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Based on kernel version 3.3. Page generated on 2012-03-23 21:23 EST.

1	What:		/sys/devices/system/cpu/
2	Date:		pre-git history
3	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
4	Description:
5			A collection of both global and individual CPU attributes
6	
7			Individual CPU attributes are contained in subdirectories
8			named by the kernel's logical CPU number, e.g.:
9	
10			/sys/devices/system/cpu/cpu#/
11	
12	What:		/sys/devices/system/cpu/sched_mc_power_savings
13			/sys/devices/system/cpu/sched_smt_power_savings
14	Date:		June 2006
15	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
16	Description:	Discover and adjust the kernel's multi-core scheduler support.
17	
18			Possible values are:
19	
20			0 - No power saving load balance (default value)
21			1 - Fill one thread/core/package first for long running threads
22			2 - Also bias task wakeups to semi-idle cpu package for power
23			    savings
24	
25			sched_mc_power_savings is dependent upon SCHED_MC, which is
26			itself architecture dependent.
27	
28			sched_smt_power_savings is dependent upon SCHED_SMT, which
29			is itself architecture dependent.
30	
31			The two files are independent of each other. It is possible
32			that one file may be present without the other.
33	
34			Introduced by git commit 5c45bf27.
35	
36	
37	What:		/sys/devices/system/cpu/kernel_max
38			/sys/devices/system/cpu/offline
39			/sys/devices/system/cpu/online
40			/sys/devices/system/cpu/possible
41			/sys/devices/system/cpu/present
42	Date:		December 2008
43	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
44	Description:	CPU topology files that describe kernel limits related to
45			hotplug. Briefly:
46	
47			kernel_max: the maximum cpu index allowed by the kernel
48			configuration.
49	
50			offline: cpus that are not online because they have been
51			HOTPLUGGED off or exceed the limit of cpus allowed by the
52			kernel configuration (kernel_max above).
53	
54			online: cpus that are online and being scheduled.
55	
56			possible: cpus that have been allocated resources and can be
57			brought online if they are present.
58	
59			present: cpus that have been identified as being present in
60			the system.
61	
62			See Documentation/cputopology.txt for more information.
63	
64	
65	What:		/sys/devices/system/cpu/probe
66			/sys/devices/system/cpu/release
67	Date:		November 2009
68	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
69	Description:	Dynamic addition and removal of CPU's.  This is not hotplug
70			removal, this is meant complete removal/addition of the CPU
71			from the system.
72	
73			probe: writes to this file will dynamically add a CPU to the
74			system.  Information written to the file to add CPU's is
75			architecture specific.
76	
77			release: writes to this file dynamically remove a CPU from
78			the system.  Information writtento the file to remove CPU's
79			is architecture specific.
80	
81	What:		/sys/devices/system/cpu/cpu#/node
82	Date:		October 2009
83	Contact:	Linux memory management mailing list <linux-mm@kvack.org>
84	Description:	Discover NUMA node a CPU belongs to
85	
86			When CONFIG_NUMA is enabled, a symbolic link that points
87			to the corresponding NUMA node directory.
88	
89			For example, the following symlink is created for cpu42
90			in NUMA node 2:
91	
92			/sys/devices/system/cpu/cpu42/node2 -> ../../node/node2
93	
94	
95	What:		/sys/devices/system/cpu/cpu#/node
96	Date:		October 2009
97	Contact:	Linux memory management mailing list <linux-mm@kvack.org>
98	Description:	Discover NUMA node a CPU belongs to
99	
100			When CONFIG_NUMA is enabled, a symbolic link that points
101			to the corresponding NUMA node directory.
102	
103			For example, the following symlink is created for cpu42
104			in NUMA node 2:
105	
106			/sys/devices/system/cpu/cpu42/node2 -> ../../node/node2
107	
108	
109	What:		/sys/devices/system/cpu/cpu#/topology/core_id
110			/sys/devices/system/cpu/cpu#/topology/core_siblings
111			/sys/devices/system/cpu/cpu#/topology/core_siblings_list
112			/sys/devices/system/cpu/cpu#/topology/physical_package_id
113			/sys/devices/system/cpu/cpu#/topology/thread_siblings
114			/sys/devices/system/cpu/cpu#/topology/thread_siblings_list
115	Date:		December 2008
116	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
117	Description:	CPU topology files that describe a logical CPU's relationship
118			to other cores and threads in the same physical package.
119	
120			One cpu# directory is created per logical CPU in the system,
121			e.g. /sys/devices/system/cpu/cpu42/.
122	
123			Briefly, the files above are:
124	
125			core_id: the CPU core ID of cpu#. Typically it is the
126			hardware platform's identifier (rather than the kernel's).
127			The actual value is architecture and platform dependent.
128	
129			core_siblings: internal kernel map of cpu#'s hardware threads
130			within the same physical_package_id.
131	
132			core_siblings_list: human-readable list of the logical CPU
133			numbers within the same physical_package_id as cpu#.
134	
135			physical_package_id: physical package id of cpu#. Typically
136			corresponds to a physical socket number, but the actual value
137			is architecture and platform dependent.
138	
139			thread_siblings: internel kernel map of cpu#'s hardware
140			threads within the same core as cpu#
141	
142			thread_siblings_list: human-readable list of cpu#'s hardware
143			threads within the same core as cpu#
144	
145			See Documentation/cputopology.txt for more information.
146	
147	
148	What:		/sys/devices/system/cpu/cpuidle/current_driver
149			/sys/devices/system/cpu/cpuidle/current_governer_ro
150	Date:		September 2007
151	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
152	Description:	Discover cpuidle policy and mechanism
153	
154			Various CPUs today support multiple idle levels that are
155			differentiated by varying exit latencies and power
156			consumption during idle.
157	
158			Idle policy (governor) is differentiated from idle mechanism
159			(driver)
160	
161			current_driver: displays current idle mechanism
162	
163			current_governor_ro: displays current idle policy
164	
165			See files in Documentation/cpuidle/ for more information.
166	
167	
168	What:		/sys/devices/system/cpu/cpu#/cpufreq/*
169	Date:		pre-git history
170	Contact:	cpufreq@vger.kernel.org
171	Description:	Discover and change clock speed of CPUs
172	
173			Clock scaling allows you to change the clock speed of the
174			CPUs on the fly. This is a nice method to save battery
175			power, because the lower the clock speed, the less power
176			the CPU consumes.
177	
178			There are many knobs to tweak in this directory.
179	
180			See files in Documentation/cpu-freq/ for more information.
181	
182			In particular, read Documentation/cpu-freq/user-guide.txt
183			to learn how to control the knobs.
184	
185	
186	What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
187	Date:		August 2008
188	KernelVersion:	2.6.27
189	Contact:	discuss@x86-64.org
190	Description:	Disable L3 cache indices
191	
192			These files exist in every CPU's cache/index3 directory. Each
193			cache_disable_{0,1} file corresponds to one disable slot which
194			can be used to disable a cache index. Reading from these files
195			on a processor with this functionality will return the currently
196			disabled index for that node. There is one L3 structure per
197			node, or per internal node on MCM machines. Writing a valid
198			index to one of these files will cause the specificed cache
199			index to be disabled.
200	
201			All AMD processors with L3 caches provide this functionality.
202			For details, see BKDGs at
203			http://developer.amd.com/documentation/guides/Pages/default.aspx
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