Hi Nathan,
Welcome back :)
On 1 April 2013 21:03, Nathan Zimmer <nzimmer@xxxxxxx> wrote:
You need to resent this patch as we don't want current mail subject as commit
subject.. You could have used the area after three dashes "-" inside the
commit for logs which you don't want to commit.
> The cpufreq_driver_lock is hot with some configs.
> This lock covers both cpufreq_driver and cpufreq_cpu_data so part one of the
s/ so/, so/
> proposed fix is to split up the lock abit.
s/abit/a bit/
What's the other part?
> cpufreq_cpu_data is now covered by the cpufreq_data_lock.
> cpufreq_driver is now covered by the cpufreq_driver lock and the rcu.
>
> This means that the cpufreq_driver_lock is no longer hot.
> There remains some measurable heat on the cpufreq_data_lock it is significantly
s/it/but it/
> less then previous measured though.
>
> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
> Signed-off-by: Nathan Zimmer <nzimmer@xxxxxxx>
> ---
> drivers/cpufreq/cpufreq.c | 305 +++++++++++++++++++++++++++++++++-------------
> 1 file changed, 222 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> @@ -329,11 +339,23 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
> struct cpufreq_governor **governor)
> {
> int err = -EINVAL;
> -
> - if (!cpufreq_driver)
> + struct cpufreq_driver *driver;
> + int (*setpolicy)(struct cpufreq_policy *policy);
> + int (*target)(struct cpufreq_policy *policy,
> + unsigned int target_freq,
> + unsigned int relation);
You can keep bools here instead of complex function pointers.
setpolicy_supported and target_supported
> + rcu_read_lock();
> + driver = rcu_dereference(cpufreq_driver);
> + if (!driver) {
> + rcu_read_unlock();
> goto out;
> + }
> + setpolicy = driver->setpolicy;
> + target = driver->target;
> + rcu_read_unlock();
>
> - if (cpufreq_driver->setpolicy) {
> + if (setpolicy) {
> if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
> *policy = CPUFREQ_POLICY_PERFORMANCE;
> err = 0;
> @@ -342,7 +364,7 @@ static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
> *policy = CPUFREQ_POLICY_POWERSAVE;
> err = 0;
> }
> - } else if (cpufreq_driver->target) {
> + } else if (target) {
> struct cpufreq_governor *t;
>
> mutex_lock(&cpufreq_governor_mutex);
> @@ -731,6 +766,8 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
> {
> struct cpufreq_policy new_policy;
> struct freq_attr **drv_attr;
> + struct cpufreq_driver *driver;
> + int (*exit)(struct cpufreq_policy *policy);
Declare it in the block which used it.
> if (ret) {
> pr_debug("setting policy failed\n");
> - if (cpufreq_driver->exit)
> - cpufreq_driver->exit(policy);
> + rcu_read_lock();
> + exit = rcu_dereference(cpufreq_driver)->exit;
> + if (exit)
> + exit(policy);
> + rcu_read_unlock();
> +
> }
> @@ -1002,32 +1059,42 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
> unsigned int cpu = dev->id, ret, cpus;
> unsigned long flags;
> struct cpufreq_policy *data;
> + struct cpufreq_driver *driver;
> struct kobject *kobj;
> struct completion *cmp;
> struct device *cpu_dev;
> + int (*target)(struct cpufreq_policy *policy,
> + unsigned int target_freq,
> + unsigned int relation);
can be bool?
> + int (*exit)(struct cpufreq_policy *policy);
>
One more generic comment: What about a reader-writer lock for
cpufreq_data_lock??
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