1 What: /sys/devices/system/cpu/
2 Date: pre-git history
3 Contact: Linux kernel mailing list <linu
4 Description:
5 A collection of both global an
6
7 Individual CPU attributes are
8 named by the kernel's logical
9
10 /sys/devices/system/cpu/cpuX/
11
12 What: /sys/devices/system/cpu/kernel
13 /sys/devices/system/cpu/offlin
14 /sys/devices/system/cpu/online
15 /sys/devices/system/cpu/possib
16 /sys/devices/system/cpu/presen
17 Date: December 2008
18 Contact: Linux kernel mailing list <linu
19 Description: CPU topology files that descri
20 hotplug. Briefly:
21
22 kernel_max: the maximum cpu in
23 configuration.
24
25 offline: cpus that are not onl
26 HOTPLUGGED off or exceed the l
27 kernel configuration (kernel_m
28
29 online: cpus that are online a
30
31 possible: cpus that have been
32 brought online if they are pre
33
34 present: cpus that have been i
35 the system.
36
37 See Documentation/admin-guide/
38
39
40 What: /sys/devices/system/cpu/probe
41 /sys/devices/system/cpu/releas
42 Date: November 2009
43 Contact: Linux kernel mailing list <linu
44 Description: Dynamic addition and removal o
45 removal, this is meant complet
46 from the system.
47
48 probe: writes to this file wil
49 system. Information written t
50 architecture specific.
51
52 release: writes to this file d
53 the system. Information writt
54 is architecture specific.
55
56 What: /sys/devices/system/cpu/cpuX/n
57 Date: October 2009
58 Contact: Linux memory management mailin<
59 Description: Discover NUMA node a CPU belon
60
61 When CONFIG_NUMA is enabled, a
62 to the corresponding NUMA node
63
64 For example, the following sym
65 in NUMA node 2:
66
67 /sys/devices/system/cpu/cpu42/
68
69
70 What: /sys/devices/system/cpu/cpuX/t
71 /sys/devices/system/cpu/cpuX/t
72 /sys/devices/system/cpu/cpuX/t
73 /sys/devices/system/cpu/cpuX/t
74 /sys/devices/system/cpu/cpuX/t
75 /sys/devices/system/cpu/cpuX/t
76 Date: December 2008
77 Contact: Linux kernel mailing list <linu
78 Description: CPU topology files that descri
79 to other cores and threads in
80
81 One cpuX directory is created
82 e.g. /sys/devices/system/cpu/c
83
84 Briefly, the files above are:
85
86 core_siblings: internal kernel
87 within the same physical_packa
88
89 core_siblings_list: human-read
90 numbers within the same physic
91
92 physical_package_id: physical
93 corresponds to a physical sock
94 is architecture and platform d
95
96 thread_siblings: internal kern
97 threads within the same core a
98
99 thread_siblings_list: human-re
100 threads within the same core a
101
102 ppin: human-readable Protected
103 Number of the socket the cpu#
104 one per physical_package_id. F
105 admin.
106
107 See Documentation/admin-guide/
108
109
110 What: /sys/devices/system/cpu/cpuidl
111 /sys/devices/system/cpu/cpuidl
112 /sys/devices/system/cpu/cpuidl
113 /sys/devices/system/cpu/cpuidl
114 Date: September 2007
115 Contact: Linux kernel mailing list <linu
116 Description: Discover cpuidle policy and me
117
118 Various CPUs today support mul
119 differentiated by varying exit
120 consumption during idle.
121
122 Idle policy (governor) is diff
123 (driver).
124
125 available_governors: (RO) disp
126 available governors.
127
128 current_driver: (RO) displays
129
130 current_governor: (RW) display
131 switch the governor at runtime
132
133 current_governor_ro: (RO) disp
134
135 See Documentation/admin-guide/
136 Documentation/driver-api/pm/cp
137
138
139 What: /sys/devices/system/cpu/cpuX/c
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
243 Contact: linux-pm@vger.kernel.org
244 Description: Discover and change clock spee
245
246 Clock scaling allows you to ch
247 CPUs on the fly. This is a nic
248 power, because the lower the c
249 the CPU consumes.
250
251 There are many knobs to tweak
252
253 See files in Documentation/cpu
254
255
256 What: /sys/devices/system/cpu/cpuX/c
257 Date: June 2013
258 Contact: linux-pm@vger.kernel.org
259 Description: Discover CPUs in the same CPU
260
261 freqdomain_cpus is the list of
262 the same clock/freq domain (po
263 That information may be hidden
264 value of related_cpus may be d
265 attribute is useful for user s
266 power/performance results for
267
268 This file is only present if t
269 drivers are in use.
270
271
272 What: /sys/devices/system/cpu/cpu*/c
273 Date: August 2008
274 KernelVersion: 2.6.27
275 Contact: Linux kernel mailing list <linu
276 Description: Disable L3 cache indices
277
278 These files exist in every CPU
279 cache_disable_{0,1} file corre
280 can be used to disable a cache
281 on a processor with this funct
282 disabled index for that node.
283 node, or per internal node on
284 index to one of these files wi
285 index to be disabled.
286
287 All AMD processors with L3 cac
288 For details, see BKDGs at
289 https://www.amd.com/en/support
290
291
292 What: /sys/devices/system/cpu/cpufre
293 Date: August 2012
294 Contact: Linux kernel mailing list <linu
295 Description: Processor frequency boosting c
296
297 This switch controls the boost
298 Boosting allows the CPU and th
299 beyond its nominal limit.
300
301 More details can be found in
302 Documentation/admin-guide/pm/c
303
304
305 What: /sys/devices/system/cpu/cpuX/c
306 /sys/devices/system/cpu/cpuX/c
307 Date: April 2013
308 Contact: kexec@lists.infradead.org
309 Description: address and size of the percpu
310
311 crash_notes: the physical addr
312 note of cpuX.
313
314 crash_notes_size: size of the
315
316
317 What: /sys/devices/system/cpu/intel_
318 /sys/devices/system/cpu/intel_
319 /sys/devices/system/cpu/intel_
320 Date: February 2013
321 Contact: linux-pm@vger.kernel.org
322 Description: Parameters for the Intel P-sta
323
324 Logic for selecting the curren
325 Sandybridge+ processors. The t
326 limits for the P-state that wi
327 driver.
328
329 max_perf_pct: limits the maxim
330 the driver stated as a percent
331
332 min_perf_pct: limits the minim
333 the driver stated as a percent
334
335 no_turbo: limits the driver to
336 frequency range.
337
338 More details can be found in
339 Documentation/admin-guide/pm/i
340
341 What: /sys/devices/system/cpu/cpu*/c
342 Date: July 2014(documented, existed
343 Contact: Sudeep Holla <sudeep.holla@arm.
344 Linux kernel mailing list <linu
345 Description: Parameters for the CPU cache a
346
347 allocation_policy:
348 - WriteAllocate:
349 alloca
350 on a c
351 - ReadAllocate:
352 alloca
353 on a c
354 - ReadWriteAllocate:
355 both w
356
357 coherency_line_size:
358 the minim
359 transferr
360
361 level:
362 the cache hierarchy in
363
364 number_of_sets:
365 total number o
366 collection of
367
368 physical_line_partition:
369 number of phys
370
371 shared_cpu_list:
372 the list of lo
373
374 shared_cpu_map:
375 logical cpu ma
376 the cache
377
378 size:
379 the total cache size i
380
381 type:
382 - Instruction: cache t
383 - Data: cache that onl
384 - Unified: cache that
385
386 ways_of_associativity:
387 degree of freedom in p
388 of memory in the cache
389
390 write_policy:
391 - WriteThrough:
392 data i
393 and to
394 - WriteBack:
395 data is w
396 the modif
397 memory on
398
399
400 What: /sys/devices/system/cpu/cpu*/c
401 Date: September 2016
402 Contact: Linux kernel mailing list <linu
403 Description: Cache id
404
405 The id provides a unique numbe
406 a cache of a particular type.
407 3 unified cache on each socket
408 assign them ids 0, 1, 2, ...
409
410 Note that id value can be non-
411 caches typically exist per cor
412 power of two cores on a socket
413 numbered 0, 1, 2, 3, 4, 5, 8,
414
415 What: /sys/devices/system/cpu/cpuX/c
416 /sys/devices/system/cpu/cpuX/c
417 /sys/devices/system/cpu/cpuX/c
418 /sys/devices/system/cpu/cpuX/c
419 /sys/devices/system/cpu/cpuX/c
420 /sys/devices/system/cpu/cpuX/c
421 /sys/devices/system/cpu/cpuX/c
422 /sys/devices/system/cpu/cpuX/c
423 /sys/devices/system/cpu/cpuX/c
424 Date: March 2016
425 Contact: Linux kernel mailing list <linu
426 Linux for PowerPC mailing list<
427 Description: POWERNV CPUFreq driver's frequ
428 attributes
429
430 'cpuX/cpufreq/throttle_stats'
431 throttle stat attributes for t
432 is common across all the cpus
433 throttle attributes exported i
434
435 - turbo_stat : This file gives
436 frequency is throttled to lo
437 nominal frequency) range of
438
439 - sub_turbo_stat : This file g
440 max frequency is throttled t
441 nominal frequency) range of
442
443 - unthrottle : This file gives
444 frequency is unthrottled aft
445
446 - powercap : This file gives t
447 frequency is throttled due t
448
449 - overtemp : This file gives t
450 frequency is throttled due t
451
452 - supply_fault : This file giv
453 max frequency is throttled d
454
455 - overcurrent : This file give
456 max frequency is throttled d
457
458 - occ_reset : This file gives
459 frequency is throttled due t
460
461 The sysfs attributes represent
462 powercap, overtemp, supply_fau
463 the reasons provided by OCC fi
464
465 What: /sys/devices/system/cpu/cpufre
466 /sys/devices/system/cpu/cpufre
467 /sys/devices/system/cpu/cpufre
468 /sys/devices/system/cpu/cpufre
469 /sys/devices/system/cpu/cpufre
470 /sys/devices/system/cpu/cpufre
471 /sys/devices/system/cpu/cpufre
472 /sys/devices/system/cpu/cpufre
473 /sys/devices/system/cpu/cpufre
474 Date: March 2016
475 Contact: Linux kernel mailing list <linu
476 Linux for PowerPC mailing list<
477 Description: POWERNV CPUFreq driver's frequ
478 attributes
479
480 'policyX/throttle_stats' direc
481 the /sys/devices/system/cpu/cp
482 attributes which give the freq
483
484 What: /sys/devices/system/cpu/cpuX/r
485 /sys/devices/system/cpu/cpuX/r
486 /sys/devices/system/cpu/cpuX/r
487 /sys/devices/system/cpu/cpuX/r
488 /sys/devices/system/cpu/cpuX/r
489 Date: June 2016
490 Contact: Linux ARM Kernel Mailing list <
491 Description: AArch64 CPU registers
492
493 'identification' directory exp
494 identifying model and revision
495
496 What: /sys/devices/system/cpu/aarch3
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
507 Contact: Linux kernel mailing list <linu
508 Description: information about CPUs heterog
509
510 cpu_capacity: capacity of cpuX
511
512 What: /sys/devices/system/cpu/vulner
513 /sys/devices/system/cpu/vulner
514 /sys/devices/system/cpu/vulner
515 /sys/devices/system/cpu/vulner
516 /sys/devices/system/cpu/vulner
517 /sys/devices/system/cpu/vulner
518 /sys/devices/system/cpu/vulner
519 /sys/devices/system/cpu/vulner
520 /sys/devices/system/cpu/vulner
521 /sys/devices/system/cpu/vulner
522 /sys/devices/system/cpu/vulner
523 /sys/devices/system/cpu/vulner
524 /sys/devices/system/cpu/vulner
525 /sys/devices/system/cpu/vulner
526 Date: January 2018
527 Contact: Linux kernel mailing list <linu
528 Description: Information about CPU vulnerab
529
530 The files are named after the
531 vulnerabilities. The output of
532 state of the CPUs in the syste
533
534 ================ ============
535 "Not affected" CPU is not a
536 "Vulnerable" CPU is affec
537 "Mitigation: $M" CPU is affec
538 ================ ============
539
540 See also: Documentation/admin-
541
542 What: /sys/devices/system/cpu/smt
543 /sys/devices/system/cpu/smt/ac
544 /sys/devices/system/cpu/smt/co
545 Date: June 2018
546 Contact: Linux kernel mailing list <linu
547 Description: Control Symmetric Multi Thread
548
549 active: Tells whether SMT is
550
551 control: Read/write interface
552 values:
553
554 ================ ====
555 "on" SMT
556 "off" SMT
557 "<N>" SMT
558 "forceoff" SMT
559 "notsupported" SMT
560 "notimplemented" SMT
561 impl
562 ================ ====
563
564 If control status is
565 are rejected. Note th
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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