[yocto] Can I disable RT throttling?

[David Mulder]

> > Will that work on a core that's offline?
> 
> Nope. Only with an online core controlled by the Linux scheduler.
> If you do end up trying to get AMP working, you need to plumbing
> to load the other OS/kernel in a reserved memory location, set the
> program counter and start the OS.
> 
> But that secondary OS has to know how to behave in a system that
> it doesn't control, and you'll need ways to communicate with it
> from Linux.
> 
> remoteproc/rpmsg can solve some of the issues that I mention, but
> it is far from out of the box.
> 
> That's why there's more interest in running a single task with
> exclusive CPU in userspace. The work and scaffolding required to
> get an AMP system up and running is non trivial.

I kinda thought so, but I was hopeful.

After speaking with some co-workers, I have a new perspective on these delays:  yes, we are trying to do a 10us control loop, but if we miss a step or two occasionally we can accept that.  And looking online I see people indicating context switch times well below 10us (Core-i cpus), which is better than I had anticipated, and should be workable.  So I'm going to approach this problem by just trying to squeeze the kernel as much as I can.  Some things that I see to squeeze are /dev/cpu_dma_latency (should be 0) or max_cstate (should be as low as possible (0, maybe 1)), possibly idle=poll.  Are there other kernel parameters that can minimize kernel interference/time?  And perhaps hints about how to set them in Yocto or menuconfig?

Thanks!
Dave