On 5/15/2012 2:05 PM, Tux Lab wrote: > thanks for the link. I've tried so many different way to compile > rtai, ie via debian's repository and downloading from original source > that I'm a bit lost right now. However it good to know that at > least someone else is running EMC on debian, so it's a doable task :) > > Anyway, I just got the latency test to run, but it looks pretty bad. > ovl max at 174,383. Now I have to figure out how I got RTAI to work > and duplicate it on another system.
It's good to see you're making progress. Is this perhaps a laptop? By any chance, did you boot the LinuxCNC LiveCD on the same machine and run the latency test from there to see how the numbers compare? What is your hardware platform, actually? > Does the graphics card driver makes any difference on latency? As I > run glxgear, I notice the fps is pretty low and it's running software > rendering. If I switch over to radeon driver will latency improve? > does kernel timer frequency have an effect on the latency? > > thanks, > > John > Yes, graphics card drivers can affect the latency, some very badly, but the devil depends on the details of how they diddle with the machine. You say "radeon driver". Are you using the proprietary NVidia driver? As posted on the wiki, this driver has been reported in the past to break real-time constraints (although they keep releasing new versions and we've not been good at keeping straight which ones are bad). Try the "nv" or "vesa" drivers instead if you have Radeon graphics. You could also boot the LinuxCNC LiveCD on the system and see what driver Ubuntu chooses. By itself, software rendering itself is probably not the issue. For example, I have a copy of LinuxCNC2.4.6 running on an old Dell Pentium IV desktop system with an NVidia GeForce FX 5200 graphics card. Ubuntu detects the card and loads the "nouveau" driver. The combination does not support 3D acceleration in hardware and yields quite modest frame rates. However, I get reasonable latency numbers, about twice the numbers I and others get with Intel Atom boards and their built-in Intel GMA graphics, still good enough for software stepping. Regards, Kent ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
