Re: [RFC][PATCH 02/22] sched: add extended scheduling interface

[Dhaval Giani]

On Thu, Nov 11, 2010 at 02:32:13PM +0100, Peter Zijlstra wrote:
> On Wed, 2010-11-10 at 23:17 +0100, Raistlin wrote:
> > On Wed, 2010-11-10 at 18:28 +0100, Peter Zijlstra wrote:
> > > On Fri, 2010-10-29 at 08:27 +0200, Raistlin wrote:
> > > > +struct sched_param_ex {
> > > > +       int sched_priority;
> > > > +       struct timespec sched_runtime;
> > > > +       struct timespec sched_deadline;
> > > > +       struct timespec sched_period;
> > > > +       unsigned int sched_flags;
> > > > +
> > > > +       struct timespec curr_runtime;
> > > > +       struct timespec used_runtime;
> > > > +       struct timespec curr_deadline;
> > > > +}; 
> > > 
> > > It would be better for alignment reasons to move the sched_flags field
> > > next to the sched_priority field.
> > > 
> > Makes sense, thanks. :-)
> > 
> > > I would suggest we add at least one more field so we can implement the
> > > stochastic model from UNC, sched_runtime_dev or sched_runtime_var or
> > > somesuch.
> > > 
> > Ok, no problem with that too.
> > 
> > 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?
> > 
> > :-O
> > 
> > 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
> 
> Right, so you mentioned doing s/_ex/2/ on all this stuff, which brings
> it more in line with that other syscalls have done.
> 
> 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.
> 

So, do you think its a good idea moving this information to schedstats?
It seems more in line for monitoring, which schedstat seems a more
appropriate destination.

thanks,
Dhaval
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