On Saturday, March 31, 2012 01:32:39 PM Kirk Wallace did opine: > On Sat, 2012-03-31 at 08:00 +0200, Alwyn McLeod wrote: > > When I run the latency test, I get Base thread jitter of 932659. In > > the config file the max. is set at 50,000. > > > > When I load EMC2 I get a message "Unexpected real time delay: check > > dmesg for details' as well " RTAPI: ERROR:Unexpected realtime delay > > on task 1. This message will only display once per session. Run > > latency test and resolve before continuing. > > > > Being a novice as far as Ubuntu is concerned, I am at a loss as to how > > I can resolve these issues. Any assistance will be appreciated. > > The jitter you measured is too high, so you'll need to make some > configuration changes to make it better. If your PC where sitting in > front of me, I would first check on what slots it has, the processor > type and chipset, what video port is being used as well as the monitor. > This would give me an idea of what changes can be made to keep the video > system from interfering with latency. Also I would watch the latency > test for a while to see when the really bad numbers come up. If the > numbers jump right a way, my guess is the video driver, if some event > like a disk access or plugging in or accessing a USB device, maybe a > related BIOS setting may be needed. If it happens and repeats after a > couple of minutes, it might be the SMI issue mentioned in the trouble > shooting section on the wiki. When the latency numbers start getting > pretty good from the changes you have made, it would be best to run the > test over night to make sure something else that operates on a long time > base doesn't slip through. > > Without knowing all of the above, my most common solution tends to be > getting the xorg.conf file settings to work. On a new install, this file > doesn't exist. So one will need to be made. If you have an xorg.conf > file, make a copy of it so you can reuse it if needed. > > I usually start a terminal window (from the Desktop; Applications / > Accessories / Terminal), type on the command line "sudo > gedit /etc/X11/xorg.conf". This will give you root privileges so you can > edit a system file, then gEdit will create the new file and you can fill > in what is needed. Usually I add something similar to: > ~~~~~~~~~~~~~ > Section "Device" > Identifier "Configured Video Device" > # Driver "nvidia" > Driver "vesa" > EndSection This does generally help considerably. Unforch, the vesa driver, specs written back in 4/3 CRT display days, has not kept pace with the available monitors, which are all only available in 16/9 formats, at least here in the states, so while the vesa driver will work at its maximum 1024x768 resolution, on modern monitors you no longer have 'square pixels, meaning round objects aren't round, but oval.
Occasionally a 3rd party driver will work well. On the box I just retired because the motherboard caps were failing, I had an ATI 9200SE card in it, and switching to the ati driver as above, which in turn loads the correct ATI driver for that card, I was amazed to find that latencies had not taken a big hit (unlike the nvidia drivers which are truly horrible to the latency figures) and that I once again had square pixels on a 16/9 monitor. In fact it worked amazingly well. But as in all things video vs linuxcnc, YMMV. > Section "Monitor" > Identifier "Configured Monitor" > Option "DPMS" > Horizsync 30-66 > Vertrefresh 50-130 > EndSection > > Section "Screen" > Identifier "Default Screen" > Monitor "Configured Monitor" > Device "Configured Video Device" > Defaultdepth 24 > SubSection "Display" > Viewport 0 0 > Depth 24 > Modes "1280x1024" > EndSubSection > EndSection > > Section "ServerLayout" > Identifier "Default Layout" > screen "Default Screen" > EndSection > ~~~~~~~~~~~~~~ > > The # comments out the current video driver if this line exists, then I > load a generic driver (vesa) that plays well with latency. Sometimes > there is an open source version of a proprietary driver, which can work > well and have more features than vesa. The nouveau driver seems to be working very well when it works, but isn't 100% bulletproof _yet_. I just ran it here for a couple weeks. Text rendering is better than nvidia, but I had several outright crashes, usually the reboot screen being the first hint that things have gone face down in the oatmeal. No traces in the logs, just the normal reboot sequence. > The monitor section lets the computer know what frequencies and > resolutions are valid for the monitor. My equipment tends to be very old > and Xorg has a hard time getting the settings on its own. One thing I do > first is to bring up System / Preferences / Monitors and see if the > monitor is recognized and the proper resolutions listed. If not, I add > the Monitor and Screen sections to xorg.conf. If you add the monitor > data, it is very important you use the actual data that matches the > make, model and version of your monitor. Setting these wrong can make > you monitor unreadable or go blank, and for a Linux novice can be very > hard to get out of gracefully. By the way, if this happens, Alt F1 may > get you to a terminal session. If Xorg does get some of these settings > correctly, then you can leave those parts out. Getting this sorted out > can take hours and a lot of rebooting. Oh, and when you save the new > settings, just log out and back in (use the power icon and log out > instead of power off) in order to activate the new settings or reboot. > > If the latency problem is not video related, you may need to study the > troubleshooting and related sections in the wiki and other > documentation. > > Don't be afraid to ask questions, good luck. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> Today when a man gets married he gets a home, a housekeeper, a cook, a cheering squad and another paycheck. When a woman marries, she gets a boarder. ------------------------------------------------------------------------------ This SF email is sponsosred by: Try Windows Azure free for 90 days Click Here http://p.sf.net/sfu/sfd2d-msazure _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
