[PATCH V7 5/6] cpufreq: Restart governor as soon as possible
From: Viresh Kumar <viresh.kumar@linaro.org>
Date: 2015-06-08 12:56:11
Subsystem:
cpu frequency scaling framework, the rest · Maintainers:
"Rafael J. Wysocki", Viresh Kumar, Linus Torvalds
On cpu hot-unplug, we don't need to wait for POST_DEAD notification to restart the governor if the policy has atleast one online cpu left. We can restart the governor right from the DOWN_PREPARE notification instead. [ Something similar attempted by Saravana earlier ] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> --- drivers/cpufreq/cpufreq.c | 59 +++++++++++++++++++++-------------------------- 1 file changed, 26 insertions(+), 33 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index d3bd85263643..5f1c3366fb8e 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c@@ -1431,8 +1431,8 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) static int __cpufreq_remove_dev_prepare(struct device *dev, struct subsys_interface *sif) { - unsigned int cpu = dev->id, cpus; - int ret; + unsigned int cpu = dev->id; + int ret = 0; struct cpufreq_policy *policy; pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
@@ -1452,23 +1452,33 @@ static int __cpufreq_remove_dev_prepare(struct device *dev, } down_write(&policy->rwsem); - cpus = cpumask_weight(policy->cpus); + cpumask_clear_cpu(cpu, policy->cpus); - if (has_target() && cpus == 1) - strncpy(policy->last_governor, policy->governor->name, - CPUFREQ_NAME_LEN); + if (policy_is_inactive(policy)) { + if (has_target()) + strncpy(policy->last_governor, policy->governor->name, + CPUFREQ_NAME_LEN); + } else if (cpu == policy->cpu) { + /* Nominate new CPU */ + policy->cpu = cpumask_any(policy->cpus); + } up_write(&policy->rwsem); - if (cpu != policy->cpu) - return 0; + /* Start governor again for active policy */ + if (!policy_is_inactive(policy)) { + if (has_target()) { + ret = __cpufreq_governor(policy, CPUFREQ_GOV_START); + if (!ret) + ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); - if (cpus > 1) - /* Nominate new CPU */ - update_policy_cpu(policy, cpumask_any_but(policy->cpus, cpu)); - else if (cpufreq_driver->stop_cpu) + if (ret) + pr_err("%s: Failed to start governor\n", __func__); + } + } else if (cpufreq_driver->stop_cpu) { cpufreq_driver->stop_cpu(policy); + } - return 0; + return ret; } static int __cpufreq_remove_dev_finish(struct device *dev,
@@ -1476,33 +1486,16 @@ static int __cpufreq_remove_dev_finish(struct device *dev, { unsigned int cpu = dev->id; int ret; - struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); + struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu); if (!policy) { pr_debug("%s: No cpu_data found\n", __func__); return -EINVAL; } - down_write(&policy->rwsem); - cpumask_clear_cpu(cpu, policy->cpus); - up_write(&policy->rwsem); - - /* Not the last cpu of policy, start governor again ? */ - if (!policy_is_inactive(policy)) { - if (!has_target()) - return 0; - - ret = __cpufreq_governor(policy, CPUFREQ_GOV_START); - if (!ret) - ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS); - - if (ret) { - pr_err("%s: Failed to start governor\n", __func__); - return ret; - } - + /* Only proceed for inactive policies */ + if (!policy_is_inactive(policy)) return 0; - } /* If cpu is last user of policy, free policy */ if (has_target()) {
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2.4.0