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ANDROID: sched: Allow EAS without schedutil

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This effectively reverts 531b5c9f5c ("sched/topology: Make Energy
Aware Scheduling depend on schedutil"), and updates the documentation
accordingly.

In the context of GKI 2.0, some partners need to use a custom cpufreq
govenor, but would like to keep EAS enabled.

Remove the hard dependency between them.

Bug: 157580690
Signed-off-by: Quentin Perret <qperret@google.com>
Change-Id: Ied1c5aba6b692e26776b3e2c050780a67cc5bae1
This commit is contained in:
Quentin Perret 2020-06-05 09:06:50 +01:00
parent 0d70da26af
commit bdfa61448f
5 changed files with 1 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/scheduler/sched-energy.rst
View File

@ -405,7 +405,7 @@ Consequently, the only sane governor to use together with EAS is schedutil,
because it is the only one providing some degree of consistency between
frequency requests and energy predictions.
Using EAS with any other governor than schedutil is not supported.
Using EAS with any other governor than schedutil is not recommended.
6.5 Scale-invariant utilization signals

1
drivers/cpufreq/cpufreq.c
View File

@ -2472,7 +2472,6 @@ static int cpufreq_set_policy(struct cpufreq_policy *policy,
ret = cpufreq_start_governor(policy);
if (!ret) {
pr_debug("governor change\n");
sched_cpufreq_governor_change(policy, old_gov);
return 0;
}
cpufreq_exit_governor(policy);

8
include/linux/cpufreq.h
View File

@ -979,14 +979,6 @@ static inline bool policy_has_boost_freq(struct cpufreq_policy *policy)
}
#endif
#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
struct cpufreq_governor *old_gov);
#else
static inline void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
struct cpufreq_governor *old_gov) { }
#endif
extern void arch_freq_prepare_all(void);
extern unsigned int arch_freq_get_on_cpu(int cpu);

33
kernel/sched/cpufreq_schedutil.c
View File

@ -914,36 +914,3 @@ static int __init sugov_register(void)
return cpufreq_register_governor(&schedutil_gov);
}
core_initcall(sugov_register);
#ifdef CONFIG_ENERGY_MODEL
extern bool sched_energy_update;
extern struct mutex sched_energy_mutex;
static void rebuild_sd_workfn(struct work_struct *work)
{
mutex_lock(&sched_energy_mutex);
sched_energy_update = true;
rebuild_sched_domains();
sched_energy_update = false;
mutex_unlock(&sched_energy_mutex);
}
static DECLARE_WORK(rebuild_sd_work, rebuild_sd_workfn);
/*
* EAS shouldn't be attempted without sugov, so rebuild the sched_domains
* on governor changes to make sure the scheduler knows about it.
*/
void sched_cpufreq_governor_change(struct cpufreq_policy *policy,
struct cpufreq_governor *old_gov)
{
if (old_gov == &schedutil_gov || policy->governor == &schedutil_gov) {
/*
* When called from the cpufreq_register_driver() path, the
* cpu_hotplug_lock is already held, so use a work item to
* avoid nested locking in rebuild_sched_domains().
*/
schedule_work(&rebuild_sd_work);
}
}
#endif

17
kernel/sched/topology.c
View File

@ -319,7 +319,6 @@ static void sched_energy_set(bool has_eas)
* 2. the SD_ASYM_CPUCAPACITY flag is set in the sched_domain hierarchy.
* 3. no SMT is detected.
* 4. the EM complexity is low enough to keep scheduling overheads low;
* 5. schedutil is driving the frequency of all CPUs of the rd;
*
* The complexity of the Energy Model is defined as:
*
@ -339,15 +338,12 @@ static void sched_energy_set(bool has_eas)
*/
#define EM_MAX_COMPLEXITY 2048
extern struct cpufreq_governor schedutil_gov;
static bool build_perf_domains(const struct cpumask *cpu_map)
{
int i, nr_pd = 0, nr_cs = 0, nr_cpus = cpumask_weight(cpu_map);
struct perf_domain *pd = NULL, *tmp;
int cpu = cpumask_first(cpu_map);
struct root_domain *rd = cpu_rq(cpu)->rd;
struct cpufreq_policy *policy;
struct cpufreq_governor *gov;
if (!sysctl_sched_energy_aware)
goto free;
@ -373,19 +369,6 @@ static bool build_perf_domains(const struct cpumask *cpu_map)
if (find_pd(pd, i))
continue;
/* Do not attempt EAS if schedutil is not being used. */
policy = cpufreq_cpu_get(i);
if (!policy)
goto free;
gov = policy->governor;
cpufreq_cpu_put(policy);
if (gov != &schedutil_gov) {
if (rd->pd)
pr_warn("rd %*pbl: Disabling EAS, schedutil is mandatory\n",
cpumask_pr_args(cpu_map));
goto free;
}
/* Create the new pd and add it to the local list. */
tmp = pd_init(i);
if (!tmp)