Re: How to add scheduler

[Peter Williams]

On 27/10/09 17:30, Pankaj Parakh wrote:
> On Sat, Oct 24, 2009 at 6:07 AM, Peter Williams<pwil3058@xxxxxxxxxxxxxx>  wrote:
> > On 24/10/09 01:10, Pankaj Parakh wrote:
> > > Hi Peter,
> > >
> > > Thanks for showing your interest, I am student and I am working on a
> > > project similar to yours i.e. to have a facility where in one can swap
> > > scheduler in run-time, but I am in very initial state of learning so I
> > > wanted to try a simple RR scheduler, objective of doing it is to learn
> > > about different interfaces in modular design(introduced from 2.6.23
> > > with CFS). I do not have any constraint with version of linux. I am
> > > ready to take part with you provided you do not have any issue.
> >
> > No.  That's good.
> >
> > I've attached two patches which contain the work I've done so far.  They
> > should be applied in the following order:
> >
> > define_prelim_cpu_pisch_drv.patch
> > implement_spbrr_cpu_pisch_dvr.patch
> >
> > and will result in two schedulers: the default CFS 'fair' (cfs_fair)
> > scheduler and a simple priority based round robin (spbrr) scheduler; being
> > available for selection at boot time and run time.
> >
> > To select a scheduler at boot time just add 'cpu_pisch=cfs_fair' or
> > 'cpu_pisch=spbrr' to the boot command line.
> >
> > To select a scheduler at run time (as root) do:
> >
> > echo -n 'cfs_fair'>  /sys/kernel/cpu_pisch/name
> >
> > or
> >
> > echo -n 'spbrr'>  /sys/kernel/cpu_pisch/name
> >
> > The first step in adding your own scheduler would be to make a copy of the
> > file kernel/cpu_pisch_spbrr.c and then modify it.  You will also need to
> > modify:
> >
> > kernel/sched.c
> > kernel/cpu_pisch_drv.c
> > kernel/Kconfig.cpu_pisch
> >
> > Hopefully, the required changes are obvious.  If not don't hesitate to ask
> > questions.  Also if you feel the need to modify the scheduler interface
> > (defined in include/linux/cpu_pisch_drv.h) feel free BUT think very
> > carefully about it and try not to make things too complex.
> >
> > I am working on another scheduler (a simple entitlement based round robin
> > (sebrr) scheduler) which I hope to have finished before I publicly release
> > the patches.
> >
> > If you wish to have your scheduler included just send it to me as a patch
> > which applies on top of the ones that I've attached.
> >
> > Cheers
> > Peter
> > --
> > Peter Williams                                   pwil3058@xxxxxxxxxxxxxx
> >
> > "Learning, n. The kind of ignorance distinguishing the studious."
> >   -- Ambrose Bierce
>
> Hi Peter,
>
> To which version of Linux Kernel should I apply the given patch.

Those patches were against 2.6.32-rc5 but they may also apply cleanly to 
later versions.

--
Peter Williams                                   pwil3058@xxxxxxxxxxxxxx

"Learning, n. The kind of ignorance distinguishing the studious."
 -- Ambrose Bierce
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