7i80 and 7i77

With the cyclictest I got average latency of about 6us and maximum of about 900us so it seem to be showing the same thing as the latency test.

Heres hardware I have tested that works OK with Preemt-RT and Ethernet at 1 KHz servo thread:

Gigabyte H81-D3 with G3258 CPU (good to 3 KHz)
ASRock H97M Pro 4 with G3258 CPU (good to 4 KHz)
GIGABYTE GA-J1800N-D2H
BIOSTAR A68N-5000
HP Stream Mini (need to disable on board Broadcom WIFI)
Intel D525 (marginal speed wise)
HP DC7800 with core duo E8500 CPU (good to 2.5 KHz)
Dell 6420E (Laptop) you cannot change power modes while running, otherwise OK
Intel BOXDG41AN mini ITX core duo E2180

What specific MB do you have?

I do not now what kind it is, it doesnt say but the chipset should be Intel® NM70 Express Chipset

Trying a reinstall to see where it goes wrong
A fresh install of the Debian wheezy distro gives an average of 11000ns and ocasional spike of 235000ns every minute or so, just like before.
The GRUB edit lowers it to 1800ns but still the big spike.

After disabling "acpi sleep state" and "hibernation I now got one spike of 49000ns after a minute or so and then a steady max of 3000ns for the next ten minutes

Upgraded to 2.7, latency remains the same but argg, now I got a 220000ns spike again, and again, seem like 2.7 did something not so good for my motherboard, but still only ocasional (and regular I think) spikes, not like the 1000000ns I had before.

Sudo apt-get update and sudo apt-get dist-upgrade. Still the same

After the remaining steps of installing the RT kernel though its crazy again and I have about 650000ns as soon as I click the mouse.

Any thoughts?

andypugh wrote:

jeeybee wrote:

Upgraded to 2.7, latency remains the same but argg, now I got a 220000ns spike again, and again, seem like 2.7 did something not so good for my motherboard

LinuxCNC isn't even running when you do the Latency test, so it has _nothing_ to do with the LinuxCNC version.

When you say "upgraded to 2.7" did you also change the OS version?

It looks like your best bet is Debian Wheezy + LinuxCNC 2.7, assuming that the Wheezy install was RT-PREEMPT and not RTAI?

This is what I did:

4.1.1. Setting apt sources
• Open the Software Sources window. The process for doing this differs slightly on the three supported platforms:
o Debian Wheezy:
 Click on Applications Menu, then System, then Synaptic Package Manager.
 In Synaptic, click on the Settings menu, then click Repositories to open the Software Sources window.
• In the Software Sources window, select the Other Software tab.
• Delete or un-check all the old linuxcnc.org entries (leave all non-linuxcnc.org lines as they are).
• Click the Add button and add a new apt line. The line will be slightly different on the different platforms:
Platform apt source line
Debian Wheezy deb linuxcnc.org wheezy base 2.7-rtai


Click Add Source, then Close in the Software Sources window. If it pops up a window informing you that the information about available software is out-of-date, click the Reload button.

Debian Wheezy and Ubuntu Lucid both use the Synaptic Package Manager.
• Open Synaptic using the instructions in Setting apt sources above.
• Click the Reload button.
• Use the Search function to search for linuxcnc.
• Click the check box to mark the new linuxcnc and linuxcnc-doc-* packages for upgrade. The package manager may select a number of additional packages to be installed, to satisfy dependencies that the new linuxcnc package has.
• Click the Apply button, and let your computer install the new package. The old linuxcnc package will be automatically upgraded to the new
• one.


7.1. Installing on Debian Wheezy and Debian Jessie (with Preempt-RT kernel)
The RTAI kernels are available for download from the linuxcnc.org debian archive. The apt source is:
• Debian Wheezy: deb linuxcnc.org wheezy base

• Run sudo apt-get update followed by sudo apt-get dist-upgrade to bring the machine up to date with the latest packages.

Here it was still ok

• Install the Preempt-RT kernel and modules by running: sudo apt-get install linux-image-rt-amd64 or sudo apt-get install linux-image-rt-686-pae.
• Reboot, and make sure you boot into the Preempt-RT kernel. When you log in, verify that uname -v includes PREEMPT and RT.
• Add the LinuxCNC Archive Signing Key to your apt keyring by running sudo apt-key adv --keyserver hkp://keys.gnupg.net --recv-key 8f374fef
• Add a new apt source that looks like this: deb linuxcnc.org/ wheezy base 2.7-uspace or deb linuxcnc.org/ jessie base 2.7-uspace
• Run sudo apt-get update again to fetch the package list from linuxcnc.org.
• Run sudo apt-get install linuxcnc-uspace.
• Machine away!

Here its not

Really big latency spikes tend to be from things like power management or SMI
Are you sure all power management options are disabled in the BIOS?

~Once a minute errors are almost certainly SMI related

PCW wrote:

Really big latency spikes tend to be from things like power management or SMI
Are you sure all power management options are disabled in the BIOS?

~Once a minute errors are almost certainly SMI related

The 1min spikes are second priority

After the Preempt-RT installation I got spikes of 600-700000ns every time I click the mouse and every time I do anyting at all

It may simply be that that particular motherboard/BIOS combination is not usable for real time

Does the stock linuxcnc/wheezy RTAI ISO have poor latency?


Start the latency test running and run glxgears and say a youtube video running for a couple of hours
if the RTAI latency after this is > say 75 usec and you have tried all the BIOS tricks* I would give up on
it


* do you have legacy USB emulation turned on? that can cause troubles every time you use the kb/mouse as can the PC speaker.
hard drive troubles (failing drive) can also cause big latency spikes

It still has the one minute interval smi spikes of 50-250us yes, but when I installed RT PREEMT the latency is constantly around 700us.
Something happends when I install the RT kernel and also if I boot to RTAI it is the same after installing RT.

It may help to turn off legacy for the one minute spikes but it does not help for this.

Could it be that something went wrong with the installation, I remember that the packet manager complained about some duplicates and when I applied the "LinuxCNC Archive Signing Key " I think the terminal said that it did not change.

Edit: here is the message:
W: Duplicate sources.list entry linuxcnc.org/ wheezy/base i386 Packages (/var/lib/apt/lists/linuxcnc.org_dists_wheezy_base_binary-i386_Packages)