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edison-fw / meta-intel-edison

Here is the meta-intel-edison that builds, tries to stay up to date. Master is based on Yocto Poky Gatesgarth LTS 5.10.yy vanilla kernels. It builds a 32bit kernel (Gatesgarth branch 64bit) with ACPI enabled and corresponding rootfs. Telegram group: https://t.me/IntelEdison Web-site:
https://edison-fw.github.io/meta-intel-edison/
MIT License
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Preempt-RT support #127

Closed mwallnoefer closed 3 years ago

mwallnoefer commented 3 years ago

Interesting to see how the _PREEMPTRT effort continues its way to be integrated into the mainline kernel: https://wiki.linuxfoundation.org/realtime/start

Could it make sense to build the Edison images with a _preemptrt-based kernel per default? Also to provide an alternative to the internal MCU which currently isn't really usable afaik?

htot commented 3 years ago

I like it, but in case of troubles might be difficult to get support from kernel developers? If found the bugs hurting us (eem ethernet over gadget) are the same for -rt and normal kernel. So the only real downside it reduced performance that you can notice as a reduced ethernet speed (iperf3).

BTW we have a Telegram group called Intel Edison https://t.me/IntelEdison

mwallnoefer commented 3 years ago

If found the bugs hurting us (eem ethernet over gadget) are the same for -rt and normal kernel. So the only real downside it reduced performance that you can notice as a reduced ethernet speed (iperf3).

Okay, maybe things get better in the future, when the whole rt patchset lands in the vanilla kernel.

htot commented 3 years ago

I would say reduced performance in some area's is to be expected, in particular like eem ethernet (gadget) as it involves dwc3 interrupts. The -rt patch converts interrupts to tasklets so they can be made interruptible by higher priority tasklets. This is the essence of the -rt patch, to reduced latencies at the expense of throughput.

With the -rt patch is see latencies 50 - 100 us, without -rt patch sometimes spikes to 100ms.

htot commented 3 years ago

With dunfell there is a -rt kernel provided.