Commit | Line | Data |
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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 | ||
e6dcfa7c AC |
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 | ||
2ceb3fb0 | 36 | |
d93fc863 AC |
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 | ||
12633e80 NF |
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. | |
657348a0 AC |
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 | ||
cba5dd7f AC |
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 | ||
663fb2fc AC |
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 | ||
c1fb5c47 AC |
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 | ||
0cda8b91 AC |
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 | ||
2fad2d9b ML |
186 | What: /sys/devices/system/cpu/cpu*/cache/index*/cache_disable_X |
187 | Date: August 2008 | |
188 | KernelVersion: 2.6.27 | |
189 | Contact: mark.langsdorf@amd.com | |
190 | Description: These files exist in every cpu's cache index directories. | |
191 | There are currently 2 cache_disable_# files in each | |
192 | directory. Reading from these files on a supported | |
193 | processor will return that cache disable index value | |
194 | for that processor and node. Writing to one of these | |
195 | files will cause the specificed cache index to be disabled. | |
196 | ||
197 | Currently, only AMD Family 10h Processors support cache index | |
198 | disable, and only for their L3 caches. See the BIOS and | |
199 | Kernel Developer's Guide at | |
0ea6e611 | 200 | http://support.amd.com/us/Embedded_TechDocs/31116-Public-GH-BKDG_3-28_5-28-09.pdf |
2fad2d9b ML |
201 | for formatting information and other details on the |
202 | cache index disable. | |
203 | Users: joachim.deguara@amd.com |