Re: [Xenomai] Suggested approach to schedule N-RT work in kernel on a specific CPU core

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

On Sun, Mar 20, 2016 at 07:49:16AM +0000, Alex Plits wrote:
> 
> 
> > -----Original Message-----
> > From: Gilles Chanteperdrix [mailto:gilles.chanteperdrix@xenomai.org]
> > If the Linux kernel provides a function to do this, we could implement a
> > function mirroring that function in the RTDM API. Looks simple. Am I missing
> > something ?
> > 
> 
> [Alex Plits] The Linux provides an option to configure the workQ
> on specific CPU's on it's initialization stage of the WorkQ. I'm
> unsure Of how/whether it actually schedules it's execution when
> schedule_work is called from a different CPU core that it was
> configured up-on.

I doubt very much this does not work. Have you tried it and observed
that it does not work?



> I'm guessing that if it were trivial the same
> mechanism would also be used in the current API for N-RT or
> xenomai printk mechanism (both use dedicated workQs which are
> different than Linux WorkQs awaken via VIRQs).

There is no xenomai printk mechanism. printk is implemented by the
I-pipe patch, a layer below Xenomai, so can not use an RTDM service.
Besides, the I-pipe patch printk implementation predates
ipipe_post_work_root.

The way RTDM work works is with the ipipe_post_work_root service,
so it does not use virqs, and since the schedule_work gets invoked
in a plain linux context, anything which works with schedule_work
(like triggering a work queue on a different cpu) should work with
the RTDM service.

So, again, have you tried running the RTDM service with a work queue
pinned on a different cpu and observed that it did not work?

-- 
					    Gilles.
https://click-hack.org