The discussion about having different cpus on the system with different latencies bring us to a first attemp by adding a pointer in the cpuidle_device to the states array.
But as Rafael suggested, it would make more sense to create a driver per cpu [1].
This patch add support for multiple cpuidle drivers and as Rafael expected, it had less impact than the first approach and is much more clean.
It creates a per cpu cpuidle driver pointer. In order to not break the different drivers, the function cpuidle_register_driver assign for each cpu, the driver.
If this patch is accepted, I will add a cpuidle_register_cpu_driver and modify the cpuidle drivers to make use of it and then remove the cpuidle_register_driver.
Note the output of sysfs for "/sys/devices/system/cpu/cpuidle/current_driver" has been changed and instead of showing a single driver name, it shows the cpu and the associated driver name.
[1] http://www.spinics.net/lists/linux-acpi/msg37921.html
Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org --- drivers/cpuidle/driver.c | 62 +++++++++++++++++++++++++++++++--------------- drivers/cpuidle/sysfs.c | 28 ++++++++++++++++---- include/linux/cpuidle.h | 1 + 3 files changed, 65 insertions(+), 26 deletions(-)
diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c index 676febd..b2f8823 100644 --- a/drivers/cpuidle/driver.c +++ b/drivers/cpuidle/driver.c @@ -11,10 +11,11 @@ #include <linux/mutex.h> #include <linux/module.h> #include <linux/cpuidle.h> +#include <linux/smp.h>
#include "cpuidle.h"
-static struct cpuidle_driver *cpuidle_curr_driver; +DEFINE_PER_CPU(struct cpuidle_driver *, cpuidle_drivers); DEFINE_SPINLOCK(cpuidle_driver_lock);
static void set_power_states(struct cpuidle_driver *drv) @@ -45,6 +46,8 @@ static void set_power_states(struct cpuidle_driver *drv) */ int cpuidle_register_driver(struct cpuidle_driver *drv) { + int cpu, ret, i; + if (!drv || !drv->state_count) return -EINVAL;
@@ -52,28 +55,44 @@ int cpuidle_register_driver(struct cpuidle_driver *drv) return -ENODEV;
spin_lock(&cpuidle_driver_lock); - if (cpuidle_curr_driver) { - spin_unlock(&cpuidle_driver_lock); - return -EBUSY; - } - - if (!drv->power_specified) - set_power_states(drv); + ret = -EBUSY; + for_each_present_cpu(cpu) { + if (per_cpu(cpuidle_drivers, cpu)) + goto unregister;
- cpuidle_curr_driver = drv; + if (!drv->power_specified) + set_power_states(drv);
+ per_cpu(cpuidle_drivers, cpu) = drv; + } + ret = 0; +out: spin_unlock(&cpuidle_driver_lock); + return ret;
- return 0; +unregister: + for (i = cpu; i >= 0; i--) + per_cpu(cpuidle_drivers, i) = NULL; + goto out; } EXPORT_SYMBOL_GPL(cpuidle_register_driver);
/** + * cpuidle_get_cpu_driver - return the driver tied with the cpu + * @cpu : the cpu number + */ +struct cpuidle_driver *cpuidle_get_cpu_driver(int cpu) +{ + return per_cpu(cpuidle_drivers, cpu); +} +EXPORT_SYMBOL_GPL(cpuidle_get_cpu_driver); + +/** * cpuidle_get_driver - return the current driver */ struct cpuidle_driver *cpuidle_get_driver(void) { - return cpuidle_curr_driver; + return cpuidle_get_cpu_driver(smp_processor_id()); } EXPORT_SYMBOL_GPL(cpuidle_get_driver);
@@ -83,17 +102,20 @@ EXPORT_SYMBOL_GPL(cpuidle_get_driver); */ void cpuidle_unregister_driver(struct cpuidle_driver *drv) { - if (drv != cpuidle_curr_driver) { - WARN(1, "invalid cpuidle_unregister_driver(%s)\n", - drv->name); - return; - } + int cpu; + struct cpuidle_driver *d;
spin_lock(&cpuidle_driver_lock); + for_each_present_cpu(cpu) { + + d = per_cpu(cpuidle_drivers, cpu); + if (drv != d) + continue;
- if (!WARN_ON(drv->refcnt > 0)) - cpuidle_curr_driver = NULL; + if (!WARN_ON(drv->refcnt > 0)) + per_cpu(cpuidle_drivers, cpu) = NULL;
+ } spin_unlock(&cpuidle_driver_lock); } EXPORT_SYMBOL_GPL(cpuidle_unregister_driver); @@ -104,7 +126,7 @@ struct cpuidle_driver *cpuidle_driver_ref(void)
spin_lock(&cpuidle_driver_lock);
- drv = cpuidle_curr_driver; + drv = cpuidle_get_driver(); drv->refcnt++;
spin_unlock(&cpuidle_driver_lock); @@ -113,7 +135,7 @@ struct cpuidle_driver *cpuidle_driver_ref(void)
void cpuidle_driver_unref(void) { - struct cpuidle_driver *drv = cpuidle_curr_driver; + struct cpuidle_driver *drv = cpuidle_get_driver();
spin_lock(&cpuidle_driver_lock);
diff --git a/drivers/cpuidle/sysfs.c b/drivers/cpuidle/sysfs.c index 5f809e3..05abebe 100644 --- a/drivers/cpuidle/sysfs.c +++ b/drivers/cpuidle/sysfs.c @@ -47,14 +47,30 @@ static ssize_t show_current_driver(struct device *dev, struct device_attribute *attr, char *buf) { - ssize_t ret; - struct cpuidle_driver *cpuidle_driver = cpuidle_get_driver(); + int cpu; + ssize_t ret, count = 0; + struct cpuidle_driver *drv;
spin_lock(&cpuidle_driver_lock); - if (cpuidle_driver) - ret = sprintf(buf, "%s\n", cpuidle_driver->name); - else - ret = sprintf(buf, "none\n"); + for_each_online_cpu(cpu) { + + drv = cpuidle_get_cpu_driver(cpu); + + ret = -EOVERFLOW; + if ((drv && (strlen(drv->name) + count) >= PAGE_SIZE) || + (!drv && (strlen("none") + count) >= PAGE_SIZE)) + goto out; + + ret = sprintf(buf + count, "cpu%d: %s\n", + cpu, drv ? drv->name : "none" ); + + if (ret < 0) + goto out; + + count += ret; + } + ret = count; +out: spin_unlock(&cpuidle_driver_lock);
return ret; diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h index a4ff9f8..ab6a3ed 100644 --- a/include/linux/cpuidle.h +++ b/include/linux/cpuidle.h @@ -146,6 +146,7 @@ extern void disable_cpuidle(void); extern int cpuidle_idle_call(void); extern int cpuidle_register_driver(struct cpuidle_driver *drv); extern struct cpuidle_driver *cpuidle_get_driver(void); +extern struct cpuidle_driver *cpuidle_get_cpu_driver(int cpu); extern struct cpuidle_driver *cpuidle_driver_ref(void); extern void cpuidle_driver_unref(void); extern void cpuidle_unregister_driver(struct cpuidle_driver *drv);