Results of latency test, list of computers tested for use with LinuxCNC

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09 Sep 2020 20:26 - 09 Sep 2020 20:26 #181503 by seuchato
Himarc3D

What were the latencies you got with mint?
tommylight already pointed out that debian is "a bit better" on latencies than mint. I observed the same when running the test on both mint (19.3 in my case) and debian buster (10.4 to 10.5) on the same machine.

Greez
chris
Last edit: 09 Sep 2020 20:26 by seuchato. Reason: typos
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09 Sep 2020 21:05 #181509 by tommylight
Also Mint 19.3 XFCE is a bit better than Mint 19.3 Mate.
On two older laptops i can not get usable latency for a Mesa ethernet board with Preempt-RT and Mate, but i can get very usable latency with XFCE and same kernel.
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10 Sep 2020 04:36 #181550 by CORBETT

tommylight wrote: I do have 3 of the ASUS A270Z PRO MB in use, but not for machines ! :) They are busy mining ethereum.
.


Tom...
I had to go check that out and was some interesting reading about Ethereum. I had never really read about how it worked until seeing your post and had to go see what it was about.


Robert
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10 Sep 2020 08:08 #181577 by tommylight
Feel free to start a topic about crypto in the "off topic" section so we can have a go at it, it is very good stuff but humans are humans so on one side they left it unused and on the other side they are doing everything to make it even more useless due to lack of ideas.

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10 Sep 2020 22:38 #181685 by Himarc3D

seuchato wrote: Himarc3D

What were the latencies you got with mint?
tommylight already pointed out that debian is "a bit better" on latencies than mint. I observed the same when running the test on both mint (19.3 in my case) and debian buster (10.4 to 10.5) on the same machine.

Greez
chris


Sorry for late reply, im busy working!

The difference was minimal, i just let Debian because was the last in the tests.
I can test again this weekend and save the data, ill check the Mint with 2.8 release. Ill check next Thursday using p/2 mouse and keyboard too if make anu difference for my setup.

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11 Sep 2020 00:20 #181693 by BeagleBrainz
Chasing the last nano second of latency is not really worth it, especially with Mesa hardware.
The Mint 19.3 ISO with 2.8 should not be any different to the Mint 19.2 ISO with 2.8~pre as the both use the same 4.x series kernel (I found this to be the best). Exactly the same kernel actually from the same package. The Linuxcnc packages are compiled on a 19.2 box.
If there are latency issues and you want to use the Parallel Port there is a RTAI kernel that Andy is working on.
Reducing the amount of USB hardware can help with latency, one thing I do when machining is to turn off wifi.
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11 Sep 2020 08:52 - 11 Sep 2020 09:09 #181738 by Himarc3D

BeagleBrainz wrote: Chasing the last nano second of latency is not really worth it, especially with Mesa hardware.
The Mint 19.3 ISO with 2.8 should not be any different to the Mint 19.2 ISO with 2.8~pre as the both use the same 4.x series kernel (I found this to be the best). Exactly the same kernel actually from the same package. The Linuxcnc packages are compiled on a 19.2 box.
If there are latency issues and you want to use the Parallel Port there is a RTAI kernel that Andy is working on.
Reducing the amount of USB hardware can help with latency, one thing I do when machining is to turn off wifi.

Thank you for advice but in my case i just will install it because i read somewhere from Tommy about things sometimes dont work like they are supposed to be using Debian, and many veterans here at forum use Mint, so ill follow you guys!
My minipc don’t have parallel port or expansion slot...actually i don’t recommended this minipc, get very hot and no way to use inside cabinet (passive here big cabinet, maybe i test positive pressure using welder vest like vortex ilask my friend to use his vortex for a while), if i swap dsub to hmi or vice versa the desktop become clean, after clean install of OS using any GUI i get clean desktop too, just right mouse click work and keyboard to invoke terminal and configure primary monitor.
The bios I disabled many things, include sound but the kernel loaded the module, I blacklisted sound, Bluetooth, wifi, everything I don’t need
Last edit: 11 Sep 2020 09:09 by Himarc3D.

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18 Sep 2020 04:11 - 19 Oct 2020 07:15 #182603 by seuchato
Here is the result of a desktop version of a dell 980 withj a 4core i5 750 cpu, all cores enabled. This machine has four expansion slots, 1 pcix 1 pci and 2 pci express. One is used for an ATI GPU ([AMD/ATI] RV710 [Radeon HD 4550]). When running with base period 25`000, I got real time delays, thus this test is with a base period of 50`000.

Looking at the promising results of this 4 core i5, I will retest the 980 here (two core i5 cpu) and compare them.

LinuxCNC pc tests, version 20200905, started 15.09.2020 11:08:57
********************************************************************************
General info:
Dell Inc.,  OptiPlex 980                 
Bios version A18, dated 02/27/2018
Chipset: Intel Corporation 5 Series/3400 Series 
Harddisk is non-rotational, ie. SSD
The amount of swap currently used is 0
================================================================================
CPU related data:
model name      : Intel(R) Core(TM) i5 CPU         750  @ 2.67GHz
cpu cores       : 4
stepping        : 5
cache size      : 8192 KB
================================================================================
RAM related data:
Maximum Capacity: 16 GB
Size: 2048 MB
Size: 2048 MB
Size: 2048 MB
Size: 2048 MB
================================================================================
GPU related data:
product: RV710 [Radeon HD 4550]
configuration: driver=radeon latency=0
================================================================================
Parallel port related data:
number of parallel ports is 1
parport0: PC-style at 0x378 (0x778), irq 7 [PCSPP,TRISTATE,EPP]
================================================================================
Os related data:
PRETTY_NAME="Debian GNU/Linux 10 (buster)"
Desktop: KDE, Session: 
================================================================================
Kernel related data:
Kernel 4.19.0-10-rt-amd64
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash idle=poll"
Cpu idle driver: none
================================================================================
Kernel modules data:
Check if pcspkr is loaded: No, good!
Check if snd modules are loaded: No, good!
================================================================================
Keyboard & Mouse related data:
Number of mice: 1
Mouse 0 : Logitech MX Anywhere 2
Mice  attached to USB:
Keyboards attached to USB:
MosArt Semiconductor Corp. Defender Office Keyboard (K7310) S Zodiak KM-9010
LinuxCNC related data:
LinuxCNC version is: 2.9.0~pre0.2800.g470fce12e
================================================================================
Preparing for latency test:
Started glxgears No. 1
Started glxgears No. 2
Started glxgears No. 3
Started glxgears No. 4
Started glxgears No. 5
..........
Started firefox with 'https://vimeo.com/150574260' 
================================================================================
Command for latency test is:
su ck -c  "latency-histogram --bbinsize 1000 --base 50000 --sbinsize 1000 --nox 2>&1 | tee -a 1600160922.lat &"

Latency testing loop started Di Sep 15 11:09:11 CEST 2020, 
should end after Di Sep 15 13:09:11 CEST 2020

================================================================================
Swap useage: prerun: 0, running: 0

================================================================================
CPU core temperatures:
Core 0: Tmin: 53.0°C, TMax: 64.0°C, (high = +83.0°C, crit = +99.0°C)
Core 1: Tmin: 54.0°C, TMax: 64.0°C, (high = +83.0°C, crit = +99.0°C)
Core 2: Tmin: 55.0°C, TMax: 65.0°C, (high = +83.0°C, crit = +99.0°C)
Core 3: Tmin: 54.0°C, TMax: 64.0°C, (high = +83.0°C, crit = +99.0°C)
================================================================================
last latency data is as follows:.
 7204 secs   base min: -18.400 uS max:  19.400 uS sdev:   0.900 uS
 7204 secs  servo min: -11.900 uS max:  14.200 uS sdev:   1.600 uS

Greez
chris

PS: I will probably later add here in this post the very bios settings used

Edit: 19. Oct. 2020: Bios Settings are as follows, I only write up what I changed from defaults:
  • General
    • Boot sequence: Excluded "USB Floppy Drive" and "Onboard Network Controller"
    • Drives
    • "Diskette Drive" disabled
    • "SATA Operation": "RAID Autodetect /AHCI"
    • "SMART Reporting": enabled
  • System Configuration
    • "Parallel Port": EPP
    • "Miscellaneous Devices": disbled "Audio", "Opütiplex ON Reader" and "WiFi NIC Slot"
  • Performance
    • "Hyper-Threding Technology": disabled
    • "Intel(R) Turbo Boost Technology": disabled
    • "Intel(R) SpeedStep(TM)": disabled
    • "C States Control": disabled
  • Virtualization Support
    • "Virtualization": disabled
    • "VT for Direct I/O": disabled
  • Power Managment
    • "Low Power Mode": disabled
    • "Suspend Mode": S3 (there is no option to disable it completely)
Last edit: 19 Oct 2020 07:15 by seuchato. Reason: Added BIOS Settings
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18 Sep 2020 04:19 #182604 by seuchato

BeagleBrainz wrote: Chasing the last nano second of latency is not really worth it, ...


100% true

BeagleBrainz wrote: ... 4.x series kernel (I found this to be the best).


Same conclusion here: 4x kernels are the best for the time being-

Greez
chris

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18 Sep 2020 04:29 #182605 by BeagleBrainz
Have 2 kernels you might want to give a go. These are the ones used on the Mint ISOs. The header & libc-dev packages are in the same dirs as linux-image-xxx.
The -rt46 has efi=runtime embedded in the kernel image but should not affect non UEFI systems.

cnc.beaglebrainz.net/mintcnc/pool/2.8-rt...t44-lcnc-1_amd64.deb

cnc.beaglebrainz.net/mintcnc/pool/2.8-rt...t46-lcnc-1_amd64.deb
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