Re: [Xenomai-help] Standard linux assignment of processes to CPUs depends on Xenomai Config

["Dmitry Adamushko" <dmitry.adamushko@domain.hid>]

On 19/02/07, Philippe Gerum <rpm@xenomai.org> wrote:
> On Mon, 2007-02-19 at 13:13 +0100, Dmitry Adamushko wrote:
> > > > ...
> > > > #ifdef CONFIG_SMP
> > > >         /* Make sure the init sequence is kept on the same CPU when
> > > >            running as a module. */
> > > >         set_cpus_allowed(current, cpumask_of_cpu(0));
> > > > #endif /* CONFIG_SMP */
> > > >
> > > > In fact, "running as a module" seems to be a bit
> > > > misleading here.  Then another macro should be used in addition,
> > > > MODULE or how it's called.
> > > >
> > > > Now guess who is a "current" here? It's "init" (pid 0).
> > > >
> > > > init() -> do_basic_setup() -> do_initcalls() -> ... ->
> > > > __xeno_sys_init() -> xnarch_init()
> > > >
> > > > "init" is a first process to run and all the rest will inherit its
> > > > "cpus_allowed" field.
> > > >
> > > > That's it.
> > > >
> > >
> > > Eh, that's what I call a nice one Dmitry. This is the perfect example of
> > > legacy code stabbing us in the back. We should indeed definitely check
> > > for MODULE && SMP.
> >
> > Yep, as the very least. But even in this case, it's not very nice that
> > via cpus_allowed we affect - scheduling-wise - a process which loads
> > xeno modules and all its children as It's likely to be a shell.
>
> It's insmod.

Oh yep :) Don't think it's a problem then. SMP && MODULE should be ok.

> --
> Philippe.
>

-- 
Best regards,
Dmitry Adamushko