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Documentation / cpuidle / sysfs.txt




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Based on kernel version 3.16. Page generated on 2014-08-06 21:36 EST.

1	
2	
3			Supporting multiple CPU idle levels in kernel
4	
5					cpuidle sysfs
6	
7	System global cpuidle related information and tunables are under
8	/sys/devices/system/cpu/cpuidle
9	
10	The current interfaces in this directory has self-explanatory names:
11	* current_driver
12	* current_governor_ro
13	
14	With cpuidle_sysfs_switch boot option (meant for developer testing)
15	following objects are visible instead.
16	* current_driver
17	* available_governors
18	* current_governor
19	In this case users can switch the governor at run time by writing
20	to current_governor.
21	
22	
23	Per logical CPU specific cpuidle information are under
24	/sys/devices/system/cpu/cpuX/cpuidle
25	for each online cpu X
26	
27	--------------------------------------------------------------------------------
28	# ls -lR /sys/devices/system/cpu/cpu0/cpuidle/
29	/sys/devices/system/cpu/cpu0/cpuidle/:
30	total 0
31	drwxr-xr-x 2 root root 0 Feb  8 10:42 state0
32	drwxr-xr-x 2 root root 0 Feb  8 10:42 state1
33	drwxr-xr-x 2 root root 0 Feb  8 10:42 state2
34	drwxr-xr-x 2 root root 0 Feb  8 10:42 state3
35	
36	/sys/devices/system/cpu/cpu0/cpuidle/state0:
37	total 0
38	-r--r--r-- 1 root root 4096 Feb  8 10:42 desc
39	-rw-r--r-- 1 root root 4096 Feb  8 10:42 disable
40	-r--r--r-- 1 root root 4096 Feb  8 10:42 latency
41	-r--r--r-- 1 root root 4096 Feb  8 10:42 name
42	-r--r--r-- 1 root root 4096 Feb  8 10:42 power
43	-r--r--r-- 1 root root 4096 Feb  8 10:42 time
44	-r--r--r-- 1 root root 4096 Feb  8 10:42 usage
45	
46	/sys/devices/system/cpu/cpu0/cpuidle/state1:
47	total 0
48	-r--r--r-- 1 root root 4096 Feb  8 10:42 desc
49	-rw-r--r-- 1 root root 4096 Feb  8 10:42 disable
50	-r--r--r-- 1 root root 4096 Feb  8 10:42 latency
51	-r--r--r-- 1 root root 4096 Feb  8 10:42 name
52	-r--r--r-- 1 root root 4096 Feb  8 10:42 power
53	-r--r--r-- 1 root root 4096 Feb  8 10:42 time
54	-r--r--r-- 1 root root 4096 Feb  8 10:42 usage
55	
56	/sys/devices/system/cpu/cpu0/cpuidle/state2:
57	total 0
58	-r--r--r-- 1 root root 4096 Feb  8 10:42 desc
59	-rw-r--r-- 1 root root 4096 Feb  8 10:42 disable
60	-r--r--r-- 1 root root 4096 Feb  8 10:42 latency
61	-r--r--r-- 1 root root 4096 Feb  8 10:42 name
62	-r--r--r-- 1 root root 4096 Feb  8 10:42 power
63	-r--r--r-- 1 root root 4096 Feb  8 10:42 time
64	-r--r--r-- 1 root root 4096 Feb  8 10:42 usage
65	
66	/sys/devices/system/cpu/cpu0/cpuidle/state3:
67	total 0
68	-r--r--r-- 1 root root 4096 Feb  8 10:42 desc
69	-rw-r--r-- 1 root root 4096 Feb  8 10:42 disable
70	-r--r--r-- 1 root root 4096 Feb  8 10:42 latency
71	-r--r--r-- 1 root root 4096 Feb  8 10:42 name
72	-r--r--r-- 1 root root 4096 Feb  8 10:42 power
73	-r--r--r-- 1 root root 4096 Feb  8 10:42 time
74	-r--r--r-- 1 root root 4096 Feb  8 10:42 usage
75	--------------------------------------------------------------------------------
76	
77	
78	* desc : Small description about the idle state (string)
79	* disable : Option to disable this idle state (bool) -> see note below
80	* latency : Latency to exit out of this idle state (in microseconds)
81	* name : Name of the idle state (string)
82	* power : Power consumed while in this idle state (in milliwatts)
83	* time : Total time spent in this idle state (in microseconds)
84	* usage : Number of times this state was entered (count)
85	
86	Note:
87	The behavior and the effect of the disable variable depends on the
88	implementation of a particular governor. In the ladder governor, for
89	example, it is not coherent, i.e. if one is disabling a light state,
90	then all deeper states are disabled as well, but the disable variable
91	does not reflect it. Likewise, if one enables a deep state but a lighter
92	state still is disabled, then this has no effect.
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