[PATCH v8 10/16] sched/core: uclamp: Add uclamp_util_with()

[Patrick Bellasi]

So far uclamp_util() allows to clamp a specified utilization considering
the clamp values requested by RUNNABLE tasks in a CPU. For the Energy
Aware Scheduler (EAS) it is interesting to test how clamp values will
change when a task is becoming RUNNABLE on a given CPU.
For example, EAS is interested in comparing the energy impact of
different scheduling decisions and the clamp values can play a role on
that.

Add uclamp_util_with() which allows to clamp a given utilization by
considering the possible impact on CPU clamp values of a specified task.

Signed-off-by: Patrick Bellasi <patrick.bell...@arm.com>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Peter Zijlstra <pet...@infradead.org>

---
Changes in v8:
 Others:
 - s/uclamp_effective_value()/uclamp_eff_value()/
---
 kernel/sched/sched.h | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index b4c13f3beb2f..a1ed3d94652a 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2276,11 +2276,20 @@ static inline void cpufreq_update_util(struct rq *rq, 
unsigned int flags) {}
 #endif /* CONFIG_CPU_FREQ */
 
 #ifdef CONFIG_UCLAMP_TASK
-static inline unsigned int uclamp_util(struct rq *rq, unsigned int util)
+unsigned int uclamp_eff_value(struct task_struct *p, unsigned int clamp_id);
+
+static __always_inline
+unsigned int uclamp_util_with(struct rq *rq, unsigned int util,
+                             struct task_struct *p)
 {
        unsigned int min_util = READ_ONCE(rq->uclamp[UCLAMP_MIN].value);
        unsigned int max_util = READ_ONCE(rq->uclamp[UCLAMP_MAX].value);
 
+       if (p) {
+               min_util = max(min_util, uclamp_eff_value(p, UCLAMP_MIN));
+               max_util = max(max_util, uclamp_eff_value(p, UCLAMP_MAX));
+       }
+
        /*
         * Since CPU's {min,max}_util clamps are MAX aggregated considering
         * RUNNABLE tasks with _different_ clamps, we can end up with an
@@ -2291,7 +2300,17 @@ static inline unsigned int uclamp_util(struct rq *rq, 
unsigned int util)
 
        return clamp(util, min_util, max_util);
 }
+
+static inline unsigned int uclamp_util(struct rq *rq, unsigned int util)
+{
+       return uclamp_util_with(rq, util, NULL);
+}
 #else /* CONFIG_UCLAMP_TASK */
+static inline unsigned int uclamp_util_with(struct rq *rq, unsigned int util,
+                                           struct task_struct *p)
+{
+       return util;
+}
 static inline unsigned int uclamp_util(struct rq *rq, unsigned int util)
 {
        return util;
-- 
2.20.1