Hallo, this is the plot from this board with a slightly different cpu, under reasonable load: https://www.osadl.org/Latency-plot-of-system-in-rack-4-slot.qa-latencyplot-r4s7.0.html You might look up there also exactly how they do their tests.
The Pagefault message says that the LCNC memory is not properly locked in place (i.e. the kernel needs to page, it should not) So I would say, speak to your friendly software developer, or if you really want to try, throw lots of memory at it and hope the kernel stops paging after a while. By the way you can also look up the kernel compile switches here: https://www.osadl.org/Profile-of-system-in-rack-4-slot-7.qa-profile-r4s7.0.html and try to build a new kernel. At first I thought the problem might be there, but the pagefault message convinced me otherwise. cheers, j. On Fri, Sep 14, 2012 at 6:30 AM, Kent A. Reed <kentallanr...@gmail.com>wrote: > Gentle persons: > > First, a statement. > > On my ASUS AT5NM10-I board (Intel Atom D510 CPU, 2GB RAM, yada yada > yada) I followed in Charles Steinkeuhler's footsteps > ( > http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Debian_Wheezy_Linux-Rt_Compile_LinuxCNC > ) > to build a 64-bit Debian Wheezy RT PREEMPT Linux system running the > 3.2.0-3-rt-amd64 kernel and Linuxcnc 2.6.0~pre. Such a build has given > Charles some decent albeit not (yet) great latency numbers on several > non-Atom boards. > > My ASUS board has given me excellent latency results with what I'll call > classic Ubuntu 10.04LTS LinuxCNC running the 2.6.32-122-rtai kernel: sub > 10us for both threads with Hyperthreading disabled in the BIOS and one > cpu isolated during the boot process. > > With the RT PREEMPT system, this board gives lousy results even running > headless. Using latency-test, for some minutes I see the base (25us) > thread showing a max latency of anywhere from 25us to 40us and the servo > (1000us) thread 40us to 50us. Then, the servo thread pops a bit and the > base thread pops a lot, to about 110us. At the same time, the kernel > throws three lines to the console > > "ERROR: Missed scheduling deadline for task 0 [nnnn times] > "Now is xxxxx.xxx, deadline is xxxxx.xxx > "Absolute number of pagefaults in realtime context: 1030" > > This process repeats but not at regular intervals. Using latencyplot, I > can see that, with nothing else running, both threads mostly show good > latency numbers, typically < 10us, once we've settled down after > invoking latencyplot. If I run a copy of glxgears, the servo thread > latency gets jumpy but stays below about 40us. Running several copies of > glxgears doesn't seem to cause any more damage, nor does invoking du or > some other disk access-intensive command. Sooner or later, though, the > above big-time event happens. Repeat ad nauseum. > > I've done everything I can think of. I've diddled all available BIOS > settings (this is not an enthusiast board; it has only a limited number > of settings); stopped the kernel from loading just about any > non-essential module; preventing many services from starting. No gdm, no > X, no Intel i915 driver, no acpid, no alsa, no pulseaudio, yada yada yada. > > About the only things I haven't tried are (1) trying Charles' suggestion > of playing with cpusets, mostly because I don't understand them well > enough yet to trust myself, (2) ripping out some more modules that > relate to sound (with names snd*; alsa and pulseaudio stuff is already > gone), mostly because I'm not sure who's loading them, and (3) redoing > all this with a 32-bit Debian Wheezy, mostly because getting Debian > Wheezy systems into this machine is a bore (the Wheezy installer is > broken somewhere in the disk partitioning process and why should I be > the one to fix it when others have been complaining forever). > > Now, my question. > > I'm wondering if my results are intrinsic to the Atom architecture or > specific to the ASUS BIOS. > > Has anyone with a different Atom board, preferably an Intel-branded > board, loaded and tested Wheezy with Linux-RT and LinuxCNC? If so, > what's your experience? > > Regards, > Kent > > > > > > ------------------------------------------------------------------------------ > Got visibility? > Most devs has no idea what their production app looks like. > Find out how fast your code is with AppDynamics Lite. > http://ad.doubleclick.net/clk;262219671;13503038;y? > http://info.appdynamics.com/FreeJavaPerformanceDownload.html > _______________________________________________ > Emc-developers mailing list > Emc-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-developers > ------------------------------------------------------------------------------ Got visibility? Most devs has no idea what their production app looks like. Find out how fast your code is with AppDynamics Lite. http://ad.doubleclick.net/clk;262219671;13503038;y? http://info.appdynamics.com/FreeJavaPerformanceDownload.html _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
