Laptop with low latency for use with Mesa Ethernet boards

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17 Jun 2019 19:33 - 17 Jun 2019 20:05 #137150 by tommylight
Will edit this later and add link to a video, tablet is not behaving!
Back!
Here is the link to the video, notice the Nvidia driver manager in the task bar, they are disabled for the test as it will mess up the latency a bit.


This is a test for an
Acer Aspire 5742 series
model no.PEW71 runing
Linuxcnc 2.9 on Linux mint 19.1 with 4.16.12-rt5-kona-rt kernel,
Mesa 7i92 attached through a cheap gigabit switch, servo thread is at 1ms and there are no latency issues.
It's been ruining for nearly a week wired directly to Mesa 7i92, no errors, even at heavy use of youtube and file copy. Intel core i5 M480 processor. BIOS is poor so not much to disable. Warning ! This is a proof of viability, not to be used on machines wired through switch, never. Direct connection of Mesa 7i92 ( or 7i96 or 7i76E or 7i80 ) to the PC Ethernet port is obligatory. Also as information on a good laptop with very low latency that is also very cheap. Not easy to find them........ this one was brought to me, gave 65 euro for it, although it is in pitiful condition visually.
FYI, the above mentioned Linux kernel can be found and downloaded in the debian packages site and it has much better latency than the ones i compiled following the tutorials on this forum, on some computers, not all. On some new computers it has no big difference in latency.
Last edit: 17 Jun 2019 20:05 by tommylight. Reason: Tablet went out.
The following user(s) said Thank You: phillc54

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18 Jun 2019 05:31 #137171 by pl7i92
i use on all CNC in school a Fujitsu Siemens S7110 Notebook at a 7i92
workes gread
ok i did not check out the max speed as i only use 200k BOB
no direct connect
but i can go well over ACC 1200mm/s²
with a 10m/min Vel
at 100scale
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18 Jun 2019 13:34 #137184 by tommylight
You should also do a small test so others can have info on what actually works with Mesa ethernet cards.

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18 Jun 2019 15:27 #137197 by pl7i92
as of all new videos i posted the 7i92 is so universe now as >30 Configs are available
and my knowledge is not that good to do tastings
even the hardware i got to do this is not reliable on testing

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24 Sep 2019 12:10 #146057 by tommylight
Gave it a heavy gcode file, set the maximum velocity to 19mm/m and left it for 4 days, it is still running and has another day and a half to go to the finish. Still no errors, no matter what i throw at it.
Not very useful info as they are hard to find.

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14 Oct 2019 10:35 #147864 by ross_dev
Hi tommylight

This is super interesting work, thank you!
  1. I am curious, does the use of the mesa card mean that latency becomes less of an issue? If so what are the acceptable jitter limits using this setup?

  2. I note from the standard installation procedure that usually you create the debian wheezy iso and install that way. You mentioned using mint here, is this using a dev build or is there an alternate way of installing LCNC into other OS?

  3. Also please could you expand on this line a little:

Warning ! This is a proof of viability, not to be used on machines wired through switch, never.


What do you mean by a switch, and why is it a particular issue?

My hope is to use standard laptops we have available as a control PC, wired via 7i92M / 7i74 to a set of STMBL drives.

Cheers
RD

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14 Oct 2019 11:13 #147865 by tommylight

  1. I am curious, does the use of the mesa card mean that latency becomes less of an issue? If so what are the acceptable jitter limits using this setup?

Yes it does, that particular laptop has a latency of 100 to 120K, and it never fails, even after several days of constantly on and me using it online. I have some other laptops with latency of 200 to 300K and they get disconnected after 5 to 30 minutes of use as the tend to have excursions of over 2M !

ross_dev wrote:

  • I note from the standard installation procedure that usually you create the debian wheezy iso and install that way. You mentioned using mint here, is this using a dev build or is there an alternate way of installing LCNC into other OS?
  • No need to create anything, it is ready made, it needs just to be written to a USB and booted from it. Same goes for the Stretch version, this is the version to use with Mesa ethernet boards.
    I use Mint and just install a precompiled kernel and Linuxcnc.

    ross_dev wrote:

  • Also please could you expand on this line a little:
  • [/ol]

    Warning ! This is a proof of viability, not to be used on machines wired through switch, never.

    What do you mean by a switch, and why is it a particular issue?

    Swith or router or hub, are equipment to connect several computer on the network.
    Mesa ethernet cards should never be connected through any of the above, they should be ALWYS connected directly to the control PC.

    Download the stretch version, write it to a USB, boot the laptop with it and run latency test while doing other things on it, like watch youtube and change to full screen several times, copy some big files from internal HDD to internal HDD and to USB, run glxgears from a terminal and also maximise and minimise several times, leave it on for a day or two, then check the latency.
    Anything under 100 to 150K should be usable, but the only real test is to attach the mesa board to it and check if it looses the connection, while using the laptop for other things mentioned above.

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    14 Oct 2019 12:03 #147866 by ross_dev
    Ah great thats fantastic! I have booted one of our laptops into stretch and running the latency tool now. Biggest spike so far with glxgears, running internet and opening / closing things is 160K for servo thread, so just above the upper range of the limit. Do you think this will be a no go?

    Servo thread: 164K
    Base thread: 230K

    Hopefully testing with some hardware will prove it out!
    Cheers

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    14 Oct 2019 12:11 #147867 by tommylight
    That might still be usable, no way of knowing for sure untill you actually connect a Mesa board.
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    22 Oct 2019 22:09 #148561 by renatofmpinheiro
    Hi Tommy,

    Installed the linuxcnc Debian 9 Stretch on my laptop HP dv6 6080ep and got the follow results:
    https://ibb.co/cXHZbXd

    I put the test running for about 2 hours with a movie playing.

    How I can know if my laptop is good enough to use with a 7I92?

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