On Wed, 2010-09-15 at 12:16 -0500, Jon Elson wrote: > Lars Segerlund wrote: > > Hello, > > > > I have a question about EMC and the underlying realtime kernel, since > > the Linux RT-Preempt patches are 'almost' included in the mainline > > now, is there any effort to port EMC to this platform ? > > > Have you checked the interrupt latency performance of the RT-preempt kernel? > The quick web search I did indicated that with some work, some users > have been > able to get latency down "under one millisecond", which is nowhere near what > we need for even servo control. With RTAI, latencies of 10 us or better > seem the norm when > good hardware is selected and the right BIOS functions are turned on/off. > Some of these articles are old, however, and better results may now be > available.
I got it below 20 microseconds when I last tested it with the patches I posted. However, there were still some quirks as in certain actions in the system induced huge latency spikes. However, if one doesn't do those activities, it was fine. (And I think those spikes are being worked on. See the great BKL removement efforts, major locking rewrites currently going on, etc...) > It would be good to actually run some of the RT-preempt tests on > representative hardware > before doing anything further. I was running this on an old Pentium 4 with HT disabled. HT completely kills RT, so it has to be disabled. -- Greetings Michael. ------------------------------------------------------------------------------ Start uncovering the many advantages of virtual appliances and start using them to simplify application deployment and accelerate your shift to cloud computing. http://p.sf.net/sfu/novell-sfdev2dev _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
