mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-28 07:04:00 +08:00
62d6ae880e
There are two cpuidle governors ladder and menu. While the ladder governor is always available, if CONFIG_CPU_IDLE is selected, the menu governor additionally requires CONFIG_NO_HZ. A particular C state can be disabled by writing to the sysfs file /sys/devices/system/cpu/cpuN/cpuidle/stateN/disable, but this mechanism is only implemented in the menu governor. Thus, in a system where CONFIG_NO_HZ is not selected, the ladder governor becomes default and always will walk through all sleep states - irrespective of whether the C state was disabled via sysfs or not. The only way to select a specific C state was to write the related latency to /dev/cpu_dma_latency and keep the file open as long as this setting was required - not very practical and not suitable for setting a single core in an SMP system. With this patch, the ladder governor only will promote to the next C state, if it has not been disabled, and it will demote, if the current C state was disabled. Note that the patch does not make the setting of the sysfs variable "disable" coherent, i.e. if one is disabling a light state, then all deeper states are disabled as well, but the "disable" variable does not reflect it. Likewise, if one enables a deep state but a lighter state still is disabled, then this has no effect. A related section has been added to the documentation. Signed-off-by: Carsten Emde <C.Emde@osadl.org> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
93 lines
3.4 KiB
Plaintext
93 lines
3.4 KiB
Plaintext
|
|
|
|
Supporting multiple CPU idle levels in kernel
|
|
|
|
cpuidle sysfs
|
|
|
|
System global cpuidle related information and tunables are under
|
|
/sys/devices/system/cpu/cpuidle
|
|
|
|
The current interfaces in this directory has self-explanatory names:
|
|
* current_driver
|
|
* current_governor_ro
|
|
|
|
With cpuidle_sysfs_switch boot option (meant for developer testing)
|
|
following objects are visible instead.
|
|
* current_driver
|
|
* available_governors
|
|
* current_governor
|
|
In this case users can switch the governor at run time by writing
|
|
to current_governor.
|
|
|
|
|
|
Per logical CPU specific cpuidle information are under
|
|
/sys/devices/system/cpu/cpuX/cpuidle
|
|
for each online cpu X
|
|
|
|
--------------------------------------------------------------------------------
|
|
# ls -lR /sys/devices/system/cpu/cpu0/cpuidle/
|
|
/sys/devices/system/cpu/cpu0/cpuidle/:
|
|
total 0
|
|
drwxr-xr-x 2 root root 0 Feb 8 10:42 state0
|
|
drwxr-xr-x 2 root root 0 Feb 8 10:42 state1
|
|
drwxr-xr-x 2 root root 0 Feb 8 10:42 state2
|
|
drwxr-xr-x 2 root root 0 Feb 8 10:42 state3
|
|
|
|
/sys/devices/system/cpu/cpu0/cpuidle/state0:
|
|
total 0
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
|
|
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 time
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
|
|
|
|
/sys/devices/system/cpu/cpu0/cpuidle/state1:
|
|
total 0
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
|
|
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 time
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
|
|
|
|
/sys/devices/system/cpu/cpu0/cpuidle/state2:
|
|
total 0
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
|
|
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 time
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
|
|
|
|
/sys/devices/system/cpu/cpu0/cpuidle/state3:
|
|
total 0
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 desc
|
|
-rw-r--r-- 1 root root 4096 Feb 8 10:42 disable
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 latency
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 name
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 power
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 time
|
|
-r--r--r-- 1 root root 4096 Feb 8 10:42 usage
|
|
--------------------------------------------------------------------------------
|
|
|
|
|
|
* desc : Small description about the idle state (string)
|
|
* disable : Option to disable this idle state (bool) -> see note below
|
|
* latency : Latency to exit out of this idle state (in microseconds)
|
|
* name : Name of the idle state (string)
|
|
* power : Power consumed while in this idle state (in milliwatts)
|
|
* time : Total time spent in this idle state (in microseconds)
|
|
* usage : Number of times this state was entered (count)
|
|
|
|
Note:
|
|
The behavior and the effect of the disable variable depends on the
|
|
implementation of a particular governor. In the ladder governor, for
|
|
example, it is not coherent, i.e. if one is disabling a light state,
|
|
then all deeper states are disabled as well, but the disable variable
|
|
does not reflect it. Likewise, if one enables a deep state but a lighter
|
|
state still is disabled, then this has no effect.
|