Maybe what's needed is a stable and well supported real-time OS. Xenomai might work.
But even better is a more modularized Machine Kit architecture that lets you run the various parts on different computers that each use a different OS. The real time loops could run under a true RTOS, then path planning g-code parsing and graphics could all be done on some other computers or even a couple of them in user space. I'm using an RTOS for some other motion control work and getting much better performance on much less powerful hardware. On Tue, Jul 4, 2017 at 4:57 PM, Todd Zuercher <[email protected]> wrote: > That looks pretty nice. My J1900 board is only around 10us running RTAI. > Maybe I'll have to give it a try. > > But can a Preempt-rt kernel pull off acceptable latency scores (50-100us) on > old hardware? Such as the old P4 box (with ISA slots) I have that runs great > with Lucid (20us), but I can't get the Wheezy RTAI Kernel to work on it at > all. > > ----- Original Message ----- > From: "sam sokolik" <[email protected]> > To: "Enhanced Machine Controller (EMC)" <[email protected]> > Sent: Tuesday, July 4, 2017 6:33:10 PM > Subject: Re: [Emc-users] Maybe we don't need rtai anymore? > > This image got stripped > > http://electronicsam.com/images/KandT/testing/user-04Jul2017-1172.png > > sam > > On 07/04/2017 05:22 PM, sam sokolik wrote: >> I have been playing with linuxcnc for a long time... It has come a >> long way. >> >> Currently the RTAI folks seem to have issues developing. >> >> Now there is RT_Preempt. Couple cool things.. It has been migrated >> to the linux foundation. This means a lot eyes on it. It is also >> pretty easy to build. I have done it quite a few times now. My >> experience is that the out of the box rt_preemt has ok realtime >> performance. Anywhere from 20 to 100us latency. Perfect for >> external interface cards (mesa, pico and such). I have a computer >> that has decent enough rt-preempt performance that it is running 50us >> base thread. (small emco lathe - 100 line encoder for threading) I >> have been running this for quite a while this way with no issues. >> >> Why am I rambling... >> >> Well - I have been playing with debian stretch and 4.9.0-3-rt >> kernel. I booted our matsuura (j1900 quad core) which with no >> tweeking has aprox 100us latency. (it has been running mesa ethernet >> cards with rt_preempt - no issues) Next I booted it with some kernel >> line tweaks. (checking the hardware - processors 0,1 and 2,3 share >> cache. So I added >> >> isolcpus=2,3 idle=poll >> >> The latency on this system was phenomenal. It has been running for >> hours now and still <6us >> >> >> >> these numbers are as good or better than rtai. Could we, with some >> tweaks, use rt_preempt for printer port configs and forget about rtai >> for now? I have more computer hardware I can test - but this is >> pretty awesome. >> >> Good video explaining realtime >> https://www.youtube.com/watch?v=BKkX9WASfpI >> >> Rt-preempt even runs decently on my laptop. I have actually run test >> and real machines with it. (don't mute the speakers though... causes >> huge spikes) >> >> sam >> >> ------------------------------------------------------------------------------ >> >> Check out the vibrant tech community on one of the world's most >> engaging tech sites, Slashdot.org! http://sdm.link/slashdot >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
