sched, drivers: Remove max param from effective_cpu_util()/sched_cpu_util()

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>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Link: https://lkml.kernel.org/r/20220621090414.433602-4-vdonnefort@google.com

diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
index f5eced0..6a88eb7 100644 (file)
--- 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 b8151d9..b263b0f 100644 (file)
--- 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 c46f3a6..88b8817 100644 (file)
--- 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 d3e2c5a..c538a0a 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7125,12 +7125,14 @@ 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;
@@ -7210,10 +7212,9 @@ 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 3dbf351..1207c78 100644 (file)
--- 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 80be1f1..6de09b2 100644 (file)
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6712,12 +6712,11 @@ 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
@@ -6754,10 +6753,10 @@ 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
@@ -6766,12 +6765,12 @@ 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 76b0027..73ae328 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2886,7 +2886,7 @@ 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)