Re: [Xenomai-help] [Newbie question] threads and task CPU affinity

[Jan Kiszka <jan.kiszka@domain.hid>]

[-- Attachment #1: Type: text/plain, Size: 1308 bytes --]

RAKOTOSALAMA, Nirilanto wrote:
> Hello,
> 
> I have some question about CPU affinity with Xenomai 2.3.1.
> (it is to see if  xenomai support developing for a cpu manager library is feasible)

What will this library do? (/me just nosy)

> 
> When using rt_task_create, CPU mask can be specified. However, when sched_setaffinity is called 
> to modify main program affinity, and after, rt_task_create is called without specifying CPU mask,
> did the child task inherits from the main program affinity ?

If you don't provide a target CPU (either on creation or via
/proc/xenomai/affinity), better consider the affinity as unspecified
(any possible CPU). The target CPU derives from Linux decision where to
put the thread non-RT boot code on, Xenomai just nails that decision
down until someone explicitly migrates.

> 
> Same question for Posix skin threads ?
> 
> Can native task affinity be set other than when creating ? using sdhed_setaffinity ?

/proc/xenomai/affinity (has global scope) or sched_setaffinity. Xenomai
shadow threads follow the migration that may took place while in
secondary mode, and sched_setaffinity comes with such a mode switch.

> 
> Can posix skin thread affinity be set using sched_affinity ?
> 
> 
> Thanks in advance.
> 
> Niry.
> 

Jan


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 250 bytes --]