Re: [PATCH v5 03/15] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups

[Peter Zijlstra]

On Wed, Nov 07, 2018 at 02:19:49PM +0000, Patrick Bellasi wrote:
> On 07-Nov 13:19, Peter Zijlstra wrote:
> > On Mon, Oct 29, 2018 at 06:32:57PM +0000, Patrick Bellasi wrote:
> > > +struct uclamp_se {
> > > +	unsigned int value		: SCHED_CAPACITY_SHIFT + 1;
> > > +	unsigned int group_id		: order_base_2(UCLAMP_GROUPS);
> > 
> > Are you sure about ob2() ? seems weird we'll end up with 0 for
> > UCLAMP_GROUPS==1.
> 
> So, we have:
> 
>    #define UCLAMP_GROUPS (CONFIG_UCLAMP_GROUPS_COUNT + 1)
> 
> because one clamp group is always reserved for defaults.
> Thus, ob2(in) is always called with n>=2.
> 
> ... should be safe no ?

+config UCLAMP_GROUPS_COUNT
+       int "Number of different utilization clamp values supported"
+       range 0 32
+       default 5

0+1 == 1

Increase the min range and you should be good I think.