ISO install of LinuxCNC on Debian 8 & Mint LMDE 2

Interzen
There are a few things you can try for latency issues. What I describe here works for Intel processors 32-bit or 64-bit install, so if you are using a AMD this will not work.
First if you used ISO, grub-customizer was also installed which will make a few thing a little easier. Open grub-costomizer you will find it in Menu->Administration->Grub Costomizer.
The opening screen will be on the List Configuration Tab
right click on the kernel you are working with, make sure not to choose (systemd) or (recovery mode)
select Edit
new window will open select Source tab
Now look for the line that looks something like this example, Your kernel will have a different name that this "3.2.0-0.bpo.4-rt-amd64"

linux linux /vmlinuz-3.2.0-0.bpo.4-rt-amd64 root=/dev/mapper/mint--vg-root ro quiet splash $vt_handoff

You can add kernel boot options here, I suggest the following options

lapic noxsave -original paramters- intel_idle.max_cstate=0 processor.max_cstate=0 isolcpus=1

which would be added into the line after quiet splash and before $vt_handoff for this example as bellow shows.

linux linux /vmlinuz-3.2.0-0.bpo.4-rt-amd64 root=/dev/mapper/mint--vg-root ro quiet splash lapic noxsave -original paramters- intel_idle.max_cstate=0 processor.max_cstate=0 isolcpus=1 $vt_handoff

The above would be for a 2 core processor the option isolcpus=1 would be different for other multi core processors
isolcpus=2,3 <would be used for a 4 core processor
isolcpus=3,4,5 <would be used for a 6 core processor
isolcpus=4,5,6,7 <would be used for a 8 core processor

The idea behind this is to isolate realtime activity to the fist set of cores which improves latency.

NOW MAKE A NOTE: The above could all have been done on the General Settings tab which would change kernel parameters for all loaded kernels. But if any changes that were made caused boot failure, all kernel boot choices would fail at boot. Doing as I described above, only changes it for the kernel parameters for the kernel being edited. Which still leaves the option to boot into another kernel such as the default kernel that was loaded at OS install. This would allow to re-edit any bad parameter choices made previously in the kernel that was edited.


If you are using a dual core you can also follow the directions here which will gain a little more:

forum.linuxcnc.org/forum/18-computer/259...s?limitstart=0#27492



Now for one more thing turning off SMI but you have to be careful, please heed the warning at the following link:

forum.linuxcnc.org/forum/18-computer/259...s?limitstart=0#27492

I will tell you how to do this but you do at your own risk, open terminal

git clone git://git.kiszka.org/smictrl.git && cd smictrl
git clone git://github.com/zultron/smictrl-deb.git debian
sudo apt-get install libpci-dev
fakeroot dpkg-buildpackage -uc -us
sudo dpkg -i ../smictrl_*.deb

# To find out the details about your Intel chipset

sudo smictrl

# To make smictrl load at every boot

sudo gedit /etc/rc.local

# Edit add the following before the line exit 0

smictrl -s 0

# save

sudo reboot

This option needs to be monitored with psensor, ( watching CPU temp) and System Monitor,(set on System Load tab) making sure your system can handle this.
To install psensor open terminal

sudo apt-get install psensor

To install a System Monitor if not a Menu item:

sudo apt-get install ksysguard

With monitoring you will notice the effects of isolcpus CPU load will be high on first group of cores just make sure temp does not get to high

ANOTHER NOTE: Doing latency test I prefer to use latency-plot form terminal it show initial spike in system then settles and you maybe be able to isolate a hardware issue using latency-plot.
Also latency-histogram from terminal for a extended time latency test. If you are just interested in servo thread only invoke in terminal with latency-histogram --no base

If you carry out all of the above you will see a great latency improvement

Good Luck
Tim

Big John T wrote:

I think you need a 64 bit processor to use a 64 bit kernel

If a computer's processor has more that one core, (multi-core) a 32bit or 64-bit Operating system can be installed

Tim

Tim,

Where can I get glade? Only the latest is available and doesn't support editing the panels.

I need Version 3.8 I think it was. I can't remember now. I tried looking for a deb for it, but could only find source without instructions [googled it]. I'm sure I could figure it out, but wanted to know if you knew something easier.

cncnoob1979 wrote:

I need Version 3.8 I think it was. I can't remember now. I tried looking for a deb for it,

try:

packages.debian.org/jessie/glade

To the right on page you can check each repository by clicking

[ squeeze ] [ wheezy ] [ jessie ] [ stretch ] [ sid ] [ experimental ]

At the bottom of page pick "arch" that you need, you will be redirected to page with list of mirrors to download from pick one then download package.

After download go to download folder right click choose open terminal here

sudo gdebi -n <name.deb>

When you are trying to find a package google

debian <pakage name & version>

Tim

Please be carefull, as glade 3.18 will not work with gtk2 and therefor not with gladevcp nor the GUI's based on that. So you will not be able to edit gmoccapy or gscreen files!

and do not use 3.8.0 as it is buggy and will terminate with a segmentation fault, better get from source 3.8.5

Norbert

Thank you, Tim and newbynobi,

Ill try to find that when I get back from work.

I have been playing with this with mixed results. I first installed LMDE 64bit MATE and had things running but had terrible latency, lowest I could get was 50, worst was 180. So I blew that away and installed LMDE 32bit MATE with the default rt10mah+ kernel. All went well until I tried to run the latency tests which would not do so. Am just try to get the rtai kernel installed at the moment to see if I can get things going again then it will be testing latency...

RTAI kernel works better, now to get the latency down below 62. Stock Jessie Linuxcnc install on this machine is around 4 to 5 so this one will need a little work me thinks

Wowsa! Installed an old nvidia card into 64bit LMDE-2 and the latency dropped to 5.8. Jumps a little with glxgears etc but this machine is purely for CNC so really the only thing that will be running with be LCNC. Alot happier this time around!