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Subject: Re: [RFC][PATCH 02/22] sched: add extended scheduling interface
From: Raistlin <raistlin@linux.it>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
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        Nicola Manica <nicola.manica@disi.unitn.it>,
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On Thu, 2010-11-11 at 14:32 +0100, Peter Zijlstra wrote:
> > BTW, as Dhaval was suggesting, are (after those changes) fine with this
> > new sched_param? Do we need some further mechanism to grant its
> > extendability?
> > Padding?
> > Versioning?
> > void *data field?
> > Whatever?
> >=20
> > :-O
> >=20
> > I'd like very much to have some discussion here, if you think it is
> > needed, in hope of avoiding future ABI issues as much as possible! :-P
>=20
> Right, so you mentioned doing s/_ex/2/ on all this stuff, which brings
> it more in line with that other syscalls have done.
>=20
Sure, this is necessary and easy to achieve. :-)

> The last three parameters look to be output only as I've not yet found
> code that reads it, and __getparam_dl() doesn't even appear to set
> used_runtime.
>=20
Yeah, just kind of statistical reporting of the task's behaviour. That's
why I was in agreement with Dhaval about using schedstats for those
(bumping the version, obviously). What do you think?

> One thing you can do is add some padding, versioning and void*
> extentions are doable for the setparam() path, but getparam() is going
> to be mighty interesting.
>=20
Mmm... So, tell me if I got it well: I remove the last three parameters
(e.g., moving them toward schedstats) and add (besides _var and _max)
some padding? It that correct?

what about the len <=3D=3D sizeof(struct sched_param2) in
sched_{set,get}{param,scheduler}2()... Does this still make sense, or
are we removing it?

Thanks,
Dario

--=20
<<This happens because I choose it to happen!>> (Raistlin Majere)
----------------------------------------------------------------------
Dario Faggioli, ReTiS Lab, Scuola Superiore Sant'Anna, Pisa  (Italy)

http://blog.linux.it/raistlin / raistlin@ekiga.net /
dario.faggioli@jabber.org

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