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2ceb3fb0 AC |
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 | ||
d93fc863 AC |
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 | ||
12633e80 NF |
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. | |
657348a0 | 55 | |
cba5dd7f AC |
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 | ||
663fb2fc AC |
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 | ||
c1fb5c47 AC |
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 | ||
0cda8b91 AC |
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 | ||
eecaaba5 BP |
147 | What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1} |
148 | Date: August 2008 | |
2fad2d9b | 149 | KernelVersion: 2.6.27 |
eecaaba5 BP |
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 | |
615b7300 AP |
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 |