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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>
This commit is contained in:
Patrick Bellasi 2019-06-21 09:42:11 +01:00 committed by Ingo Molnar
parent 982d9cdc22
commit 9d20ad7dfc
2 changed files with 33 additions and 1 deletions
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13
kernel/sched/core.c
View File

@ -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

21
kernel/sched/sched.h
View File

@ -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;