Set of great articles

Lockless Inc publish a lot of interesting, advanced articles. There are some low-level things, algorithms, threading, and many more. Definitely worth to read!

Internal memory fragmentation

In previous post I've advertised my text about trie representations.

Depending on particular representation internal memory fragmentation vary from 25% to 46% (in GNU libc). In other words if trie should occupy 100MB then in the worst case real memory usage is around 200MB. I've never suppose that fragmentation could be so significant.

When quite simple memory pools were used, then internal fragmentation has been cut down to 1-2%! Impressive.