1 What: /sys/devices/system/cpu/ 1 What: /sys/devices/system/cpu/
2 Date: pre-git history 2 Date: pre-git history
3 Contact: Linux kernel mailing list <linu 3 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
4 Description: 4 Description:
5 A collection of both global an 5 A collection of both global and individual CPU attributes
6 6
7 Individual CPU attributes are 7 Individual CPU attributes are contained in subdirectories
8 named by the kernel's logical 8 named by the kernel's logical CPU number, e.g.:
9 9
10 /sys/devices/system/cpu/cpuX/ !! 10 /sys/devices/system/cpu/cpu#/
11 11
12 What: /sys/devices/system/cpu/kernel 12 What: /sys/devices/system/cpu/kernel_max
13 /sys/devices/system/cpu/offlin 13 /sys/devices/system/cpu/offline
14 /sys/devices/system/cpu/online 14 /sys/devices/system/cpu/online
15 /sys/devices/system/cpu/possib 15 /sys/devices/system/cpu/possible
16 /sys/devices/system/cpu/presen 16 /sys/devices/system/cpu/present
17 Date: December 2008 17 Date: December 2008
18 Contact: Linux kernel mailing list <linu 18 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
19 Description: CPU topology files that descri 19 Description: CPU topology files that describe kernel limits related to
20 hotplug. Briefly: 20 hotplug. Briefly:
21 21
22 kernel_max: the maximum cpu in 22 kernel_max: the maximum cpu index allowed by the kernel
23 configuration. 23 configuration.
24 24
25 offline: cpus that are not onl 25 offline: cpus that are not online because they have been
26 HOTPLUGGED off or exceed the l 26 HOTPLUGGED off or exceed the limit of cpus allowed by the
27 kernel configuration (kernel_m 27 kernel configuration (kernel_max above).
28 28
29 online: cpus that are online a 29 online: cpus that are online and being scheduled.
30 30
31 possible: cpus that have been 31 possible: cpus that have been allocated resources and can be
32 brought online if they are pre 32 brought online if they are present.
33 33
34 present: cpus that have been i 34 present: cpus that have been identified as being present in
35 the system. 35 the system.
36 36
37 See Documentation/admin-guide/ !! 37 See Documentation/cputopology.txt for more information.
38 38
39 39
40 What: /sys/devices/system/cpu/probe 40 What: /sys/devices/system/cpu/probe
41 /sys/devices/system/cpu/releas 41 /sys/devices/system/cpu/release
42 Date: November 2009 42 Date: November 2009
43 Contact: Linux kernel mailing list <linu 43 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
44 Description: Dynamic addition and removal o 44 Description: Dynamic addition and removal of CPU's. This is not hotplug
45 removal, this is meant complet 45 removal, this is meant complete removal/addition of the CPU
46 from the system. 46 from the system.
47 47
48 probe: writes to this file wil 48 probe: writes to this file will dynamically add a CPU to the
49 system. Information written t 49 system. Information written to the file to add CPU's is
50 architecture specific. 50 architecture specific.
51 51
52 release: writes to this file d 52 release: writes to this file dynamically remove a CPU from
53 the system. Information writt !! 53 the system. Information writtento the file to remove CPU's
54 is architecture specific. 54 is architecture specific.
55 55
56 What: /sys/devices/system/cpu/cpuX/n !! 56 What: /sys/devices/system/cpu/cpu#/node
57 Date: October 2009 57 Date: October 2009
58 Contact: Linux memory management mailin< 58 Contact: Linux memory management mailing list <linux-mm@kvack.org>
59 Description: Discover NUMA node a CPU belon 59 Description: Discover NUMA node a CPU belongs to
60 60
61 When CONFIG_NUMA is enabled, a 61 When CONFIG_NUMA is enabled, a symbolic link that points
62 to the corresponding NUMA node 62 to the corresponding NUMA node directory.
63 63
64 For example, the following sym 64 For example, the following symlink is created for cpu42
65 in NUMA node 2: 65 in NUMA node 2:
66 66
67 /sys/devices/system/cpu/cpu42/ 67 /sys/devices/system/cpu/cpu42/node2 -> ../../node/node2
68 68
69 69
70 What: /sys/devices/system/cpu/cpuX/t !! 70 What: /sys/devices/system/cpu/cpu#/topology/core_id
71 /sys/devices/system/cpu/cpuX/t !! 71 /sys/devices/system/cpu/cpu#/topology/core_siblings
72 /sys/devices/system/cpu/cpuX/t !! 72 /sys/devices/system/cpu/cpu#/topology/core_siblings_list
73 /sys/devices/system/cpu/cpuX/t !! 73 /sys/devices/system/cpu/cpu#/topology/physical_package_id
74 /sys/devices/system/cpu/cpuX/t !! 74 /sys/devices/system/cpu/cpu#/topology/thread_siblings
75 /sys/devices/system/cpu/cpuX/t !! 75 /sys/devices/system/cpu/cpu#/topology/thread_siblings_list
76 Date: December 2008 76 Date: December 2008
77 Contact: Linux kernel mailing list <linu 77 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
78 Description: CPU topology files that descri 78 Description: CPU topology files that describe a logical CPU's relationship
79 to other cores and threads in 79 to other cores and threads in the same physical package.
80 80
81 One cpuX directory is created !! 81 One cpu# directory is created per logical CPU in the system,
82 e.g. /sys/devices/system/cpu/c 82 e.g. /sys/devices/system/cpu/cpu42/.
83 83
84 Briefly, the files above are: 84 Briefly, the files above are:
85 85
86 core_siblings: internal kernel !! 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
87 within the same physical_packa 91 within the same physical_package_id.
88 92
89 core_siblings_list: human-read 93 core_siblings_list: human-readable list of the logical CPU
90 numbers within the same physic !! 94 numbers within the same physical_package_id as cpu#.
91 95
92 physical_package_id: physical !! 96 physical_package_id: physical package id of cpu#. Typically
93 corresponds to a physical sock 97 corresponds to a physical socket number, but the actual value
94 is architecture and platform d 98 is architecture and platform dependent.
95 99
96 thread_siblings: internal kern !! 100 thread_siblings: internel kernel map of cpu#'s hardware
97 threads within the same core a !! 101 threads within the same core as cpu#
98 <<
99 thread_siblings_list: human-re <<
100 threads within the same core a <<
101 102
102 ppin: human-readable Protected !! 103 thread_siblings_list: human-readable list of cpu#'s hardware
103 Number of the socket the cpu# !! 104 threads within the same core as cpu#
104 one per physical_package_id. F <<
105 admin. <<
106 105
107 See Documentation/admin-guide/ !! 106 See Documentation/cputopology.txt for more information.
108 107
109 108
110 What: /sys/devices/system/cpu/cpuidl !! 109 What: /sys/devices/system/cpu/cpuidle/current_driver
111 /sys/devices/system/cpu/cpuidl <<
112 /sys/devices/system/cpu/cpuidl <<
113 /sys/devices/system/cpu/cpuidl 110 /sys/devices/system/cpu/cpuidle/current_governer_ro
114 Date: September 2007 111 Date: September 2007
115 Contact: Linux kernel mailing list <linu 112 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
116 Description: Discover cpuidle policy and me 113 Description: Discover cpuidle policy and mechanism
117 114
118 Various CPUs today support mul 115 Various CPUs today support multiple idle levels that are
119 differentiated by varying exit 116 differentiated by varying exit latencies and power
120 consumption during idle. 117 consumption during idle.
121 118
122 Idle policy (governor) is diff 119 Idle policy (governor) is differentiated from idle mechanism
123 (driver). !! 120 (driver)
124 <<
125 available_governors: (RO) disp <<
126 available governors. <<
127 <<
128 current_driver: (RO) displays <<
129 121
130 current_governor: (RW) display !! 122 current_driver: displays current idle mechanism
131 switch the governor at runtime <<
132 123
133 current_governor_ro: (RO) disp !! 124 current_governor_ro: displays current idle policy
134 125
135 See Documentation/admin-guide/ !! 126 See files in Documentation/cpuidle/ for more information.
136 Documentation/driver-api/pm/cp <<
137 127
138 128
139 What: /sys/devices/system/cpu/cpuX/c !! 129 What: /sys/devices/system/cpu/cpu#/cpufreq/*
140 /sys/devices/system/cpu/cpuX/c <<
141 /sys/devices/system/cpu/cpuX/c <<
142 /sys/devices/system/cpu/cpuX/c <<
143 /sys/devices/system/cpu/cpuX/c <<
144 /sys/devices/system/cpu/cpuX/c <<
145 /sys/devices/system/cpu/cpuX/c <<
146 Date: September 2007 <<
147 KernelVersion: v2.6.24 <<
148 Contact: Linux power management list <li <<
149 Description: <<
150 The directory /sys/devices/sys <<
151 logical CPU specific cpuidle i <<
152 The processor idle states whic <<
153 following attributes: <<
154 <<
155 ======== ==== ================ <<
156 name: (RO) Name of the idle <<
157 <<
158 latency: (RO) The latency to e <<
159 microseconds). <<
160 <<
161 power: (RO) The power consum <<
162 milliwatts). <<
163 <<
164 time: (RO) The total time s <<
165 (in microseconds <<
166 <<
167 usage: (RO) Number of times <<
168 <<
169 above: (RO) Number of times <<
170 observed CPU idl <<
171 (a count). <<
172 <<
173 below: (RO) Number of times <<
174 observed CPU idl <<
175 (a count). <<
176 ======== ==== ================ <<
177 <<
178 What: /sys/devices/system/cpu/cpuX/c <<
179 Date: February 2008 <<
180 KernelVersion: v2.6.25 <<
181 Contact: Linux power management list <li <<
182 Description: <<
183 (RO) A small description about <<
184 <<
185 <<
186 What: /sys/devices/system/cpu/cpuX/c <<
187 Date: March 2012 <<
188 KernelVersion: v3.10 <<
189 Contact: Linux power management list <li <<
190 Description: <<
191 (RW) Option to disable this id <<
192 the effect of the disable vari <<
193 of a particular governor. In t <<
194 it is not coherent, i.e. if on <<
195 all deeper states are disabled <<
196 does not reflect it. Likewise, <<
197 lighter state still is disable <<
198 <<
199 What: /sys/devices/system/cpu/cpuX/c <<
200 Date: December 2019 <<
201 KernelVersion: v5.6 <<
202 Contact: Linux power management list <li <<
203 Description: <<
204 (RO) The default status of thi <<
205 <<
206 What: /sys/devices/system/cpu/cpuX/c <<
207 Date: March 2014 <<
208 KernelVersion: v3.15 <<
209 Contact: Linux power management list <li <<
210 Description: <<
211 (RO) Display the target reside <<
212 time (in microseconds) this cp <<
213 to make the transition worth t <<
214 <<
215 What: /sys/devices/system/cpu/cpuX/c <<
216 Date: March 2018 <<
217 KernelVersion: v4.17 <<
218 Contact: Linux power management list <li <<
219 Description: <<
220 Idle state usage statistics re <<
221 <<
222 This attribute group is only p <<
223 used in suspend-to-idle with s <<
224 <<
225 What: /sys/devices/system/cpu/cpuX/c <<
226 Date: March 2018 <<
227 KernelVersion: v4.17 <<
228 Contact: Linux power management list <li <<
229 Description: <<
230 Total time spent by the CPU in <<
231 tick suspended) after requesti <<
232 <<
233 What: /sys/devices/system/cpu/cpuX/c <<
234 Date: March 2018 <<
235 KernelVersion: v4.17 <<
236 Contact: Linux power management list <li <<
237 Description: <<
238 Total number of times this sta <<
239 while entering suspend-to-idle <<
240 <<
241 What: /sys/devices/system/cpu/cpuX/c <<
242 Date: pre-git history 130 Date: pre-git history
243 Contact: linux-pm@vger.kernel.org 131 Contact: linux-pm@vger.kernel.org
244 Description: Discover and change clock spee 132 Description: Discover and change clock speed of CPUs
245 133
246 Clock scaling allows you to ch 134 Clock scaling allows you to change the clock speed of the
247 CPUs on the fly. This is a nic 135 CPUs on the fly. This is a nice method to save battery
248 power, because the lower the c 136 power, because the lower the clock speed, the less power
249 the CPU consumes. 137 the CPU consumes.
250 138
251 There are many knobs to tweak 139 There are many knobs to tweak in this directory.
252 140
253 See files in Documentation/cpu 141 See files in Documentation/cpu-freq/ for more information.
254 142
>> 143 In particular, read Documentation/cpu-freq/user-guide.txt
>> 144 to learn how to control the knobs.
>> 145
255 146
256 What: /sys/devices/system/cpu/cpuX/c !! 147 What: /sys/devices/system/cpu/cpu#/cpufreq/freqdomain_cpus
257 Date: June 2013 148 Date: June 2013
258 Contact: linux-pm@vger.kernel.org 149 Contact: linux-pm@vger.kernel.org
259 Description: Discover CPUs in the same CPU 150 Description: Discover CPUs in the same CPU frequency coordination domain
260 151
261 freqdomain_cpus is the list of 152 freqdomain_cpus is the list of CPUs (online+offline) that share
262 the same clock/freq domain (po 153 the same clock/freq domain (possibly at the hardware level).
263 That information may be hidden 154 That information may be hidden from the cpufreq core and the
264 value of related_cpus may be d 155 value of related_cpus may be different from freqdomain_cpus. This
265 attribute is useful for user s 156 attribute is useful for user space DVFS controllers to get better
266 power/performance results for 157 power/performance results for platforms using acpi-cpufreq.
267 158
268 This file is only present if t !! 159 This file is only present if the acpi-cpufreq driver is in use.
269 drivers are in use. <<
270 160
271 161
272 What: /sys/devices/system/cpu/cpu*/c 162 What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1}
273 Date: August 2008 163 Date: August 2008
274 KernelVersion: 2.6.27 164 KernelVersion: 2.6.27
275 Contact: Linux kernel mailing list <linu 165 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
276 Description: Disable L3 cache indices 166 Description: Disable L3 cache indices
277 167
278 These files exist in every CPU 168 These files exist in every CPU's cache/index3 directory. Each
279 cache_disable_{0,1} file corre 169 cache_disable_{0,1} file corresponds to one disable slot which
280 can be used to disable a cache 170 can be used to disable a cache index. Reading from these files
281 on a processor with this funct 171 on a processor with this functionality will return the currently
282 disabled index for that node. 172 disabled index for that node. There is one L3 structure per
283 node, or per internal node on 173 node, or per internal node on MCM machines. Writing a valid
284 index to one of these files wi !! 174 index to one of these files will cause the specificed cache
285 index to be disabled. 175 index to be disabled.
286 176
287 All AMD processors with L3 cac 177 All AMD processors with L3 caches provide this functionality.
288 For details, see BKDGs at 178 For details, see BKDGs at
289 https://www.amd.com/en/support !! 179 http://developer.amd.com/documentation/guides/Pages/default.aspx
290 180
291 181
292 What: /sys/devices/system/cpu/cpufre 182 What: /sys/devices/system/cpu/cpufreq/boost
293 Date: August 2012 183 Date: August 2012
294 Contact: Linux kernel mailing list <linu 184 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
295 Description: Processor frequency boosting c 185 Description: Processor frequency boosting control
296 186
297 This switch controls the boost 187 This switch controls the boost setting for the whole system.
298 Boosting allows the CPU and th 188 Boosting allows the CPU and the firmware to run at a frequency
299 beyond its nominal limit. !! 189 beyound it's nominal limit.
>> 190 More details can be found in Documentation/cpu-freq/boost.txt
300 191
301 More details can be found in <<
302 Documentation/admin-guide/pm/c <<
303 192
304 !! 193 What: /sys/devices/system/cpu/cpu#/crash_notes
305 What: /sys/devices/system/cpu/cpuX/c !! 194 /sys/devices/system/cpu/cpu#/crash_notes_size
306 /sys/devices/system/cpu/cpuX/c <<
307 Date: April 2013 195 Date: April 2013
308 Contact: kexec@lists.infradead.org 196 Contact: kexec@lists.infradead.org
309 Description: address and size of the percpu 197 Description: address and size of the percpu note.
310 198
311 crash_notes: the physical addr 199 crash_notes: the physical address of the memory that holds the
312 note of cpuX. !! 200 note of cpu#.
313 201
314 crash_notes_size: size of the !! 202 crash_notes_size: size of the note of cpu#.
315 203
316 204
317 What: /sys/devices/system/cpu/intel_ 205 What: /sys/devices/system/cpu/intel_pstate/max_perf_pct
318 /sys/devices/system/cpu/intel_ 206 /sys/devices/system/cpu/intel_pstate/min_perf_pct
319 /sys/devices/system/cpu/intel_ 207 /sys/devices/system/cpu/intel_pstate/no_turbo
320 Date: February 2013 208 Date: February 2013
321 Contact: linux-pm@vger.kernel.org 209 Contact: linux-pm@vger.kernel.org
322 Description: Parameters for the Intel P-sta 210 Description: Parameters for the Intel P-state driver
323 211
324 Logic for selecting the curren 212 Logic for selecting the current P-state in Intel
325 Sandybridge+ processors. The t 213 Sandybridge+ processors. The three knobs control
326 limits for the P-state that wi 214 limits for the P-state that will be requested by the
327 driver. 215 driver.
328 216
329 max_perf_pct: limits the maxim 217 max_perf_pct: limits the maximum P state that will be requested by
330 the driver stated as a percent 218 the driver stated as a percentage of the available performance.
331 219
332 min_perf_pct: limits the minim 220 min_perf_pct: limits the minimum P state that will be requested by
333 the driver stated as a percent 221 the driver stated as a percentage of the available performance.
334 222
335 no_turbo: limits the driver to 223 no_turbo: limits the driver to selecting P states below the turbo
336 frequency range. 224 frequency range.
337 225
338 More details can be found in !! 226 More details can be found in Documentation/cpu-freq/intel-pstate.txt
339 Documentation/admin-guide/pm/i <<
340 227
341 What: /sys/devices/system/cpu/cpu*/c 228 What: /sys/devices/system/cpu/cpu*/cache/index*/<set_of_attributes_mentioned_below>
342 Date: July 2014(documented, existed 229 Date: July 2014(documented, existed before August 2008)
343 Contact: Sudeep Holla <sudeep.holla@arm. 230 Contact: Sudeep Holla <sudeep.holla@arm.com>
344 Linux kernel mailing list <linu 231 Linux kernel mailing list <linux-kernel@vger.kernel.org>
345 Description: Parameters for the CPU cache a 232 Description: Parameters for the CPU cache attributes
346 233
347 allocation_policy: 234 allocation_policy:
348 - WriteAllocate: !! 235 - WriteAllocate: allocate a memory location to a cache line
349 alloca !! 236 on a cache miss because of a write
350 on a c !! 237 - ReadAllocate: allocate a memory location to a cache line
351 - ReadAllocate: <<
352 alloca <<
353 on a c 238 on a cache miss because of a read
354 - ReadWriteAllocate: !! 239 - ReadWriteAllocate: both writeallocate and readallocate
355 both w !! 240
>> 241 attributes: LEGACY used only on IA64 and is same as write_policy
356 242
357 coherency_line_size: !! 243 coherency_line_size: the minimum amount of data in bytes that gets
358 the minim <<
359 transferr 244 transferred from memory to cache
360 245
361 level: !! 246 level: the cache hierarchy in the multi-level cache configuration
362 the cache hierarchy in <<
363 247
364 number_of_sets: !! 248 number_of_sets: total number of sets in the cache, a set is a
365 total number o <<
366 collection of 249 collection of cache lines with the same cache index
367 250
368 physical_line_partition: !! 251 physical_line_partition: number of physical cache line per cache tag
369 number of phys <<
370 252
371 shared_cpu_list: !! 253 shared_cpu_list: the list of logical cpus sharing the cache
372 the list of lo <<
373 254
374 shared_cpu_map: !! 255 shared_cpu_map: logical cpu mask containing the list of cpus sharing
375 logical cpu ma <<
376 the cache 256 the cache
377 257
378 size: !! 258 size: the total cache size in kB
379 the total cache size i <<
380 259
381 type: 260 type:
382 - Instruction: cache t 261 - Instruction: cache that only holds instructions
383 - Data: cache that onl 262 - Data: cache that only caches data
384 - Unified: cache that 263 - Unified: cache that holds both data and instructions
385 264
386 ways_of_associativity: !! 265 ways_of_associativity: degree of freedom in placing a particular block
387 degree of freedom in p !! 266 of memory in the cache
388 of memory in the cache <<
389 267
390 write_policy: 268 write_policy:
391 - WriteThrough: !! 269 - WriteThrough: data is written to both the cache line
392 data i <<
393 and to 270 and to the block in the lower-level memory
394 - WriteBack: !! 271 - WriteBack: data is written only to the cache line and
395 data is w <<
396 the modif 272 the modified cache line is written to main
397 memory on 273 memory only when it is replaced
398 274
399 275
400 What: /sys/devices/system/cpu/cpu*/c 276 What: /sys/devices/system/cpu/cpu*/cache/index*/id
401 Date: September 2016 277 Date: September 2016
402 Contact: Linux kernel mailing list <linu 278 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
403 Description: Cache id 279 Description: Cache id
404 280
405 The id provides a unique numbe 281 The id provides a unique number for a specific instance of
406 a cache of a particular type. 282 a cache of a particular type. E.g. there may be a level
407 3 unified cache on each socket 283 3 unified cache on each socket in a server and we may
408 assign them ids 0, 1, 2, ... 284 assign them ids 0, 1, 2, ...
409 285
410 Note that id value can be non- 286 Note that id value can be non-contiguous. E.g. level 1
411 caches typically exist per cor 287 caches typically exist per core, but there may not be a
412 power of two cores on a socket 288 power of two cores on a socket, so these caches may be
413 numbered 0, 1, 2, 3, 4, 5, 8, 289 numbered 0, 1, 2, 3, 4, 5, 8, 9, 10, ...
414 290
415 What: /sys/devices/system/cpu/cpuX/c 291 What: /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats
416 /sys/devices/system/cpu/cpuX/c 292 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/turbo_stat
417 /sys/devices/system/cpu/cpuX/c 293 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/sub_turbo_stat
418 /sys/devices/system/cpu/cpuX/c 294 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/unthrottle
419 /sys/devices/system/cpu/cpuX/c 295 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/powercap
420 /sys/devices/system/cpu/cpuX/c 296 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overtemp
421 /sys/devices/system/cpu/cpuX/c 297 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/supply_fault
422 /sys/devices/system/cpu/cpuX/c 298 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overcurrent
423 /sys/devices/system/cpu/cpuX/c 299 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/occ_reset
424 Date: March 2016 300 Date: March 2016
425 Contact: Linux kernel mailing list <linu 301 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
426 Linux for PowerPC mailing list< !! 302 Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
427 Description: POWERNV CPUFreq driver's frequ 303 Description: POWERNV CPUFreq driver's frequency throttle stats directory and
428 attributes 304 attributes
429 305
430 'cpuX/cpufreq/throttle_stats' 306 'cpuX/cpufreq/throttle_stats' directory contains the CPU frequency
431 throttle stat attributes for t 307 throttle stat attributes for the chip. The throttle stats of a cpu
432 is common across all the cpus 308 is common across all the cpus belonging to a chip. Below are the
433 throttle attributes exported i 309 throttle attributes exported in the 'throttle_stats' directory:
434 310
435 - turbo_stat : This file gives 311 - turbo_stat : This file gives the total number of times the max
436 frequency is throttled to lo !! 312 frequency is throttled to lower frequency in turbo (at and above
437 nominal frequency) range of !! 313 nominal frequency) range of frequencies.
438 314
439 - sub_turbo_stat : This file g 315 - sub_turbo_stat : This file gives the total number of times the
440 max frequency is throttled t !! 316 max frequency is throttled to lower frequency in sub-turbo(below
441 nominal frequency) range of !! 317 nominal frequency) range of frequencies.
442 318
443 - unthrottle : This file gives 319 - unthrottle : This file gives the total number of times the max
444 frequency is unthrottled aft !! 320 frequency is unthrottled after being throttled.
445 321
446 - powercap : This file gives t 322 - powercap : This file gives the total number of times the max
447 frequency is throttled due t !! 323 frequency is throttled due to 'Power Capping'.
448 324
449 - overtemp : This file gives t 325 - overtemp : This file gives the total number of times the max
450 frequency is throttled due t !! 326 frequency is throttled due to 'CPU Over Temperature'.
451 327
452 - supply_fault : This file giv 328 - supply_fault : This file gives the total number of times the
453 max frequency is throttled d !! 329 max frequency is throttled due to 'Power Supply Failure'.
454 330
455 - overcurrent : This file give 331 - overcurrent : This file gives the total number of times the
456 max frequency is throttled d !! 332 max frequency is throttled due to 'Overcurrent'.
457 333
458 - occ_reset : This file gives 334 - occ_reset : This file gives the total number of times the max
459 frequency is throttled due t !! 335 frequency is throttled due to 'OCC Reset'.
460 336
461 The sysfs attributes represent 337 The sysfs attributes representing different throttle reasons like
462 powercap, overtemp, supply_fau 338 powercap, overtemp, supply_fault, overcurrent and occ_reset map to
463 the reasons provided by OCC fi 339 the reasons provided by OCC firmware for throttling the frequency.
464 340
465 What: /sys/devices/system/cpu/cpufre 341 What: /sys/devices/system/cpu/cpufreq/policyX/throttle_stats
466 /sys/devices/system/cpu/cpufre 342 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/turbo_stat
467 /sys/devices/system/cpu/cpufre 343 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/sub_turbo_stat
468 /sys/devices/system/cpu/cpufre 344 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/unthrottle
469 /sys/devices/system/cpu/cpufre 345 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/powercap
470 /sys/devices/system/cpu/cpufre 346 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/overtemp
471 /sys/devices/system/cpu/cpufre 347 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/supply_fault
472 /sys/devices/system/cpu/cpufre 348 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/overcurrent
473 /sys/devices/system/cpu/cpufre 349 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/occ_reset
474 Date: March 2016 350 Date: March 2016
475 Contact: Linux kernel mailing list <linu 351 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
476 Linux for PowerPC mailing list< !! 352 Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org>
477 Description: POWERNV CPUFreq driver's frequ 353 Description: POWERNV CPUFreq driver's frequency throttle stats directory and
478 attributes 354 attributes
479 355
480 'policyX/throttle_stats' direc 356 'policyX/throttle_stats' directory and all the attributes are same as
481 the /sys/devices/system/cpu/cp 357 the /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats directory and
482 attributes which give the freq 358 attributes which give the frequency throttle information of the chip.
483 359
484 What: /sys/devices/system/cpu/cpuX/r 360 What: /sys/devices/system/cpu/cpuX/regs/
485 /sys/devices/system/cpu/cpuX/r 361 /sys/devices/system/cpu/cpuX/regs/identification/
486 /sys/devices/system/cpu/cpuX/r 362 /sys/devices/system/cpu/cpuX/regs/identification/midr_el1
487 /sys/devices/system/cpu/cpuX/r 363 /sys/devices/system/cpu/cpuX/regs/identification/revidr_el1
488 /sys/devices/system/cpu/cpuX/r <<
489 Date: June 2016 364 Date: June 2016
490 Contact: Linux ARM Kernel Mailing list < 365 Contact: Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org>
491 Description: AArch64 CPU registers 366 Description: AArch64 CPU registers
492 <<
493 'identification' directory exp 367 'identification' directory exposes the CPU ID registers for
494 identifying model and revision !! 368 identifying model and revision of the CPU.
495 369
496 What: /sys/devices/system/cpu/aarch3 !! 370 What: /sys/devices/system/cpu/cpu#/cpu_capacity
497 Date: May 2021 <<
498 Contact: Linux ARM Kernel Mailing list < <<
499 Description: Identifies the subset of CPUs <<
500 AArch32 (32-bit ARM) applicati <<
501 /sys/devices/system/cpu/{offli <<
502 If absent, then all or none of <<
503 applications and execve() will <<
504 <<
505 What: /sys/devices/system/cpu/cpuX/c <<
506 Date: December 2016 371 Date: December 2016
507 Contact: Linux kernel mailing list <linu 372 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
508 Description: information about CPUs heterog 373 Description: information about CPUs heterogeneity.
509 374
510 cpu_capacity: capacity of cpuX !! 375 cpu_capacity: capacity of cpu#.
511 376
512 What: /sys/devices/system/cpu/vulner 377 What: /sys/devices/system/cpu/vulnerabilities
513 /sys/devices/system/cpu/vulner 378 /sys/devices/system/cpu/vulnerabilities/gather_data_sampling
514 /sys/devices/system/cpu/vulner 379 /sys/devices/system/cpu/vulnerabilities/itlb_multihit
515 /sys/devices/system/cpu/vulner 380 /sys/devices/system/cpu/vulnerabilities/l1tf
516 /sys/devices/system/cpu/vulner 381 /sys/devices/system/cpu/vulnerabilities/mds
517 /sys/devices/system/cpu/vulner 382 /sys/devices/system/cpu/vulnerabilities/meltdown
518 /sys/devices/system/cpu/vulner 383 /sys/devices/system/cpu/vulnerabilities/mmio_stale_data
519 /sys/devices/system/cpu/vulner <<
520 /sys/devices/system/cpu/vulner <<
521 /sys/devices/system/cpu/vulner 384 /sys/devices/system/cpu/vulnerabilities/spec_store_bypass
522 /sys/devices/system/cpu/vulner 385 /sys/devices/system/cpu/vulnerabilities/spectre_v1
523 /sys/devices/system/cpu/vulner 386 /sys/devices/system/cpu/vulnerabilities/spectre_v2
524 /sys/devices/system/cpu/vulner 387 /sys/devices/system/cpu/vulnerabilities/srbds
525 /sys/devices/system/cpu/vulner 388 /sys/devices/system/cpu/vulnerabilities/tsx_async_abort
526 Date: January 2018 389 Date: January 2018
527 Contact: Linux kernel mailing list <linu 390 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
528 Description: Information about CPU vulnerab 391 Description: Information about CPU vulnerabilities
529 392
530 The files are named after the 393 The files are named after the code names of CPU
531 vulnerabilities. The output of 394 vulnerabilities. The output of those files reflects the
532 state of the CPUs in the syste 395 state of the CPUs in the system. Possible output values:
533 396
534 ================ ============ <<
535 "Not affected" CPU is not a 397 "Not affected" CPU is not affected by the vulnerability
536 "Vulnerable" CPU is affec 398 "Vulnerable" CPU is affected and no mitigation in effect
537 "Mitigation: $M" CPU is affec 399 "Mitigation: $M" CPU is affected and mitigation $M is in effect
538 ================ ============ <<
539 400
540 See also: Documentation/admin- 401 See also: Documentation/admin-guide/hw-vuln/index.rst
541 402
542 What: /sys/devices/system/cpu/smt 403 What: /sys/devices/system/cpu/smt
543 /sys/devices/system/cpu/smt/ac 404 /sys/devices/system/cpu/smt/active
544 /sys/devices/system/cpu/smt/co 405 /sys/devices/system/cpu/smt/control
545 Date: June 2018 406 Date: June 2018
546 Contact: Linux kernel mailing list <linu 407 Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org>
547 Description: Control Symmetric Multi Thread !! 408 Description: Control Symetric Multi Threading (SMT)
548 409
549 active: Tells whether SMT is 410 active: Tells whether SMT is active (enabled and siblings online)
550 411
551 control: Read/write interface 412 control: Read/write interface to control SMT. Possible
552 values: 413 values:
553 414
554 ================ ==== !! 415 "on" SMT is enabled
555 "on" SMT !! 416 "off" SMT is disabled
556 "off" SMT !! 417 "forceoff" SMT is force disabled. Cannot be changed.
557 "<N>" SMT !! 418 "notsupported" SMT is not supported by the CPU
558 "forceoff" SMT <<
559 "notsupported" SMT <<
560 "notimplemented" SMT <<
561 impl <<
562 ================ ==== <<
563 419
564 If control status is 420 If control status is "forceoff" or "notsupported" writes
565 are rejected. Note th !! 421 are rejected.
566 offline cores. <<
567 <<
568 What: /sys/devices/system/cpu/cpuX/p <<
569 Date: March 2019 <<
570 Contact: linux-pm@vger.kernel.org <<
571 Description: Intel Energy and Performance B <<
572 <<
573 EPB for the given CPU in a sli <<
574 of 0 corresponds to a hint pre <<
575 and a value of 15 corresponds <<
576 <<
577 In order to change the EPB val <<
578 a number in the 0 - 15 sliding <<
579 strings: "performance", "balan <<
580 "balance-power", "power" (that <<
581 their meaning), to this attrib <<
582 <<
583 This attribute is present for <<
584 Intel EPB feature. <<
585 <<
586 What: /sys/devices/system/cpu/umwait <<
587 /sys/devices/system/cpu/umwait <<
588 /sys/devices/system/cpu/umwait <<
589 Date: May 2019 <<
590 Contact: Linux kernel mailing list <linu <<
591 Description: Umwait control <<
592 <<
593 enable_c02: Read/write interfa <<
594 Read returns C0.2 stat <<
595 0: C0.2 is dis <<
596 1: C0.2 is ena <<
597 <<
598 Write 'y' or '1' or ' <<
599 Write 'n' or '0' or ' <<
600 <<
601 The interface is case <<
602 <<
603 max_time: Read/write interface <<
604 in TSC-quanta that t <<
605 or C0.2 state. The t <<
606 Note that a value of <<
607 Low order two bits m <<
608 <<
609 What: /sys/devices/system/cpu/sev <<
610 /sys/devices/system/cpu/sev/vm <<
611 Date: May 2024 <<
612 Contact: Linux kernel mailing list <linu <<
613 Description: Secure Encrypted Virtualizatio <<
614 <<
615 This directory is only present <<
616 <<
617 vmpl: Reports the Virtual Mach <<
618 the SEV-SNP guest is run <<
619 <<
620 <<
621 What: /sys/devices/system/cpu/svm <<
622 Date: August 2019 <<
623 Contact: Linux kernel mailing list <linu <<
624 Linux for PowerPC mailing list< <<
625 Description: Secure Virtual Machine <<
626 <<
627 If 1, it means the system is u <<
628 Facility in POWER9 and newer p <<
629 Virtual Machine. <<
630 <<
631 What: /sys/devices/system/cpu/cpuX/p <<
632 Date: Apr 2005 <<
633 Contact: Linux for PowerPC mailing list< <<
634 Description: PURR ticks for this CPU since <<
635 <<
636 The Processor Utilization Reso <<
637 a 64-bit counter which provide <<
638 resources used by the CPU thre <<
639 register increases monotonical <<
640 exposes the number of PURR tic <<
641 <<
642 What: /sys/devices/system/cpu/cpuX/s <<
643 Date: Dec 2006 <<
644 Contact: Linux for PowerPC mailing list< <<
645 Description: SPURR ticks for this CPU since <<
646 <<
647 The Scaled Processor Utilizati <<
648 (SPURR) is a 64-bit counter th <<
649 invariant estimate of the reso <<
650 thread. The contents of this r <<
651 monotonically. This sysfs inte <<
652 of SPURR ticks for cpuX. <<
653 <<
654 What: /sys/devices/system/cpu/cpuX/i <<
655 Date: Apr 2020 <<
656 Contact: Linux for PowerPC mailing list< <<
657 Description: PURR ticks for cpuX when it wa <<
658 <<
659 This sysfs interface exposes t <<
660 for cpuX when it was idle. <<
661 <<
662 What: /sys/devices/system/cpu/cpuX/i <<
663 Date: Apr 2020 <<
664 Contact: Linux for PowerPC mailing list< <<
665 Description: SPURR ticks for cpuX when it w <<
666 <<
667 This sysfs interface exposes t <<
668 for cpuX when it was idle. <<
669 <<
670 What: /sys/devices/system/cpu/cpuX/m <<
671 Date: July 2021 <<
672 Contact: Linux ARM Kernel Mailing list < <<
673 Description: Preferred MTE tag checking mod <<
674 <<
675 When a user program specifies <<
676 mode, this sysfs node is used <<
677 be preferred when scheduling a <<
678 values: <<
679 <<
680 ================ ============ <<
681 "sync" Prefer synch <<
682 "asymm" Prefer asymm <<
683 "async" Prefer async <<
684 ================ ============ <<
685 <<
686 See also: Documentation/arch/a <<
687 <<
688 What: /sys/devices/system/cpu/nohz_f <<
689 Date: Apr 2015 <<
690 Contact: Linux kernel mailing list <linu <<
691 Description: <<
692 (RO) the list of CPUs that are <<
693 These CPUs are set by boot par <<
694 <<
695 What: /sys/devices/system/cpu/isolat <<
696 Date: Apr 2015 <<
697 Contact: Linux kernel mailing list <linu <<
698 Description: <<
699 (RO) the list of CPUs that are <<
700 participate in load balancing. <<
701 boot parameter "isolcpus=". <<
702 <<
703 What: /sys/devices/system/cpu/crash_ <<
704 Date: Aug 2023 <<
705 Contact: Linux kernel mailing list <linu <<
706 Description: <<
707 (RO) indicates whether or not <<
708 segments on memory hot un/plug <<
709 need to reload kdump kernel. <<
710 <<
711 What: /sys/devices/system/cpu/enable <<
712 Date: Nov 2022 <<
713 Contact: Linux kernel mailing list <linu <<
714 Description: <<
715 (RO) the list of CPUs that can <<
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