About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / ABI / testing / sysfs-devices-system-cpu




Custom Search

Based on kernel version 3.9. Page generated on 2013-05-02 22:53 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/kernel_max
13			/sys/devices/system/cpu/offline
14			/sys/devices/system/cpu/online
15			/sys/devices/system/cpu/possible
16			/sys/devices/system/cpu/present
17	Date:		December 2008
18	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
19	Description:	CPU topology files that describe kernel limits related to
20			hotplug. Briefly:
21	
22			kernel_max: the maximum cpu index allowed by the kernel
23			configuration.
24	
25			offline: cpus that are not online because they have been
26			HOTPLUGGED off or exceed the limit of cpus allowed by the
27			kernel configuration (kernel_max above).
28	
29			online: cpus that are online and being scheduled.
30	
31			possible: cpus that have been allocated resources and can be
32			brought online if they are present.
33	
34			present: cpus that have been identified as being present in
35			the system.
36	
37			See Documentation/cputopology.txt for more information.
38	
39	
40	What:		/sys/devices/system/cpu/probe
41			/sys/devices/system/cpu/release
42	Date:		November 2009
43	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
44	Description:	Dynamic addition and removal of CPU's.  This is not hotplug
45			removal, this is meant complete removal/addition of the CPU
46			from the system.
47	
48			probe: writes to this file will dynamically add a CPU to the
49			system.  Information written to the file to add CPU's is
50			architecture specific.
51	
52			release: writes to this file dynamically remove a CPU from
53			the system.  Information writtento the file to remove CPU's
54			is architecture specific.
55	
56	What:		/sys/devices/system/cpu/cpu#/node
57	Date:		October 2009
58	Contact:	Linux memory management mailing list <linux-mm@kvack.org>
59	Description:	Discover NUMA node a CPU belongs to
60	
61			When CONFIG_NUMA is enabled, a symbolic link that points
62			to the corresponding NUMA node directory.
63	
64			For example, the following symlink is created for cpu42
65			in NUMA node 2:
66	
67			/sys/devices/system/cpu/cpu42/node2 -> ../../node/node2
68	
69	
70	What:		/sys/devices/system/cpu/cpu#/topology/core_id
71			/sys/devices/system/cpu/cpu#/topology/core_siblings
72			/sys/devices/system/cpu/cpu#/topology/core_siblings_list
73			/sys/devices/system/cpu/cpu#/topology/physical_package_id
74			/sys/devices/system/cpu/cpu#/topology/thread_siblings
75			/sys/devices/system/cpu/cpu#/topology/thread_siblings_list
76	Date:		December 2008
77	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
78	Description:	CPU topology files that describe a logical CPU's relationship
79			to other cores and threads in the same physical package.
80	
81			One cpu# directory is created per logical CPU in the system,
82			e.g. /sys/devices/system/cpu/cpu42/.
83	
84			Briefly, the files above are:
85	
86			core_id: the CPU core ID of cpu#. Typically it is the
87			hardware platform's identifier (rather than the kernel's).
88			The actual value is architecture and platform dependent.
89	
90			core_siblings: internal kernel map of cpu#'s hardware threads
91			within the same physical_package_id.
92	
93			core_siblings_list: human-readable list of the logical CPU
94			numbers within the same physical_package_id as cpu#.
95	
96			physical_package_id: physical package id of cpu#. Typically
97			corresponds to a physical socket number, but the actual value
98			is architecture and platform dependent.
99	
100			thread_siblings: internel kernel map of cpu#'s hardware
101			threads within the same core as cpu#
102	
103			thread_siblings_list: human-readable list of cpu#'s hardware
104			threads within the same core as cpu#
105	
106			See Documentation/cputopology.txt for more information.
107	
108	
109	What:		/sys/devices/system/cpu/cpuidle/current_driver
110			/sys/devices/system/cpu/cpuidle/current_governer_ro
111	Date:		September 2007
112	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
113	Description:	Discover cpuidle policy and mechanism
114	
115			Various CPUs today support multiple idle levels that are
116			differentiated by varying exit latencies and power
117			consumption during idle.
118	
119			Idle policy (governor) is differentiated from idle mechanism
120			(driver)
121	
122			current_driver: displays current idle mechanism
123	
124			current_governor_ro: displays current idle policy
125	
126			See files in Documentation/cpuidle/ for more information.
127	
128	
129	What:		/sys/devices/system/cpu/cpu#/cpufreq/*
130	Date:		pre-git history
131	Contact:	cpufreq@vger.kernel.org
132	Description:	Discover and change clock speed of CPUs
133	
134			Clock scaling allows you to change the clock speed of the
135			CPUs on the fly. This is a nice method to save battery
136			power, because the lower the clock speed, the less power
137			the CPU consumes.
138	
139			There are many knobs to tweak in this directory.
140	
141			See files in Documentation/cpu-freq/ for more information.
142	
143			In particular, read Documentation/cpu-freq/user-guide.txt
144			to learn how to control the knobs.
145	
146	
147	What:		/sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
148	Date:		August 2008
149	KernelVersion:	2.6.27
150	Contact:	discuss@x86-64.org
151	Description:	Disable L3 cache indices
152	
153			These files exist in every CPU's cache/index3 directory. Each
154			cache_disable_{0,1} file corresponds to one disable slot which
155			can be used to disable a cache index. Reading from these files
156			on a processor with this functionality will return the currently
157			disabled index for that node. There is one L3 structure per
158			node, or per internal node on MCM machines. Writing a valid
159			index to one of these files will cause the specificed cache
160			index to be disabled.
161	
162			All AMD processors with L3 caches provide this functionality.
163			For details, see BKDGs at
164			http://developer.amd.com/documentation/guides/Pages/default.aspx
165	
166	
167	What:		/sys/devices/system/cpu/cpufreq/boost
168	Date:		August 2012
169	Contact:	Linux kernel mailing list <linux-kernel@vger.kernel.org>
170	Description:	Processor frequency boosting control
171	
172			This switch controls the boost setting for the whole system.
173			Boosting allows the CPU and the firmware to run at a frequency
174			beyound it's nominal limit.
175			More details can be found in Documentation/cpu-freq/boost.txt
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog
Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.