Hi! > 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. Drop leading slash? Merge this to some other docs, since it is so short? > 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. Huh, perhaps it would be nice to explain what the driver does? Now we know that it does... > +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? > 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 "information is"? (Not 100% sure). > +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?) > + 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? > +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 -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - 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
