Latency
24 Jan 2024 23:13 #291557
by garja
PCW... I was told you know a lot about latency issues.
I'm using a Mesa 7i96S card.
My computer is a Fujitsu i5-6500 3.2 GHZ with 8 MB ram.
I've installed LinuxCNC 2.9.2 Debian Bookworm.
According to the latency test window, kernel version
=#1 SMP-Preempt_RT Debian 6.1.67-1 (2023-12-12)
When I run a latency test I get numbers like 367.
I've tried disabling the onboard graphics and used a PCIe 3.0 AMD video card. Still get the same results. In the CMOS there was a cpu setting that allowed me to use just one thread. Using just one thread yields the same results.
If I run latency-histogram --no base --sbinsize 1000 and 3 glxgear windows, my max (us) is 115.4 after just 300 seconds. It jumps to 167.2 after just 650 second.
Any thoughts that might be helpful to me?
Thanks... Garlen
I'm using a Mesa 7i96S card.
My computer is a Fujitsu i5-6500 3.2 GHZ with 8 MB ram.
I've installed LinuxCNC 2.9.2 Debian Bookworm.
According to the latency test window, kernel version
=#1 SMP-Preempt_RT Debian 6.1.67-1 (2023-12-12)
When I run a latency test I get numbers like 367.
I've tried disabling the onboard graphics and used a PCIe 3.0 AMD video card. Still get the same results. In the CMOS there was a cpu setting that allowed me to use just one thread. Using just one thread yields the same results.
If I run latency-histogram --no base --sbinsize 1000 and 3 glxgear windows, my max (us) is 115.4 after just 300 seconds. It jumps to 167.2 after just 650 second.
Any thoughts that might be helpful to me?
Thanks... Garlen
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24 Jan 2024 23:36 #291561
by garja
Hey... thank you so much for your quick response.
I didn't get any errors just high numbers. I was able to connect to the Mesa 7i96s card and when I ping it I don't get any errors either. John from Mesa mentioned that you had commented
"Also as long as you do not suffer real time errors or Ethernet timeouts the latency is largely irrelevant."
I was able to ping my Mesa card and did not see any timeouts. Maybe there is another way to test to see if I do get any Ethernet timeouts?
I didn't get any errors just high numbers. I was able to connect to the Mesa 7i96s card and when I ping it I don't get any errors either. John from Mesa mentioned that you had commented
"Also as long as you do not suffer real time errors or Ethernet timeouts the latency is largely irrelevant."
I was able to ping my Mesa card and did not see any timeouts. Maybe there is another way to test to see if I do get any Ethernet timeouts?
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25 Jan 2024 02:06 #291566
by garja
I've only connected the Mesa card and connected through my Ethernet card and pinged it to make sure I had it setup correctly. I've not started the actual setup of Debian Bookworm 2.9.2. I guess my next step is to complete the Pncconf wizard or should I run a Mesa wizard before I do the Pncconf wizard. I guess I'm not sure what to do next.
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29 Jan 2024 11:38 #291884
by vmihalca
I do get latency errors from linuxcnc. I am using Mesa 7i97.
Debian bookworm, linuxcnc 2.9.2 compiled from sources.
I got max jitter on servo thread 1553904.
On the same PC while I was using debian 10 I had no complains about the latency.
Nothing in the bios was changed since then.
The machine seems to run fine, but I've mostly run test programs as I am still working on it.
Debian bookworm, linuxcnc 2.9.2 compiled from sources.
I got max jitter on servo thread 1553904.
On the same PC while I was using debian 10 I had no complains about the latency.
Nothing in the bios was changed since then.
The machine seems to run fine, but I've mostly run test programs as I am still working on it.
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10 Feb 2024 23:31 #293044
by tommylight
Replied by tommylight on topic Latency
Not me, but if you do run on latency issues, try this first:
forum.linuxcnc.org/38-general-linuxcnc-q...ead-and-irq-affinity
forum.linuxcnc.org/38-general-linuxcnc-q...ead-and-irq-affinity
The following user(s) said Thank You: garja
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11 Feb 2024 14:28 #293092
by garja
The following user(s) said Thank You: tommylight
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