vardump gave a good reply: it was about locking the cache of CPU. For any interested, here's a paper with details on what I'm talking about with many methods: http://faculty.cs.tamu.edu/bettati/Courses/663/2009C/Slides/...

Specific example in PPC CPU's: http://www.ibm.com/developerworks/library/pa-ppccache/

Googling "cache locking real time" will give you all kinds of interesting work.