cpuidle take2: Basic documentation for cpuidle
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PATCH 3/3 cpuidle take2: Basic documentation for cpuidle
Documentation for cpuidle infrastructure
Signed-off-by Venkatesh Pallipadi <[email protected]>
Signed-off-by Adam Belay <[email protected]>
Signed-off-by Shaohua Li <[email protected]>
Documentation/cpuidle/core.txt new file +17 -0
@@ -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. + +
Documentation/cpuidle/driver.txt new file +24 -0
@@ -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);
Documentation/cpuidle/sysfs.txt new file +27 -0
@@ -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 + +
Documentation/cpuidle/governor.txt new file +24 -0
@@ -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); +
Hi!
Quoted 16 lines
Documentation for cpuidle infrastructure
Signed-off-by Venkatesh Pallipadi <[email protected]>Signed-off-by Adam Belay <[email protected]>Signed-off-by Shaohua Li <[email protected]>Index:
linux-2.6.21-rc-mm/Documentation/cpuidle/core.txt
===================================================================Documentation/cpuidle/core.txt new file +5
-0@@ -0,0 +1,17 @@ + + Supporting multiple CPU idle levels in kernel + + cpuidle +
Documentation/cpuidle/core.txt line 15
Quoted 10 lines
Documentation/cpuidle/core.txt new file +10
-0+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.
Drop leading slash? Merge this to some other docs, since it is so short?
Quoted 8 lines
Index:
linux-2.6.21-rc-mm/Documentation/cpuidle/driver.txt
===================================================================Documentation/cpuidle/driver.txt new file +3
-0@@ -0,0 +1,24 @@ + + + Supporting multiple CPU idle levels in kernel
Documentation/cpuidle/driver.txt line 13
Quoted 10 lines
Documentation/cpuidle/driver.txt new file +10
-0+ + 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.
Huh, perhaps it would be nice to explain what the driver does?
Now we know that it does...
Documentation/cpuidle/driver.txt line 24
Quoted 10 lines
Documentation/cpuidle/driver.txt new file +10
-0+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);
register, unregister and redetect... but that somehow does not seem complete?
Documentation/cpuidle/sysfs.txt line 8
Quoted 13 lines
Index:
linux-2.6.21-rc-mm/Documentation/cpuidle/sysfs.txt
===================================================================Documentation/cpuidle/sysfs.txt new file +8
-0@@ -0,0 +1,27 @@ + + + Supporting multiple CPU idle levels in kernel + + cpuidle sysfs + +System global cpuidle information are under +/sys/devices/system/cpu/cpuidle
"information is"? (Not 100% sure).
Documentation/cpuidle/sysfs.txt line 25
Quoted 6 lines
Documentation/cpuidle/sysfs.txt new file +6
-0+Under this percpu directory, there is a directory for each idle state supported +by the driver, which in turn has +* latency +* power +* time +* usage
This should say... latency (in microseconds), power (in miliwats), and explain what time (which units?) and usage means. (Total time spent in that state, usage == number of enters into that state?)
Documentation/cpuidle/sysfs.txt line 25
Quoted 11 lines
Documentation/cpuidle/sysfs.txt new file +11
-0+ 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
Can we get some visual separation between functions and their descriptions?
scan() callback?
scan -- callback?
Documentation/cpuidle/sysfs.txt line 27
Quoted 2 lines
Documentation/cpuidle/sysfs.txt new file +2
-0+More than one governor can be registered at the same time and +user can switch between drivers using /sysfs interface.
<describe interface here>?
Explain why we want more than one governor?
Pavel
Signature · 2 lines
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