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

Patrick Bellasi
2018-09-06T14:00:34Z

On 06-Sep 10:17, Juri Lelli wrote:
> On 28/08/18 14:53, Patrick Bellasi wrote:
>
> [...]
>
> > static inline int __setscheduler_uclamp(struct task_struct *p,
> > const struct sched_attr *attr)
> > {
> > - if (attr->sched_util_min > attr->sched_util_max)
> > - return -EINVAL;
> > - if (attr->sched_util_max > SCHED_CAPACITY_SCALE)
> > - return -EINVAL;
> > + int group_id[UCLAMP_CNT] = { UCLAMP_NOT_VALID };
> > + int lower_bound, upper_bound;
> > + struct uclamp_se *uc_se;
> > + int result = 0;
> >
> > - p->uclamp[UCLAMP_MIN] = attr->sched_util_min;
> > - p->uclamp[UCLAMP_MAX] = attr->sched_util_max;
> > + mutex_lock(&uclamp_mutex);
> >
> > - return 0;
> > + /* Find a valid group_id for each required clamp value */
> > + if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MIN) {
> > + 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;
> > + }
> > +
> > + result = uclamp_group_find(UCLAMP_MAX, attr->sched_util_max);
> > + if (result == -ENOSPC) {
> > + pr_err(UCLAMP_ENOSPC_FMT, "MAX");
> > + goto done;
> > + }
> > + group_id[UCLAMP_MAX] = result;
> > + }
>
> Don't you have to reset result to 0 here (it seems what follows cannot
> fail anymore)? Otherwise this function will return latest
> uclamp_group_find return value, which will be interpreted as error if
> not 0.

Yes, wired.. it uses to work on my tests just because I return from
the caller on !0 and:
- that's just good enough to set by uclamps
- my current rt-app integration does not check the sycall return value
- my tests never request the clamp_group mapped on group_id=0

:(

Will fix both this and the rt-app integration and the tests !

Cheers Patrick

--
#include <best/regards.h>

Patrick Bellasi