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Subject[PATCH v10 3/7] sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()
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From: Dietmar Eggemann <dietmar.eggemann@arm.com>

effective_cpu_util() already has a `int cpu' parameter which allows to
retrieve the CPU capacity scale factor (or maximum CPU capacity) inside
this function via an arch_scale_cpu_capacity(cpu).

A lot of code calling effective_cpu_util() (or the shim
sched_cpu_util()) needs the maximum CPU capacity, i.e. it will call
arch_scale_cpu_capacity() already.
But not having to pass it into effective_cpu_util() will make the EAS
wake-up code easier, especially when the maximum CPU capacity reduced
by the thermal pressure is passed through the EAS wake-up functions.

Due to the asymmetric CPU capacity support of arm/arm64 architectures,
arch_scale_cpu_capacity(int cpu) is a per-CPU variable read access via
per_cpu(cpu_scale, cpu) on such a system.
On all other architectures it is a a compile-time constant
(SCHED_CAPACITY_SCALE).

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
index f5eced0842b3..6a88eb7e9f75 100644
--- a/drivers/powercap/dtpm_cpu.c
+++ b/drivers/powercap/dtpm_cpu.c
@@ -71,34 +71,19 @@ static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)

static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
{
- unsigned long max = 0, sum_util = 0;
+ unsigned long max, sum_util = 0;
int cpu;

- for_each_cpu_and(cpu, pd_mask, cpu_online_mask) {
-
- /*
- * The capacity is the same for all CPUs belonging to
- * the same perf domain, so a single call to
- * arch_scale_cpu_capacity() is enough. However, we
- * need the CPU parameter to be initialized by the
- * loop, so the call ends up in this block.
- *
- * We can initialize 'max' with a cpumask_first() call
- * before the loop but the bits computation is not
- * worth given the arch_scale_cpu_capacity() just
- * returns a value where the resulting assembly code
- * will be optimized by the compiler.
- */
- max = arch_scale_cpu_capacity(cpu);
- sum_util += sched_cpu_util(cpu, max);
- }
-
/*
- * In the improbable case where all the CPUs of the perf
- * domain are offline, 'max' will be zero and will lead to an
- * illegal operation with a zero division.
+ * The capacity is the same for all CPUs belonging to
+ * the same perf domain.
*/
- return max ? (power * ((sum_util << 10) / max)) >> 10 : 0;
+ max = arch_scale_cpu_capacity(cpumask_first(pd_mask));
+
+ for_each_cpu_and(cpu, pd_mask, cpu_online_mask)
+ sum_util += sched_cpu_util(cpu);
+
+ return (power * ((sum_util << 10) / max)) >> 10;
}

static u64 get_pd_power_uw(struct dtpm *dtpm)
diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
index b8151d95a806..b263b0fde03c 100644
--- a/drivers/thermal/cpufreq_cooling.c
+++ b/drivers/thermal/cpufreq_cooling.c
@@ -137,11 +137,9 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
int cpu_idx)
{
- unsigned long max = arch_scale_cpu_capacity(cpu);
- unsigned long util;
+ unsigned long util = sched_cpu_util(cpu);

- util = sched_cpu_util(cpu, max);
- return (util * 100) / max;
+ return (util * 100) / arch_scale_cpu_capacity(cpu);
}
#else /* !CONFIG_SMP */
static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
diff --git a/include/linux/sched.h b/include/linux/sched.h
index c46f3a63b758..88b8817b827d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -2257,7 +2257,7 @@ static inline bool owner_on_cpu(struct task_struct *owner)
}

/* Returns effective CPU energy utilization, as seen by the scheduler */
-unsigned long sched_cpu_util(int cpu, unsigned long max);
+unsigned long sched_cpu_util(int cpu);
#endif /* CONFIG_SMP */

#ifdef CONFIG_RSEQ
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 53596842f0d8..c531976ee960 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7107,12 +7107,14 @@ struct task_struct *idle_task(int cpu)
* required to meet deadlines.
*/
unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
- unsigned long max, enum cpu_util_type type,
+ enum cpu_util_type type,
struct task_struct *p)
{
- unsigned long dl_util, util, irq;
+ unsigned long dl_util, util, irq, max;
struct rq *rq = cpu_rq(cpu);

+ max = arch_scale_cpu_capacity(cpu);
+
if (!uclamp_is_used() &&
type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
return max;
@@ -7192,10 +7194,9 @@ unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
return min(max, util);
}

-unsigned long sched_cpu_util(int cpu, unsigned long max)
+unsigned long sched_cpu_util(int cpu)
{
- return effective_cpu_util(cpu, cpu_util_cfs(cpu), max,
- ENERGY_UTIL, NULL);
+ return effective_cpu_util(cpu, cpu_util_cfs(cpu), ENERGY_UTIL, NULL);
}
#endif /* CONFIG_SMP */

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 3dbf351d12d5..1207c78f85c1 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -157,11 +157,10 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
static void sugov_get_util(struct sugov_cpu *sg_cpu)
{
struct rq *rq = cpu_rq(sg_cpu->cpu);
- unsigned long max = arch_scale_cpu_capacity(sg_cpu->cpu);

- sg_cpu->max = max;
+ sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu);
sg_cpu->bw_dl = cpu_bw_dl(rq);
- sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu), max,
+ sg_cpu->util = effective_cpu_util(sg_cpu->cpu, cpu_util_cfs(sg_cpu->cpu),
FREQUENCY_UTIL, NULL);
}

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 77f3eb1bf624..f87ff939cbf3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6704,12 +6704,11 @@ static long
compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd)
{
struct cpumask *pd_mask = perf_domain_span(pd);
- unsigned long cpu_cap = arch_scale_cpu_capacity(cpumask_first(pd_mask));
- unsigned long max_util = 0, sum_util = 0;
- unsigned long _cpu_cap = cpu_cap;
+ unsigned long max_util = 0, sum_util = 0, cpu_cap;
int cpu;

- _cpu_cap -= arch_scale_thermal_pressure(cpumask_first(pd_mask));
+ cpu_cap = arch_scale_cpu_capacity(cpumask_first(pd_mask));
+ cpu_cap -= arch_scale_thermal_pressure(cpumask_first(pd_mask));

/*
* The capacity state of CPUs of the current rd can be driven by CPUs
@@ -6746,10 +6745,10 @@ compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd)
* is already enough to scale the EM reported power
* consumption at the (eventually clamped) cpu_capacity.
*/
- cpu_util = effective_cpu_util(cpu, util_running, cpu_cap,
- ENERGY_UTIL, NULL);
+ cpu_util = effective_cpu_util(cpu, util_running, ENERGY_UTIL,
+ NULL);

- sum_util += min(cpu_util, _cpu_cap);
+ sum_util += min(cpu_util, cpu_cap);

/*
* Performance domain frequency: utilization clamping
@@ -6758,12 +6757,12 @@ compute_energy(struct task_struct *p, int dst_cpu, struct perf_domain *pd)
* NOTE: in case RT tasks are running, by default the
* FREQUENCY_UTIL's utilization can be max OPP.
*/
- cpu_util = effective_cpu_util(cpu, util_freq, cpu_cap,
- FREQUENCY_UTIL, tsk);
- max_util = max(max_util, min(cpu_util, _cpu_cap));
+ cpu_util = effective_cpu_util(cpu, util_freq, FREQUENCY_UTIL,
+ tsk);
+ max_util = max(max_util, min(cpu_util, cpu_cap));
}

- return em_cpu_energy(pd->em_pd, max_util, sum_util, _cpu_cap);
+ return em_cpu_energy(pd->em_pd, max_util, sum_util, cpu_cap);
}

/*
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index de5c99bea7be..287f0b06d4dd 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2895,7 +2895,7 @@ enum cpu_util_type {
};

unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
- unsigned long max, enum cpu_util_type type,
+ enum cpu_util_type type,
struct task_struct *p);

static inline unsigned long cpu_bw_dl(struct rq *rq)
--
2.36.1.255.ge46751e96f-goog
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