Real Time Linux Workshops
1999 - 2000 - 2001 - 2002 - 2003 - 2004 - 2005 - 2006 - 2007 - 2008 - 2009 - 2010
Eighth Real-Time Linux Workshop on October 12 to 15, 2006, in Lanzhou, Gansu, P.R.China
The Real-Time Preemption Patch (preempt-rt)
Thomas Gleixnertglxªlinutronix.de
Two years ago the realtime preemption patch project was started by Ingo Molnar. The patch modifies the Linux Kernel to be fully preemptible and provides realtime capabilities. The main advantage of the patch is the full integration into the POSIX programming environment without seperate APIs. In the early days of the project the patch was discussed quite controversial. The opponents were advocates of dual kernel solutions as well as a large group of mainline kernel developers. The concern of the latter group was that the conversion of spinlocks to sleeping variants would lead to sloppy design and provide an excuse for long held locks. The patch has matured and is used in real world applications. During the last Kernel Summit in Ottawa the complete integration into the mainline kernel was discussed and Linus Torvalds indicated that he has no problem with merging the sleeping spinlocks patch. The paper gives an technological overview over the realtime preemption patch and describes the features which are already integrated into mainline along with a preliminary roadmap for full inclusion.