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LinuxCNC
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Installing LinuxCNC
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ISO install of LinuxCNC on Debian 8 & Mint LMDE 2
ISO install of LinuxCNC on Debian 8 & Mint LMDE 2
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Thank you received: 0
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12 Feb 2016 17:18 #70044
by Interzen
Thanks for the update racedirector,
That might give me clues where to look.
I have not been able to get the latency down below 60-80 on my machine runnung debian 8.3 64bit on an intel j1800 based MB. I found and fixed a network driver error, PC-speaker driver error, adjusted bios settings, checked that the rt kernel was running, set to one core (isolcpus=1), all with little improvement. I have also started playing with smi but I don't think my answer lies there. Based on your experience I should try running headless next and see if that helps.
I have a drive configured with the stock Debian Wheezy linuxcnc distribution that gets 5 to 6 latency without stress and up to 14 while running 5xglxgears+pandora+youtube+package updates, all with the default bios settings and on-board video.
I did capture one error msg during the install of tjmarch's linuxcnc.iso.
Right at the start after answering yes to installing the RT kernel:
Do you want to install Rt-preempt Kernel (y/n)?
answer no to install sim mode
sed: can't read /etc/apt/sources.list.d/linuxcnc.list: No such file or directory
Executing: gpg --ignore-time-conflict --no-options --no-default- (...ETC)
I have scanned the rest of the command session and and it seems to go fine from there.
I will probably just stick with the official linuxcnc pre-build for now if it is video causing the problem. This MB has only pcie and mpcie and I don't have any compatible video cards plus the thin m-itx case I put it in has no room. I am really happy with it under wheezy straight out of the box and need to be spending this time finishing my machine.
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14 Feb 2016 03:29 #70096
by cncnoob1979
Are you using software stepgen?
If not, you do not need to go down so low on latency. It seems everyone is trying to get such a very low latency that it distracts from the fact that unless you are using software stepgen you do not need to worry so much about latency, within reason of course. Also, from my research it seems that software stepgen is fairly stable with higher latency than you reported.
just my 2Cents
I'm around 15-30 if I use every method of reducing my latency, however my computer slows to a crawl. So i decided not to worry so much about latency of my PC. I'm pretty stable around 45-50 with occasional spikes, but I'm using MESA hardware and I'm not concerned with it.
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18 Feb 2016 20:41 #70351
by islander261
Hello
Has anyone tried this using this install with an ethernet connection to a Mesa 7i76E card? I have an old Dell SFF Optiplex 745 with onboard Broadcom NIC, will this work or do I need a separate PCI card with a Realtek chip?
John
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18 Feb 2016 23:17 #70356
by PCW
My experience with Broadcom is that they dont work well for real time YMMV
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20 Feb 2016 22:02 #70413
by islander261
I have install LDME 2 64 bit OS on my Dell SFF Optiplex 745 box. Using the ISO I installed LCNC and the Preempt-RT kernel. Everything seems to work but the latency seems quite high. Please see attached image. I tried to use the tricks shown in this post
www.forum.linuxcnc.org/forum/9-installin...mde-2?start=10#69182 but couldn't get the sim control to install. I am very new to using Linux and don't really know what I am doing.
Here is the results of lspci if it helps:
jd@plasma1 ~ $ lspci
00:00.0 Host bridge: Intel Corporation 82Q963/Q965 Memory Controller Hub (rev 02)
00:02.0 VGA compatible controller: Intel Corporation 82Q963/Q965 Integrated Graphics Controller (rev 02)
00:02.1 Display controller: Intel Corporation 82Q963/Q965 Integrated Graphics Controller (rev 02)
00:1a.0 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #4 (rev 02)
00:1a.1 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #5 (rev 02)
00:1a.7 USB controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #2 (rev 02)
00:1b.0 Audio device: Intel Corporation 82801H (ICH8 Family) HD Audio Controller (rev 02)
00:1c.0 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 1 (rev 02)
00:1c.4 PCI bridge: Intel Corporation 82801H (ICH8 Family) PCI Express Port 5 (rev 02)
00:1d.0 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #1 (rev 02)
00:1d.1 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #2 (rev 02)
00:1d.2 USB controller: Intel Corporation 82801H (ICH8 Family) USB UHCI Controller #3 (rev 02)
00:1d.7 USB controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #1 (rev 02)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev f2)
00:1f.0 ISA bridge: Intel Corporation 82801HB/HR (ICH8/R) LPC Interface Controller (rev 02)
00:1f.2 IDE interface: Intel Corporation 82801H (ICH8 Family) 4 port SATA Controller [IDE mode] (rev 02)
00:1f.3 SMBus: Intel Corporation 82801H (ICH8 Family) SMBus Controller (rev 02)
00:1f.5 IDE interface: Intel Corporation 82801HR/HO/HH (ICH8R/DO/DH) 2 port SATA Controller [IDE mode] (rev 02)
02:00.0 Ethernet controller: Broadcom Corporation NetXtreme BCM5754 Gigabit Ethernet PCI Express (rev 02)
jd@plasma1 ~ $
I want to use this box with a Mesa 7i76E if possible, is the latency too high? Any suggestions before I start looking around for another box?
John
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20 Feb 2016 22:24 - 20 Feb 2016 22:35 #70414
by tjmarch
You only ran latency-histogram for 24 min not long enough to tell anything. Latency plot did not look to bad. You need to invest some time and read the included documentation that was installed. The best way to learn is to do a little resurch then when you do not understand something ask. I have given you a great start with the ISO but you have to attempt to help yourself. What trouble did you have with post on lowering latency there is nothing about sim control. Did you mean something else like
SMI control.
Tim
Last edit: 20 Feb 2016 22:35 by
tjmarch.
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20 Feb 2016 22:43 #70416
by PCW
That latency is probably OK but note that the Broadcom Ethernet is probably not
usable for the real time Ethernet connection (Intel and Realtek are known to be OK)
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26 Feb 2016 23:11 #70688
by islander261
Hello
I have gone back and did a fair amount of testing with little improvement to show for it. I was successful in getting the SMI control software installed and run. I also experimented with using isolcpus again with little change in latency. I then installed a video card so the onboard video wasn't being used again with little change in latency.
The one think that stood out is that when using smictrl as instructed when I shut down the machine using the menu button the power does not shut off, I have to manually push the power button on the box after the black Linux Mint splash screen pops up.
I understand that I need to use an Intel or Realtek chip base NIC for real time control of a Mesa 7i76E card. Is there a preferred chip series to use or avoid?
John
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27 Feb 2016 00:35 - 27 Feb 2016 00:37 #70691
by PCW
Any Intel or Realtek NIC that fits should b e OK
Isolcpus is typically a bad idea with Preempt-RT and hm2-eth (it just slows everything down)
You can probably get some improvement by using a core 2 DUO with more cache
(a E8500 has 3x the cache size of your E6400 and is about $15.00 on ebay)
Cache size makes a big difference (how much of the real time stuff stays in cache has a big effect on latency)
All this said, unless you dont meet the 1 ms thread time deadline (and so get real time errors)
the latency is pretty much immaterial
Much too much time is wasted improving latency for no real benefit, especially if you dont need software step generation
Last edit: 27 Feb 2016 00:37 by
PCW.
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27 Feb 2016 23:22 #70735
by jtc
Hi.
when I tried to install linuxcnc on LMDE2 using the iso, I'm only able to install the kernel. I got errors like these:
Err http://buildbot.linuxcnc.org jessie/2.7-rtpreempt Sources
403 Forbidden
Err http://buildbot.linuxcnc.org jessie/2.7-rtpreempt amd64 Packages
403 Forbidden
Ign http://linuxcnc.org jessie/base Translation-en
Err http://buildbot.linuxcnc.org jessie/2.7-rtpreempt i386 Packages
403 Forbidden
Ign http://packages.linuxmint.com betsy/import Translation-en_GB
Ign http://buildbot.linuxcnc.org jessie/2.7-rtpreempt Translation-en_GB
Ign http://packages.linuxmint.com betsy/import Translation-en
Ign http://packages.linuxmint.com betsy/main Translation-en_GB
Ign http://packages.linuxmint.com betsy/main Translation-en
Ign http://packages.linuxmint.com betsy/upstream Translation-en_GB
Ign http://buildbot.linuxcnc.org jessie/2.7-rtpreempt Translation-en
Ign http://packages.linuxmint.com betsy/upstream Translation-en
Fetched 140 kB in 16s (8,471 B/s)
W: Failed to fetch http://buildbot.linuxcnc.org/dists/jessie/2.7-rtpreempt/source/Sources 403 Forbidden
W: Failed to fetch http://buildbot.linuxcnc.org/dists/jessie/2.7-rtpreempt/binary-amd64/Packages 403 Forbidden
W: Failed to fetch http://buildbot.linuxcnc.org/dists/jessie/2.7-rtpreempt/binary-i386/Packages 403 Forbidden
E: Some index files failed to download. They have been ignored, or old ones used instead.
anyway, following the online instructions to install on debian jessie I manage to install linuxcnc.
there is any way to install linuxcnc run in place with this kernel ?
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LinuxCNC
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Installing LinuxCNC
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ISO install of LinuxCNC on Debian 8 & Mint LMDE 2
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