This sounds very much like a realtime latency issue. You have the same effect if the video card doesn't play well with the realtime kernel on a normal system (like video cards that share video memory with system memory). You get latency spikes. Have you tried running the latency test while doing opengl stuff? - GLXGEARS is one - some of the opengl screen savers also show issues.. I bet you see the same issue the pc hardware does.
At the fest when they where working on the mazak - Jeff E was alt-tabbing between 2 windows and the machine was going Thud - Thud - Thud each time. (finally JMK yelled at him to stop :) ) They went to the 2nd hand computer store and bought a video card and the problem was solved. (not that you have that option...) sam On 08/11/2013 08:19 AM, Charles Steinkuehler wrote: > On 8/5/2013 11:29 AM, Charles Steinkuehler wrote: >> How does LinuxCNC behave under heavy CPU load? >> >> I am experiencing some errors in my 3D prints that look very much like >> part of the gcode got lost or skipped over* (I'll try to post pics or a >> video). This is happening a few times in multi-hour prints, so I >> haven't yet actually _seen_ this happen, I just see the results in the >> final print. >> >> I have not gotten any real-time errors or warnings, so I don't think >> it's anything at the HAL level or below, but on the BeagleBone, the CPU >> usage easily hits 100%, and the SD-card "hard disk" is also pretty slow >> (note that I am printing gcode files in the 2 MB to 10 MB size range, >> with lots of small line segments). > I am revisiting this issue after experimenting with some alternate user > interfaces and a discussion with David Bagby. > > David indicated he would repeatedly run a familiar gcode program on his > shapoko and it would sometimes just "sound wrong". I have also tested a > variety of interfaces and noticed that if I am running a program in the > mini interface and I enable the "backplot" display, it causes the > steppers to dramatically slow down and/or stutter, and change from their > 'singing' tones to more of a 'grinding' type noise while the backplot is > initially loading. > > I'm pretty sure the problem isn't in the hard real time xenomai HAL > thread. If the PRU code is running and the xenomai task is blocked or > halted the steppers would just keep going at their current speed, likely > resulting in a following error once the ARM core 'catches up'. The fact > that the motors are 'stuttering' as they slave to the commanded position > indicates to me that the HAL servo thread is running properly but the > planned motion points are not being properly updated. > > I am also fairly certain the motion queue is being kept full by the > user-mode code. In particular, the issue can happen in the middle of a > long G1 move, so the queue shouldn't be a factor. > > Questions: > ========== > * What exists between the motion queue and the HAL servo thread that > could potentially be blocked under high load conditions? AFAIK, > everything from the motion queue down to HAL is supposed to be hard real > time, right? > > * Can anyone else running a BeagleBone system try using the mini GUI and > enabling the backplot while a program is running? I'd like to know I'm > not the only one seeing this issue. > > * Also, could someone on a traditional x86 system try this test? I > suspect it will work OK, but it would still be interesting to know if > the problem shows up or not. > > > > ------------------------------------------------------------------------------ > Get 100% visibility into Java/.NET code with AppDynamics Lite! > It's a free troubleshooting tool designed for production. > Get down to code-level detail for bottlenecks, with <2% overhead. > Download for free and get started troubleshooting in minutes. > http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk > > > _______________________________________________ > Emc-developers mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-developers ------------------------------------------------------------------------------ Get 100% visibility into Java/.NET code with AppDynamics Lite! It's a free troubleshooting tool designed for production. Get down to code-level detail for bottlenecks, with <2% overhead. Download for free and get started troubleshooting in minutes. http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
