Re: [RFC][PATCH 8/9] sched: power: Add initial frequency scaling support to power scheduler

[Catalin Marinas <catalin.marinas@arm.com>]

On Fri, Jul 12, 2013 at 01:51:13PM +0100, Morten Rasmussen wrote:
> On Wed, Jul 10, 2013 at 02:10:59PM +0100, Arjan van de Ven wrote:
> > On 7/9/2013 8:55 AM, Morten Rasmussen wrote:
> > > Extends the power scheduler capacity management algorithm to handle
> > > frequency scaling and provide basic frequency/P-state selection hints
> > > to the power driver.
> > >
> > > Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
> > > CC: Ingo Molnar <mingo@kernel.org>
> > > CC: Peter Zijlstra <peterz@infradead.org>
> > > CC: Catalin Marinas <catalin.marinas@arm.com>
> > > ---
> > >   kernel/sched/power.c |   33 ++++++++++++++++++++++++++++-----
> > >   1 file changed, 28 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/kernel/sched/power.c b/kernel/sched/power.c
> > > index 9e44c0e..5fc32b0 100644
> > > --- a/kernel/sched/power.c
> > > +++ b/kernel/sched/power.c
> > > @@ -21,6 +21,8 @@
> > >
> > >   #define INTERVAL 5 /* ms */
> > >   #define CPU_FULL 90 /* Busy %-age - TODO: Make tunable */
> > > +#define CPU_TARGET 80 /* Target busy %-age - TODO: Make tunable */
> > > +#define CPU_EMPTY 5 /* Idle noise %-age - TODO: Make tunable */
> > >
> > 
> > to be honest, this is the policy part that really should be in the hardware specific driver
> > and not in the scheduler.
> > (even if said driver is sort of a "generic library" kind of thing)
> 
> I agree that the values should be set by a hardware specific power
> driver. Or do you mean that algorithms using this sort of values should
> be in the driver?

I think for flexibility we could place the default algorithm in a
library and it would be used by the cpufreq power driver wrapper or
directly by a new power driver. The intel_pstate.c driver could be
allowed to do smarter things.

-- 
Catalin