[PATCH v2 1/2] cpufreq: schedutil: Introduce single max CPU capacity for freqency domain

From: Lukasz Luba
Date: Wed Dec 07 2022 - 05:17:55 EST


Prepare the code for optimizations and move the max CPU capacity
into the sugov_policy struct. This will allow to leverage the fact that
the max CPU capacity is the same for all CPUs in the frequency domain.

Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx>
---
kernel/sched/cpufreq_schedutil.c | 17 ++++++++++++-----
1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 1207c78f85c1..c19d6de67b7a 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -25,6 +25,9 @@ struct sugov_policy {
unsigned int next_freq;
unsigned int cached_raw_freq;

+ /* max CPU capacity, which is equal for all CPUs in freq. domain */
+ unsigned long max;
+
/* The next fields are only needed if fast switch cannot be used: */
struct irq_work irq_work;
struct kthread_work work;
@@ -48,7 +51,6 @@ struct sugov_cpu {

unsigned long util;
unsigned long bw_dl;
- unsigned long max;

/* The field below is for single-CPU policies only: */
#ifdef CONFIG_NO_HZ_COMMON
@@ -156,9 +158,10 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,

static void sugov_get_util(struct sugov_cpu *sg_cpu)
{
+ struct sugov_policy *sg_policy = sg_cpu->sg_policy;
struct rq *rq = cpu_rq(sg_cpu->cpu);

- sg_cpu->max = arch_scale_cpu_capacity(sg_cpu->cpu);
+ sg_policy->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),
FREQUENCY_UTIL, NULL);
@@ -253,6 +256,7 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
*/
static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
{
+ struct sugov_policy *sg_policy = sg_cpu->sg_policy;
unsigned long boost;

/* No boost currently required */
@@ -280,7 +284,8 @@ static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time)
* sg_cpu->util is already in capacity scale; convert iowait_boost
* into the same scale so we can compare.
*/
- boost = (sg_cpu->iowait_boost * sg_cpu->max) >> SCHED_CAPACITY_SHIFT;
+ boost = sg_cpu->iowait_boost * sg_policy->max;
+ boost >>= SCHED_CAPACITY_SHIFT;
boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);
if (sg_cpu->util < boost)
sg_cpu->util = boost;
@@ -337,7 +342,7 @@ static void sugov_update_single_freq(struct update_util_data *hook, u64 time,
if (!sugov_update_single_common(sg_cpu, time, flags))
return;

- next_f = get_next_freq(sg_policy, sg_cpu->util, sg_cpu->max);
+ next_f = get_next_freq(sg_policy, sg_cpu->util, sg_policy->max);
/*
* Do not reduce the frequency if the CPU has not been idle
* recently, as the reduction is likely to be premature then.
@@ -373,6 +378,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
unsigned int flags)
{
struct sugov_cpu *sg_cpu = container_of(hook, struct sugov_cpu, update_util);
+ struct sugov_policy *sg_policy = sg_cpu->sg_policy;
unsigned long prev_util = sg_cpu->util;

/*
@@ -399,7 +405,7 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
sg_cpu->util = prev_util;

cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
- map_util_perf(sg_cpu->util), sg_cpu->max);
+ map_util_perf(sg_cpu->util), sg_policy->max);

sg_cpu->sg_policy->last_freq_update_time = time;
}
@@ -760,6 +766,7 @@ static int sugov_start(struct cpufreq_policy *policy)
sg_policy->work_in_progress = false;
sg_policy->limits_changed = false;
sg_policy->cached_raw_freq = 0;
+ sg_policy->max = 0;

sg_policy->need_freq_update = cpufreq_driver_test_flags(CPUFREQ_NEED_UPDATE_LIMITS);

--
2.17.1