sched/uclamp: Add uclamp_util_with()

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.bellasi@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alessio Balsini <balsini@android.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Perret <quentin.perret@arm.com>
Cc: Rafael J . Wysocki <rafael.j.wysocki@intel.com>
Cc: Steve Muckle <smuckle@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Todd Kjos <tkjos@google.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Link: https://lkml.kernel.org/r/20190621084217.8167-11-patrick.bellasi@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 6cd5133f0c2a3490188c94553fcca18104a48592..fa43ce3962e7959f94ea17fed65de41c91d0d0a8 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -880,6 +880,19 @@ uclamp_eff_get(struct task_struct *p, unsigned int clamp_id)
        return uc_req;
 }
 
+unsigned int uclamp_eff_value(struct task_struct *p, unsigned int clamp_id)
+{
+       struct uclamp_se uc_eff;
+
+       /* Task currently refcounted: use back-annotated (effective) value */
+       if (p->uclamp[clamp_id].active)
+               return p->uclamp[clamp_id].value;
+
+       uc_eff = uclamp_eff_get(p, clamp_id);
+
+       return uc_eff.value;
+}
+
 /*
  * When a task is enqueued on a rq, the clamp bucket currently defined by the
  * task's uclamp::bucket_id is refcounted on that rq. This also immediately

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 9b0c77a99346984d05b84dc0d697095dfb09fb7f..1783f6b4c2e094335118704cb33513eadf35a154 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2266,11 +2266,20 @@ 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
@@ -2281,7 +2290,17 @@ 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;