otrd., 2026. g. 20. janv., plkst. 12:08 — lietotājs andy pugh
(<[email protected]>) rakstīja:
>
> If you can't find it under Ubuntu then you could try downloading the
> deb from debian:
> https://packages.debian.org/trixie/amd64/linux-image-6.12.63+deb13-rt-amd64/download
>

Thank you! It needed downloading also linux-base as dependency package
and now I have it. It is just that latency histogram looks even worse.
Max period is almost 68 ms!!!
https://ibb.co/ymgV0ktq

BTW it was posix realtime also with that 5.15.intel_iot kernel

otrd., 2026. g. 20. janv., plkst. 09:32 — lietotājs Robert Schöftner
(<[email protected]>) rakstīja:
>
> Some stuff you could explore: cpuidle and cpufreq. for the "isolcpus"
> cores, you want some medium fixed speed (even 1ghz should be
> sufficient) and disabled deep sleep and no frequency scaling.
>

Thank you Robert for suggestions!
Here are specs of that cpu, there really are 12 cores:
https://www.intel.com/content/www/us/en/products/sku/237328/intel-core-ultra-5-processor-135u-12m-cache-up-to-4-40-ghz/specifications.html
I did isolate cpu cores 8 and 9, last 2 of the efficient cores.

In BIOS I have made following changes:
Block Sleep is OFF
Intel AMT capability = disabled
Intel Virtualization technology = OFF
Intel SpeedStep = OFF
C-States control = OFF
Intel TurboBoost technology = OFF
Intel Hyperthreading = OFF

I found this page: https://docs.kernel.org/admin-guide/kernel-parameters.html

This is histogram with GRUB_CMD_LINUX_DEFAULT="quiet isolcpus 8,9
cpufreq.default_governor=performance cpuidle.off=1":
https://ibb.co/ymgV0ktq

Then I decided to isolate one of the performance cores, the difference is huge!
This is histogram with GRUB_CMD_LINUX_DEFAULT="quiet isolcpus 1
cpufreq.default_governor=performance cpuidle.off=1":
https://ibb.co/6cRzWXyL

I was not sure if it makes any sense to add "intel_idle.max_cstate=0"
and "processor.max_cstate=0" but decided that there is only one way to
find out for sure.
This is with GRUB_CMD_LINUX_DEFAULT="quiet isolcpus 1
cpufreq.default_governor=performance cpuidle.off=1
intel_idle.max_cstate=0 processor.max_cstate=0":
https://ibb.co/WWQ6C5Lj


>
> use the "cpupower" command to monitor frequency
>

My apologies but I am not sure I understand this. Is that a command to
run in terminal?

>
> set cpu frequency governor to "performance":
>
> echo -n performance | sudo tee
> /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
>

Ok, did set the governor, but I am not sure about the latter - is that
one command or 2 separate commands?

>
> I guess positioning of the induction coil doesn't need to be very
> precise or fast and timing is also not that critical, so you could
> probably get away with a way slower servo thread (500kHz / 250kHz).
>

I actually did that on old laptop, increased servoperiod to 2ms but
colleagues who supervise the experiments have told me about Mesa card
read errors.

>
> on the old laptop that sometimes has comm problem with mesa card, check
> if it is intel network chip (lspci) and if so check/add irq coalescing
> setting (man hm2_eth)
>

Result of lspci command indicates that there is Intel network
controller so I will implement that as well.

>
> you could also try to pin the IRQ of the network interface to a core so
> it doesn't move around, maybe even to one of the "isolcpu" cores
>

How do I do that? I have a feeling that I can isolate one or two more cores.

Viesturs


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