Which kernel version is best for real time?
- PCW
-
- Offline
- Moderator
-
Less
More
- Posts: 18577
- Thank you received: 5106
13 May 2025 14:24 - 13 May 2025 14:25 #328382
by PCW
Replied by PCW on topic Which kernel version is best for real time?
33 s32 RW 16640759 remora.read.tmax
I don't know the CPU clock frequency but if it's say 3 GHz, this is ~5 ms
so if you have a 1 ms servo thread, you are likely dropping packets
This indicates a network latency issue.
So possible the DKMS patch did not apply or there is still something
remaining wrong with the network setup.
I would run the ping test again, as it will show these issues clearly
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
I don't know the CPU clock frequency but if it's say 3 GHz, this is ~5 ms
so if you have a 1 ms servo thread, you are likely dropping packets
This indicates a network latency issue.
So possible the DKMS patch did not apply or there is still something
remaining wrong with the network setup.
I would run the ping test again, as it will show these issues clearly
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
Last edit: 13 May 2025 14:25 by PCW.
The following user(s) said Thank You: DarkPhoinix
Please Log in or Create an account to join the conversation.
- DarkPhoinix
- Offline
- Premium Member
-
Less
More
- Posts: 98
- Thank you received: 6
13 May 2025 15:11 #328388
by DarkPhoinix
Replied by DarkPhoinix on topic Which kernel version is best for real time?
33 s32 RW 16640759 remora.read.tmax
I don't know the CPU clock frequency but if it's say 3 GHz, this is ~5 ms
so if you have a 1 ms servo thread, you are likely dropping packets
This indicates a network latency issue.
So possible the DKMS patch did not apply or there is still something
remaining wrong with the network setup.
I would run the ping test again, as it will show these issues clearly
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.
--- 10.10.10.10 ping statistics ---
60000 packets transmitted, 60000 received, 0% packet loss, time 60017ms
rtt min/avg/max/mdev = 0.128/0.215/3.609/0.047 ms
####################################################
sudo lsmod | grep r8
r8168 581632 0
####################################################
sudo dmesg | grep r8
[ 0.024413] percpu: Embedded 62 pages/cpu s217088 r8192 d28672 u524288
[ 0.024419] pcpu-alloc: s217088 r8192 d28672 u524288 alloc=1*2097152
[ 0.936673] r8168: loading out-of-tree module taints kernel.
[ 0.936799] r8168: module verification failed: signature and/or required key missing - tainting kernel
[ 0.949871] r8168 Gigabit Ethernet driver 8.051.02-NAPI loaded
[ 0.982399] r8168: This product is covered by one or more of the following patents: US6,570,884, US6,115,776, and US6,327,625.
[ 0.982420] r8168 Copyright (C) 2022 Realtek NIC software team <nicfae@realtek.com>
[ 0.996908] r8168 0000:03:00.0 enp3s0: renamed from eth0
[ 8.722135] r8168: enp3s0: link up
Please Log in or Create an account to join the conversation.
- DarkPhoinix
- Offline
- Premium Member
-
Less
More
- Posts: 98
- Thank you received: 6
13 May 2025 15:21 - 13 May 2025 15:24 #328391
by DarkPhoinix
The module is this, they are update...
NO RUSTDESK
WITH RUSTDESK
Replied by DarkPhoinix on topic Which kernel version is best for real time?
sudo apt-get install r8168-dkms
Lettura elenco dei pacchetti... Fatto
Generazione albero delle dipendenze... Fatto
Lettura informazioni sullo stato... Fatto
r8168-dkms è già alla versione più recente (8.051.02-2).
0 aggiornati, 0 installati, 0 da rimuovere e 3 non aggiornati.The module is this, they are update...
NO RUSTDESK
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.
--- 10.10.10.10 ping statistics ---
60000 packets transmitted, 60000 received, 0% packet loss, time 59999ms
rtt min/avg/max/mdev = 0.154/0.210/0.417/0.027 msWITH RUSTDESK
sudo chrt 99 ping -i .001 -q -c 60000 10.10.10.10
PING 10.10.10.10 (10.10.10.10) 56(84) bytes of data.
--- 10.10.10.10 ping statistics ---
60000 packets transmitted, 60000 received, 0% packet loss, time 60006ms
rtt min/avg/max/mdev = 0.131/0.213/2.341/0.035 ms
Last edit: 13 May 2025 15:24 by DarkPhoinix.
Please Log in or Create an account to join the conversation.
- tommylight
-
- Away
- Moderator
-
Less
More
- Posts: 20229
- Thank you received: 6880
13 May 2025 15:35 #328396
by tommylight
Replied by tommylight on topic Which kernel version is best for real time?
You should really mention you keep using the remote desktop, not everyone here knows what RustDesk is.
And that begs the question, how is the NVEM wired to the PC?
So yes, rustdesk is causing issues, but if you are using a hub/switch, that is a big nono for machine control.
And that begs the question, how is the NVEM wired to the PC?
So yes, rustdesk is causing issues, but if you are using a hub/switch, that is a big nono for machine control.
The following user(s) said Thank You: DarkPhoinix
Please Log in or Create an account to join the conversation.
- DarkPhoinix
- Offline
- Premium Member
-
Less
More
- Posts: 98
- Thank you received: 6
13 May 2025 16:44 #328400
by DarkPhoinix
Replied by DarkPhoinix on topic Which kernel version is best for real time?
So why do they do these tests with 4 YouTube videos in 4k in the forum? in direct connection with stress test 100 GLXgears I can work safely even with NVIDIA! I got this AMD VGA and now I also bought a motherboard with HDMI output to pass the YouTube 4K video test!You should really mention you keep using the remote desktop, not everyone here knows what RustDesk is.
And that begs the question, how is the NVEM wired to the PC?
So yes, rustdesk is causing issues, but if you are using a hub/switch, that is a big nono for machine control.
Please Log in or Create an account to join the conversation.
- langdons
- Offline
- Platinum Member
-
Less
More
- Posts: 342
- Thank you received: 34
13 May 2025 18:02 #328405
by langdons
Replied by langdons on topic Which kernel version is best for real time?
Don't use remote desktop while running the latency test.
And why use rustdesk?
VNC or RDP are preinstalled and good.
Don't install stuff unless you really need it.
And why use rustdesk?
VNC or RDP are preinstalled and good.
Don't install stuff unless you really need it.
Please Log in or Create an account to join the conversation.
- tommylight
-
- Away
- Moderator
-
Less
More
- Posts: 20229
- Thank you received: 6880
13 May 2025 19:03 #328408
by tommylight
Same thing with GlxGears, video, but easier to run, but this also uses OpenGL that is used by LinuxCNC, namely Gremlin uses it to display the stuff being cut. We use 10 as it is very lite on resources, but 100?
You keep mentioning that under stress it works fine (even unresponsive, and this is something Linux does magnificently), so you can try adding a base period and test some values till you get something that gets rid of errors/issues.
Probably something like this should do, add to hal file:You can safely try from 10000 to 500000 (10K to 500K), above would probably not help at all and below might cause the PC to slow down.
Replied by tommylight on topic Which kernel version is best for real time?
Youtube is used to stress the video subsystem as video uses interrupts that require the PC to halt until whatever is requested by that interrupt is finished, then go on to do other stuff, and so on. I am not aware of anywhere being stated you must use 4 youtube videos, if you are, please let us know so we can fix that. A single window maximizing and minimizing is enough to trigger latency excursions, so 4 are overkill and prove nothing.So why do they do these tests with 4 YouTube videos in 4k in the forum? in direct connection with stress test 100 GLXgears I can work safely even with NVIDIA! I got this AMD VGA and now I also bought a motherboard with HDMI output to pass the YouTube 4K video test!
Same thing with GlxGears, video, but easier to run, but this also uses OpenGL that is used by LinuxCNC, namely Gremlin uses it to display the stuff being cut. We use 10 as it is very lite on resources, but 100?
You keep mentioning that under stress it works fine (even unresponsive, and this is something Linux does magnificently), so you can try adding a base period and test some values till you get something that gets rid of errors/issues.
Probably something like this should do, add to hal file:
loadrt base_period_nsec=100000Please Log in or Create an account to join the conversation.
- DarkPhoinix
- Offline
- Premium Member
-
Less
More
- Posts: 98
- Thank you received: 6
13 May 2025 19:26 #328411
by DarkPhoinix
Replied by DarkPhoinix on topic Which kernel version is best for real time?
forum.linuxcnc.org/38-general-linuxcnc-q...ults?start=40#327937
100 glxgears windows += no junction error
4k youtube video (1 or 2 or 3 or 4 windows) with or not remote connection = junction error
in need put like this in hal file:
i think the problem is not video but the network load.... i can't try a youtube video offline... i do not why people tell to use this test for combo network + vga load??
I am newbee i read and make ... i try the way of new version kernel fot test but the new kernel give me more latency.
I ma near to finish the CNC, next try real work for test ...
Sorry all for my bad bad english.
100 glxgears windows +
stress --cpu 4 --io 4 --vm 4 --vm-bytes 1500M --timeout 200s4k youtube video (1 or 2 or 3 or 4 windows) with or not remote connection = junction error
in need put like this in hal file:
#load the Remora real-time component
loadrt remora-eth-3.0 PRU_base_freq=500000
loadrt base_period_nsec=100000i think the problem is not video but the network load.... i can't try a youtube video offline... i do not why people tell to use this test for combo network + vga load??
I am newbee i read and make ... i try the way of new version kernel fot test but the new kernel give me more latency.
I ma near to finish the CNC, next try real work for test ...
Sorry all for my bad bad english.
Please Log in or Create an account to join the conversation.
- langdons
- Offline
- Platinum Member
-
Less
More
- Posts: 342
- Thank you received: 34
13 May 2025 20:07 #328415
by langdons
Replied by langdons on topic Which kernel version is best for real time?
I you want to play a video sans internet, play this .mp4 on the default video player (If debian even has one) or VLC (or some other file, VLC can literally play any and every video format):
www2.langdonstaab.ca/files/hai-yorokonde.mp4
www2.langdonstaab.ca/files/hai-yorokonde.mp4
Please Log in or Create an account to join the conversation.
- tommylight
-
- Away
- Moderator
-
Less
More
- Posts: 20229
- Thank you received: 6880
13 May 2025 21:24 #328421
by tommylight
Replied by tommylight on topic Which kernel version is best for real time?
Yes that is the correct place to put it.
While testing this, no stress test, no glxgears, no video, no youtube.
While testing this, no stress test, no glxgears, no video, no youtube.
Please Log in or Create an account to join the conversation.
Time to create page: 0.124 seconds