Re: [PATCH v4 02/16] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups

[Peter Zijlstra]

On Wed, Sep 12, 2018 at 06:42:09PM +0100, Patrick Bellasi wrote:
> On 12-Sep 18:24, Peter Zijlstra wrote:
> > On Tue, Aug 28, 2018 at 02:53:10PM +0100, Patrick Bellasi wrote:

> > >  {
> > > + int group_id[UCLAMP_CNT] = { UCLAMP_NOT_VALID };
> > > + int lower_bound, upper_bound;
> > > + struct uclamp_se *uc_se;
> > > + int result = 0;
> > 
> > I think the thing would become much more readable if you set
> > lower/upper_bound right here.

> Actually it could also make sense to have them before the mutex ;)

Indeed.

+               upper_bound = (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX)
+                       ? attr->sched_util_max
+                       : p->uclamp[UCLAMP_MAX].value;
+               
+               if (upper_bound == UCLAMP_NOT_VALID)
+                       upper_bound = SCHED_CAPACITY_SCALE;
+               if (attr->sched_util_min > upper_bound) {
+                       result = -EINVAL;
+                       goto done;
+               }
+             
+               result = uclamp_group_find(UCLAMP_MIN, attr->sched_util_min);
+               if (result == -ENOSPC) {
+                       pr_err(UCLAMP_ENOSPC_FMT, "MIN");
+                       goto done;
+               }
+               group_id[UCLAMP_MIN] = result;
+       }
+       if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX) {
+               lower_bound = (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN)
+                       ? attr->sched_util_min
+                       : p->uclamp[UCLAMP_MIN].value;
+ 
+               if (lower_bound == UCLAMP_NOT_VALID)
+                       lower_bound = 0;
+               if (attr->sched_util_max < lower_bound ||
+                   attr->sched_util_max > SCHED_CAPACITY_SCALE) {
+                       result = -EINVAL;
+                       goto done;
+               }

That would end up soething like:

        unsigned int lower_bound = p->uclamp[UCLAMP_MIN].value;
        unsigned int upper_bound = p->uclamp[UCLAMP_MAX].value;

        if (sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN)
                lower_bound = attr->sched_util_min;

        if (sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX)
                upper_bound = attr->sched_util_max;

        if (lower_bound > upper_bound ||
            upper_bound > SCHED_CAPACITY_MAX)
                return -EINVAL;

        mutex_lock(...);