Documentation for cpuidle infrastructure Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@xxxxxxxxx> Signed-off-by: Adam Belay <abelay@xxxxxxxxxx> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx> Index: linux-2.6.21-rc-mm/Documentation/cpuidle/core.txt =================================================================== --- /dev/null +++ linux-2.6.21-rc-mm/Documentation/cpuidle/core.txt @@ -0,0 +1,17 @@ + + Supporting multiple CPU idle levels in kernel + + cpuidle + +General Information: + +Various CPUs today support multiple idle levels that are differentiated +by varying exit latencies and power consumption during idle. +cpuidle is a generic in-kernel infrastructure that separates +idle policy (governor) from idle mechanism (driver) and provides a +standardized infrastructure to support independent development of +governors and drivers. + +cpuidle resides under /drivers/cpuidle. + + Index: linux-2.6.21-rc-mm/Documentation/cpuidle/driver.txt =================================================================== --- /dev/null +++ linux-2.6.21-rc-mm/Documentation/cpuidle/driver.txt @@ -0,0 +1,24 @@ + + + Supporting multiple CPU idle levels in kernel + + cpuidle drivers + + + + +cpuidle driver supports capability detection for a particular system. The +init and exit routines will be called for each online CPU, with a percpu +cpuidle_driver object and driver should fill in cpuidle_states inside +cpuidle_driver depending on the CPU capability. + +Driver can handle dynamic state changes (like battery<->AC), by calling +force_redetect interface. + +It is possible to have more than one driver registered at the same time and +user can switch between drivers using /sysfs interface. + +Interfaces: +int cpuidle_register_driver(struct cpuidle_driver *drv); +void cpuidle_unregister_driver(struct cpuidle_driver *drv); +int cpuidle_force_redetect(struct cpuidle_device *dev); Index: linux-2.6.21-rc-mm/Documentation/cpuidle/sysfs.txt =================================================================== --- /dev/null +++ linux-2.6.21-rc-mm/Documentation/cpuidle/sysfs.txt @@ -0,0 +1,27 @@ + + + Supporting multiple CPU idle levels in kernel + + cpuidle sysfs + +System global cpuidle information are under +/sys/devices/system/cpu/cpuidle + +The current interfaces in this directory has self-explanatory names: +* available_drivers +* available_governors +* current_driver +* current_governor + +Per logical CPU specific cpuidle information are under +/sys/devices/system/cpu/cpuX/cpuidle +for each online cpu X + +Under this percpu directory, there is a directory for each idle state supported +by the driver, which in turn has +* latency +* power +* time +* usage + + Index: linux-2.6.21-rc-mm/Documentation/cpuidle/governor.txt =================================================================== --- /dev/null +++ linux-2.6.21-rc-mm/Documentation/cpuidle/governor.txt @@ -0,0 +1,24 @@ + + + + Supporting multiple CPU idle levels in kernel + + cpuidle governors + + + + +cpuidle governor is policy routine that decides what idle state to enter at +any given time. cpuidle core uses different callbacks to governor while +handling idle entry. +* select_state callback where governor can determine next idle state to enter +* prepare_idle callback is called before entering an idle state +* scan callback is called after a driver forces redetection of the states + +More than one governor can be registered at the same time and +user can switch between drivers using /sysfs interface. + +Interfaces: +int cpuidle_register_governor(struct cpuidle_governor *gov); +void cpuidle_unregister_governor(struct cpuidle_governor *gov); + - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
