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

Peter Zijlstra
2018-09-13T19:20:43Z

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(...);