On Sunday 11 October 2009 00:19:57 Michael Buesch wrote: > This patch is an attempt to port EMC to run on realtime capable linux > without a realtime hypervisor. > > Linux-RT currently is not ready to support the hard realtime requirements > of EMC, but I think it's a good idea to start playing with it. > > The patch is based on an earlier patchset published by Jeff. > I'd like to maintain the EMC linux-rt support and other people are welcome to > start working on it, too. > > Latencies currently are more or less crappy, because certain operations > induce _huge_ latency spikes (most likely caused by the remaining huge > locks in the kernel. This is being worked on.) > Here's an example run of the latency test on linux-rt: > http://bu3sch.de/misc/linuxrt-snapshot.png > jitter can be brought into the millisecond range with certain operations, so > there's room for improvement. ;) The screenshot is what I get without > stressing > the system. > > To run EMC on linux-rt, get the latest RT tree > git://git.kernel.org/pub/scm/linux/kernel/git/clrkwllms/rt-linux.git > and compile EMC with the --with-realtime=linux option. > > The patch is at http://bu3sch.de/patches/misc/emc-on-linux-rt.patch
Ok, by disabling hyperthreading (and some changes to the code, but those should not help latency much) I'm down to about 11 microseconds latency with spikes into the 100 microseconds range. So I think it's basically _possible_ to get a setup running with stepper motors over a parport, if those latency spikes are identified and fixed. That's hard, but it doesn't look impossible to me... -- Greetings, Michael. ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
