From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Tue, 22 May 2007 18:59:50 +0200
From: Jan Kiszka <jan.kiszka@domain.hid>
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Subject: Re: [Xenomai-help] [Newbie question] threads and task CPU affinity
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To: "RAKOTOSALAMA, Nirilanto" <NIRILANTO.RAKOTOSALAMA@airbus.com>
Cc: xenomai@xenomai.org

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RAKOTOSALAMA, Nirilanto wrote:
> Hello,
>=20
> 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)

>=20
> When using rt_task_create, CPU mask can be specified. However, when sch=
ed_setaffinity is called=20
> to modify main program affinity, and after, rt_task_create is called wi=
thout 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.

>=20
> Same question for Posix skin threads ?
>=20
> 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.

>=20
> Can posix skin thread affinity be set using sched_affinity ?
>=20
>=20
> Thanks in advance.
>=20
> Niry.
>=20

Jan


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