On 09-06-15, 01:27, Rafael J. Wysocki wrote:
Any explanation why this is correct here?
Does this look better ? (Code isn't updated)
From: Viresh Kumar viresh.kumar@linaro.org Date: Thu, 19 Feb 2015 11:53:02 +0530 Subject: [PATCH] cpufreq: Restart governor as soon as possible
__cpufreq_remove_dev_finish() is doing two things today: - Restarts the governor if some CPUs from concerned policy are still online. - Frees the policy if all CPUs are offline.
The first task of restarting the governor can be moved to __cpufreq_remove_dev_prepare() to restart the governor early. There is no race between _prepare() and _finish() as they would be handling completely different cases. _finish() will only be required if we are going to free the policy and that has nothing to do with restarting the governor.
[ 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 8b810071ddd2..c355ab656dfb 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1428,8 +1428,8 @@ 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); @@ -1449,23 +1449,33 @@ 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, @@ -1473,33 +1483,16 @@ 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()) {