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

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4 years 7 months ago #236863 by tommylight
Replied by tommylight on topic Results of latency test, list of computers tested for use with LinuxCNC

Tommy,
Does that mean, you get that error too?
No, i never did, but i know others do, probably some kid safety feature, same thing as in the movies, rated PG13 ! :)

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4 years 7 months ago #238144 by tallerseverino
Replied by tallerseverino on topic Results of latency test, list of computers tested for use with LinuxCNC
Hello to everyone.
I'm new to the forum and to linuxcnc. With the help of the forum, linuxcnc documentation and a little luck I finally did a latency test that came OK. I can summarize what I did if this can  helps others with simmilar issues.
The PC is an intel quad core q9550 2.83Ghz, asus maximus extreme (the first one) motherboard, 8Gb memory and a radeon 4550 graphics card, a pci wifi card and a mechanical HDD (I have a ssd ready once the install is OK and ready to clone)
First I went to the bios and disabled all non-necessary features; lan ports, ide controllers, audio, firewire, all I could think of. The results of latency test were around 80us, the histogram crazy, the plot made me suspect SMI issues and finally (or for starters) the error "Unexpected delay on task 0";
Edited the grub file, included the "quiet splash" and the "isolcpus=3", no luck. After reading some posts somebody said to open another terminal and use dmesg; oddly enough there was an error in ACPI: conflicting addresses.
I didn't touch acpi on the bios, turns out that acpi 2.0 was not enabled on bios, turned on this feature and the latency went to around 5us.
Turned off the screensaver, solved the nmtray icon appearing multiple times (It's in one post I can't remember) and took it from there.
Did the long script test and gave me 6.4us. I attach the hw and the lat file:
 

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Are this results consistent and real? Instead of vimeo I started a youtube video. I still have not figured how to turn off the PC speaker module; did some solutions offered in the forum but I don't know why it comes back.
Also I installed the last iso of linuxcnc (2.8) on an usb stick and had to do the trick of change the stick from one port to another and installed ok.
There are a lot of things to take into consideration... and I'm not even decided which pci-parallel port to buy, I intend to use mesa 7i76 and 5i25, but meantime a chepo bob and the pci-lpt1 will allow me to test the electronics.
Thanks for all the help provided in the forum.

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4 years 7 months ago #238147 by andypugh
Replied by andypugh on topic Results of latency test, list of computers tested for use with LinuxCNC

Are this results consistent and real?
 
Possibly. I have a machine that returns three-digit latency when idle, and about 2µs when working. 

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4 years 7 months ago #238193 by seuchato
Replied by seuchato on topic Results of latency test, list of computers tested for use with LinuxCNC

I still have not figured how to turn off the PC speaker module; did some solutions offered in the forum but I don't know why it comes back.
 
Hi
First off all: these are excellent results. Interesting enough, you got that with a ""RV710 [Radeon HD 4350/4550]". Is that an onboard GPU? Regarding pcspkr, see your .hw.txt. Excerpt as below:

================================================================================
Kernel modules data:
Check if pcspkr is loaded: Yes, may cause bigger latency.
can be eliminated using:
sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf

It really should not com back if you do the sudo line (in red). Never did for me.

hth
chris

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4 years 7 months ago #238198 by tallerseverino
Replied by tallerseverino on topic Results of latency test, list of computers tested for use with LinuxCNC

Hi
First off all: these are excellent results. Interesting enough, you got that with a ""RV710 [Radeon HD 4350/4550]". Is that an onboard GPU?
No, It's a pci-e gpu, I always did like the nvidia ones gt210 silent 1gb but it seems that nvidia causes problems, I found this one that resembles visually the nvidia made by asus, other than a bit of contact cleaner in the slot and such the card works fine in linux (mint, ubuntu) and in windows.

Regarding pcspkr, see your .hw.txt. Excerpt as below:
================================================================================
Kernel modules data:
Check if pcspkr is loaded: Yes, may cause bigger latency.
can be eliminated using:
sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf
It really should not com back if you do the sudo line (in red). Never did for me.

It comes back, I even did the commands using root and "rmmod pcspkr" I'll try again and report.
Thanks!

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4 years 7 months ago #238218 by seuchato
Replied by seuchato on topic Results of latency test, list of computers tested for use with LinuxCNC
pcspkr after "sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf"? That's strange! I'd check whether the sudo command was really successful:

cat /etc/modprobe.d/pcspkr.conf

Please check that and kindly report back
greez
chris

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4 years 7 months ago #238254 by tallerseverino
Replied by tallerseverino on topic Results of latency test, list of computers tested for use with LinuxCNC

pcspkr after "sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf"? That's strange! I'd check whether the sudo command was really successful:

cat /etc/modprobe.d/pcspkr.conf
Please check that and kindly report back
greez
chris

Finally It went away.
I did the commands, but sudo did not work, I had to use su and "rmmod" wasn't on the system path, had to use "\sbin\rmmod" to use the command. I have to check my knowledge of linux to set the corresponding path.
Ehm... It worked this time, It could be a typo when I tried, but the latency was the same after 2h of script test, even went up to 6.4uS (0.2uS up), but in the latency-plot I see spikes; I will have to check If they're periodical because It seems 64s, I suspect something to do with the intel chip on the MB. I will have to investigate.
Thanks!

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4 years 6 months ago #239818 by dmk1661
Replied by dmk1661 on topic Results of latency test, list of computers tested for use with LinuxCNC

seuchato said: Edit: 19. Oct. 2020: Actual price for CPU, Ram, Mobo and cooler is at 300€. I do have a case and powersupply already, stuff should be here coming weekend.

Hi - So how did the B460MD3H with Gold G6400 CPU work out? It is good for software stepping? What latency values are you seeing?
 I setup the Gigabyte B460M D3H, Pentium Gold 6400, SSD and on-board graphics with the latest preempt kernel for Debian 11. The worst case latency was around 30,000. This board will not work with Debian 10 with its on-board graphics. There is a documented bug with either the B460 Intel chipset or the Intel 610 on-chip GPU with the 4.19 something kernel. The bug results in no graphics. This is fixed with the Debian 11 kernel version 5 something. The user who reported results with the B460M D3H was using a PCIe AMD graphics card...I thought their latency was around 13k, but I'm not sure how to read that script output...it's not as clear as the basic latency test so 13k might not be correct. So it's possible better latency with an AMD PCIe graphics card.

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4 years 6 months ago #240319 by shellcrash
Replied by shellcrash on topic Results of latency test, list of computers tested for use with LinuxCNC
Finally figured out all the necessary kernel flags to get jitter below 20k. I thought the PC was trash initially because it was over 1M with BIOS settings disabled, but I fixed it after reading the forums and the documentation. Contrary to common practice, I currently have all the power/performance features enabled in BIOS with the kernel flags preventing power saving or bad behavior. The script was modified since old AMD AM2 motherboards report CPU temperature, not Core temperature, and I replaced the output from /etc/default/grub to the 2nd line from dmesg.
Code:
LinuxCNC pc tests, version 20200930, started 15.04.2022 08:49:29 ******************************************************************************** General info: ASUSTeK Computer INC.,  System Product Name Bios version 2801, dated 08/23/2010 Chipset: Harddisk is rotational The amount of swap currently used is 0 ================================================================================ CPU related data: model name    : Quad-Core AMD Opteron(tm) Processor 1354 cpu cores    : 4 stepping    : 3 cache size    : 512 KB ================================================================================ RAM related data: Maximum Capacity: 8 GB Size: 2048 MB Size: No Module Installed Size: 2048 MB Size: No Module Installed ================================================================================ GPU related data: product: RS780C [Radeon 3100] configuration: driver=radeon latency=0 ================================================================================ Parallel port related data: number of parallel ports is 1 parport0: PC-style at 0x378, irq 7 [PCSPP,TRISTATE] ================================================================================ Os and desktop related data: PRETTY_NAME="Debian GNU/Linux 10 (buster)" Should the info below not match with your machine, kindly post the output of pstree here, including a brief desciption of your desktop environment, window manager and display manager. Tia https://forum.linuxcnc.org/18-computer/39370-script-for-automated-testing-of-computer-latency Desktop environment : gnome Windowmanager       : Metacity (Marco) Displaymanager      : lightdm ================================================================================ Kernel related data: Kernel 4.19.195-rtai-amd64 [    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.19.195-rtai-amd64 root=UUID=4073631f-841a-4052-937d-db13e0ebdbd0 ro idle=poll isolcpus=3 irqaffinity=1,2 Cpu idle driver: ================================================================================ Kernel modules data: Check if pcspkr is loaded: Yes, may cause bigger latency.   can be eliminated using:   sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf Check if snd modules are loaded: Yes, may cause bigger latency.   can probably be disabled in bios, alternatively, you can run    "./block-snd-modules"    which has just now been created for your convenience. ================================================================================ Keyboard & Mouse related data: Number of mice: 1 Mouse 0 : USB Optical Mouse Mice  attached to USB: Avago Technologies, Pte. ADNS-5700 Optical Mouse Controller (3-button) Keyboards attached to USB: Lite-On Technology Corp. Keyboard ================================================================================ LinuxCNC related data: LinuxCNC version is: 2.8.2 ================================================================================ Preparing for latency test: Started glxgears No. 1, 2, 3, 4, 5 .......... Started firefox with 'https://vimeo.com/150574260', WID 58720259 ================================================================================ Command for latency test is: su fifi -c  "latency-histogram --bbinsize 1000 --base 25000 --sbinsize 1000 --nox 2>&1 | tee -a 1650026966.lat &" Latency testing loop started Fri 15 Apr 2022 08:49:44 AM EDT, should end after Fri 15 Apr 2022 10:49:44 AM EDT ================================================================================ Swap useage: prerun: 0, running: 0 ================================================================================ CPU temperatures: CPU 0: Tmin: 60.0°C, Tmax: 64.0°C, (high = +60.0°C, crit = +95.0°C) ================================================================================ last latency data is as follows:.  7205 secs   base min: -18.100 uS max:  18.700 uS sdev:   0.300 uS  7205 secs  servo min: -13.400 uS max:  13.600 uS sdev:   0.300 uS

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4 years 6 months ago #240334 by shellcrash
Replied by shellcrash on topic Results of latency test, list of computers tested for use with LinuxCNC
Tested an AM3 Phenom II x6 PC with an external graphics card. It also was configured with the RTAI kernel, however the system locks up if C1E is enabled in the BIOS when starting real time. The lockup did not occur with the preempt_rt kernel. I removed the entire temperature reporting portion of the latency test script for this because this lm_sensors does not report CPU temperature on this motherboard.
Code:
LinuxCNC pc tests, version 20200930, started 15.04.2022 11:49:43 ******************************************************************************** General info: BIOSTAR Group,  A870U3 Bios version 080015, dated 03/23/2012 Chipset: Harddisk is rotational The amount of swap currently used is 0 ================================================================================ CPU related data: model name    : AMD Phenom(tm) II X6 1035T Processor cpu cores    : 6 stepping    : 0 cache size    : 512 KB ================================================================================ RAM related data: Maximum Capacity: 8 GB Size: 4096 MB Size: 4096 MB Size: 4096 MB Size: 8192 MB ================================================================================ GPU related data: product: RV710 [Radeon HD 4350/4550] configuration: driver=radeon latency=0 ================================================================================ Parallel port related data: number of parallel ports is 1 parport0: PC-style at 0x378, irq 7 [PCSPP,TRISTATE] ================================================================================ Os and desktop related data: PRETTY_NAME="Debian GNU/Linux 10 (buster)" Should the info below not match with your machine, kindly post the output of pstree here, including a brief desciption of your desktop environment, window manager and display manager. Tia https://forum.linuxcnc.org/18-computer/39370-script-for-automated-testing-of-computer-latency Desktop environment : gnome Windowmanager       : Metacity (Marco) Displaymanager      : lightdm ================================================================================ Kernel related data: Kernel 4.19.195-rtai-amd64 Command line: BOOT_IMAGE=/boot/vmlinuz-4.19.195-rtai-amd64 root=UUID=325c60e8-39a5-47e1-b946-95e90ca3be25 ro idle=poll isolcpus=5 irqaffinity=1,2,3,4 Cpu idle driver: ================================================================================ Kernel modules data: Check if pcspkr is loaded: Yes, may cause bigger latency.   can be eliminated using:   sudo echo "install pcspkr /bin/true" >/etc/modprobe.d/pcspkr.conf Check if snd modules are loaded: Yes, may cause bigger latency.   can probably be disabled in bios, alternatively, you can run    "./block-snd-modules"    which has just now been created for your convenience. ================================================================================ Keyboard & Mouse related data: Number of mice: 1 Mouse 0 : USB Optical Mouse Mice  attached to USB: Avago Technologies, Pte. ADNS-5700 Optical Mouse Controller (3-button) Keyboards attached to USB: Lite-On Technology Corp. Keyboard ================================================================================ LinuxCNC related data: LinuxCNC version is: 2.8.2 ================================================================================ Preparing for latency test: Started glxgears No. 1, 2, 3, 4, 5 .......... Started firefox with 'https://vimeo.com/150574260', WID 60817411 ================================================================================ Command for latency test is: su layl -c  "latency-histogram --bbinsize 1000 --base 25000 --sbinsize 1000 --nox 2>&1 | tee -a 1650037776.lat &" Latency testing loop started Fri 15 Apr 2022 11:49:59 AM EDT, should end after Fri 15 Apr 2022 01:49:59 PM EDT ================================================================================ Swap useage: prerun: 0, running: 0 ================================================================================ last latency data is as follows:.  7201 secs   base min:  -5.400 uS max:   5.900 uS sdev:   0.200 uS  7201 secs  servo min:  -5.000 uS max:   5.000 uS sdev:   0.100 uS

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