1What: /sys/devices/system/cpu/ 2Date: pre-git history 3Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 4Description: 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/cpuX/ 11 12What: /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 17Date: December 2008 18Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 19Description: 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/admin-guide/cputopology.rst for more information. 38 39 40What: /sys/devices/system/cpu/probe 41 /sys/devices/system/cpu/release 42Date: November 2009 43Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 44Description: 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 written to the file to remove CPU's 54 is architecture specific. 55 56What: /sys/devices/system/cpu/cpuX/node 57Date: October 2009 58Contact: Linux memory management mailing list <linux-mm@kvack.org> 59Description: 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 70What: /sys/devices/system/cpu/cpuX/topology/core_siblings 71 /sys/devices/system/cpu/cpuX/topology/core_siblings_list 72 /sys/devices/system/cpu/cpuX/topology/physical_package_id 73 /sys/devices/system/cpu/cpuX/topology/thread_siblings 74 /sys/devices/system/cpu/cpuX/topology/thread_siblings_list 75 /sys/devices/system/cpu/cpuX/topology/ppin 76Date: December 2008 77Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 78Description: CPU topology files that describe a logical CPU's relationship 79 to other cores and threads in the same physical package. 80 81 One cpuX 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_siblings: internal kernel map of cpuX's hardware threads 87 within the same physical_package_id. 88 89 core_siblings_list: human-readable list of the logical CPU 90 numbers within the same physical_package_id as cpuX. 91 92 physical_package_id: physical package id of cpuX. Typically 93 corresponds to a physical socket number, but the actual value 94 is architecture and platform dependent. 95 96 thread_siblings: internal kernel map of cpuX's hardware 97 threads within the same core as cpuX 98 99 thread_siblings_list: human-readable list of cpuX's hardware 100 threads within the same core as cpuX 101 102 ppin: human-readable Protected Processor Identification 103 Number of the socket the cpu# belongs to. There should be 104 one per physical_package_id. File is readable only to 105 admin. 106 107 See Documentation/admin-guide/cputopology.rst for more information. 108 109 110What: /sys/devices/system/cpu/cpuidle/available_governors 111 /sys/devices/system/cpu/cpuidle/current_driver 112 /sys/devices/system/cpu/cpuidle/current_governor 113 /sys/devices/system/cpu/cpuidle/current_governer_ro 114Date: September 2007 115Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 116Description: Discover cpuidle policy and mechanism 117 118 Various CPUs today support multiple idle levels that are 119 differentiated by varying exit latencies and power 120 consumption during idle. 121 122 Idle policy (governor) is differentiated from idle mechanism 123 (driver). 124 125 available_governors: (RO) displays a space separated list of 126 available governors. 127 128 current_driver: (RO) displays current idle mechanism. 129 130 current_governor: (RW) displays current idle policy. Users can 131 switch the governor at runtime by writing to this file. 132 133 current_governor_ro: (RO) displays current idle policy. 134 135 See Documentation/admin-guide/pm/cpuidle.rst and 136 Documentation/driver-api/pm/cpuidle.rst for more information. 137 138 139What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/name 140 /sys/devices/system/cpu/cpuX/cpuidle/stateN/latency 141 /sys/devices/system/cpu/cpuX/cpuidle/stateN/power 142 /sys/devices/system/cpu/cpuX/cpuidle/stateN/time 143 /sys/devices/system/cpu/cpuX/cpuidle/stateN/usage 144 /sys/devices/system/cpu/cpuX/cpuidle/stateN/above 145 /sys/devices/system/cpu/cpuX/cpuidle/stateN/below 146Date: September 2007 147KernelVersion: v2.6.24 148Contact: Linux power management list <linux-pm@vger.kernel.org> 149Description: 150 The directory /sys/devices/system/cpu/cpuX/cpuidle contains per 151 logical CPU specific cpuidle information for each online cpu X. 152 The processor idle states which are available for use have the 153 following attributes: 154 155 ======== ==== ================================================= 156 name: (RO) Name of the idle state (string). 157 158 latency: (RO) The latency to exit out of this idle state (in 159 microseconds). 160 161 power: (RO) The power consumed while in this idle state (in 162 milliwatts). 163 164 time: (RO) The total time spent in this idle state 165 (in microseconds). 166 167 usage: (RO) Number of times this state was entered (a count). 168 169 above: (RO) Number of times this state was entered, but the 170 observed CPU idle duration was too short for it 171 (a count). 172 173 below: (RO) Number of times this state was entered, but the 174 observed CPU idle duration was too long for it 175 (a count). 176 ======== ==== ================================================= 177 178What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/desc 179Date: February 2008 180KernelVersion: v2.6.25 181Contact: Linux power management list <linux-pm@vger.kernel.org> 182Description: 183 (RO) A small description about the idle state (string). 184 185 186What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/disable 187Date: March 2012 188KernelVersion: v3.10 189Contact: Linux power management list <linux-pm@vger.kernel.org> 190Description: 191 (RW) Option to disable this idle state (bool). The behavior and 192 the effect of the disable variable depends on the implementation 193 of a particular governor. In the ladder governor, for example, 194 it is not coherent, i.e. if one is disabling a light state, then 195 all deeper states are disabled as well, but the disable variable 196 does not reflect it. Likewise, if one enables a deep state but a 197 lighter state still is disabled, then this has no effect. 198 199What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/default_status 200Date: December 2019 201KernelVersion: v5.6 202Contact: Linux power management list <linux-pm@vger.kernel.org> 203Description: 204 (RO) The default status of this state, "enabled" or "disabled". 205 206What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/residency 207Date: March 2014 208KernelVersion: v3.15 209Contact: Linux power management list <linux-pm@vger.kernel.org> 210Description: 211 (RO) Display the target residency i.e. the minimum amount of 212 time (in microseconds) this cpu should spend in this idle state 213 to make the transition worth the effort. 214 215What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/s2idle/ 216Date: March 2018 217KernelVersion: v4.17 218Contact: Linux power management list <linux-pm@vger.kernel.org> 219Description: 220 Idle state usage statistics related to suspend-to-idle. 221 222 This attribute group is only present for states that can be 223 used in suspend-to-idle with suspended timekeeping. 224 225What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/s2idle/time 226Date: March 2018 227KernelVersion: v4.17 228Contact: Linux power management list <linux-pm@vger.kernel.org> 229Description: 230 Total time spent by the CPU in suspend-to-idle (with scheduler 231 tick suspended) after requesting this state. 232 233What: /sys/devices/system/cpu/cpuX/cpuidle/state<N>/s2idle/usage 234Date: March 2018 235KernelVersion: v4.17 236Contact: Linux power management list <linux-pm@vger.kernel.org> 237Description: 238 Total number of times this state has been requested by the CPU 239 while entering suspend-to-idle. 240 241What: /sys/devices/system/cpu/cpuX/cpufreq/* 242Date: pre-git history 243Contact: linux-pm@vger.kernel.org 244Description: Discover and change clock speed of CPUs 245 246 Clock scaling allows you to change the clock speed of the 247 CPUs on the fly. This is a nice method to save battery 248 power, because the lower the clock speed, the less power 249 the CPU consumes. 250 251 There are many knobs to tweak in this directory. 252 253 See files in Documentation/cpu-freq/ for more information. 254 255 256What: /sys/devices/system/cpu/cpuX/cpufreq/freqdomain_cpus 257Date: June 2013 258Contact: linux-pm@vger.kernel.org 259Description: Discover CPUs in the same CPU frequency coordination domain 260 261 freqdomain_cpus is the list of CPUs (online+offline) that share 262 the same clock/freq domain (possibly at the hardware level). 263 That information may be hidden from the cpufreq core and the 264 value of related_cpus may be different from freqdomain_cpus. This 265 attribute is useful for user space DVFS controllers to get better 266 power/performance results for platforms using acpi-cpufreq. 267 268 This file is only present if the acpi-cpufreq or the cppc-cpufreq 269 drivers are in use. 270 271 272What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1} 273Date: August 2008 274KernelVersion: 2.6.27 275Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 276Description: Disable L3 cache indices 277 278 These files exist in every CPU's cache/index3 directory. Each 279 cache_disable_{0,1} file corresponds to one disable slot which 280 can be used to disable a cache index. Reading from these files 281 on a processor with this functionality will return the currently 282 disabled index for that node. There is one L3 structure per 283 node, or per internal node on MCM machines. Writing a valid 284 index to one of these files will cause the specified cache 285 index to be disabled. 286 287 All AMD processors with L3 caches provide this functionality. 288 For details, see BKDGs at 289 https://www.amd.com/en/support/tech-docs?keyword=bios+kernel 290 291 292What: /sys/devices/system/cpu/cpufreq/boost 293Date: August 2012 294Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 295Description: Processor frequency boosting control 296 297 This switch controls the boost setting for the whole system. 298 Boosting allows the CPU and the firmware to run at a frequency 299 beyond its nominal limit. 300 301 More details can be found in 302 Documentation/admin-guide/pm/cpufreq.rst 303 304 305What: /sys/devices/system/cpu/cpuX/crash_notes 306 /sys/devices/system/cpu/cpuX/crash_notes_size 307Date: April 2013 308Contact: kexec@lists.infradead.org 309Description: address and size of the percpu note. 310 311 crash_notes: the physical address of the memory that holds the 312 note of cpuX. 313 314 crash_notes_size: size of the note of cpuX. 315 316 317What: /sys/devices/system/cpu/intel_pstate/max_perf_pct 318 /sys/devices/system/cpu/intel_pstate/min_perf_pct 319 /sys/devices/system/cpu/intel_pstate/no_turbo 320Date: February 2013 321Contact: linux-pm@vger.kernel.org 322Description: Parameters for the Intel P-state driver 323 324 Logic for selecting the current P-state in Intel 325 Sandybridge+ processors. The three knobs control 326 limits for the P-state that will be requested by the 327 driver. 328 329 max_perf_pct: limits the maximum P state that will be requested by 330 the driver stated as a percentage of the available performance. 331 332 min_perf_pct: limits the minimum P state that will be requested by 333 the driver stated as a percentage of the available performance. 334 335 no_turbo: limits the driver to selecting P states below the turbo 336 frequency range. 337 338 More details can be found in 339 Documentation/admin-guide/pm/intel_pstate.rst 340 341What: /sys/devices/system/cpu/cpu*/cache/index*/<set_of_attributes_mentioned_below> 342Date: July 2014(documented, existed before August 2008) 343Contact: Sudeep Holla <sudeep.holla@arm.com> 344 Linux kernel mailing list <linux-kernel@vger.kernel.org> 345Description: Parameters for the CPU cache attributes 346 347 allocation_policy: 348 - WriteAllocate: 349 allocate a memory location to a cache line 350 on a cache miss because of a write 351 - ReadAllocate: 352 allocate a memory location to a cache line 353 on a cache miss because of a read 354 - ReadWriteAllocate: 355 both writeallocate and readallocate 356 357 attributes: 358 LEGACY used only on IA64 and is same as write_policy 359 360 coherency_line_size: 361 the minimum amount of data in bytes that gets 362 transferred from memory to cache 363 364 level: 365 the cache hierarchy in the multi-level cache configuration 366 367 number_of_sets: 368 total number of sets in the cache, a set is a 369 collection of cache lines with the same cache index 370 371 physical_line_partition: 372 number of physical cache line per cache tag 373 374 shared_cpu_list: 375 the list of logical cpus sharing the cache 376 377 shared_cpu_map: 378 logical cpu mask containing the list of cpus sharing 379 the cache 380 381 size: 382 the total cache size in kB 383 384 type: 385 - Instruction: cache that only holds instructions 386 - Data: cache that only caches data 387 - Unified: cache that holds both data and instructions 388 389 ways_of_associativity: 390 degree of freedom in placing a particular block 391 of memory in the cache 392 393 write_policy: 394 - WriteThrough: 395 data is written to both the cache line 396 and to the block in the lower-level memory 397 - WriteBack: 398 data is written only to the cache line and 399 the modified cache line is written to main 400 memory only when it is replaced 401 402 403What: /sys/devices/system/cpu/cpu*/cache/index*/id 404Date: September 2016 405Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 406Description: Cache id 407 408 The id provides a unique number for a specific instance of 409 a cache of a particular type. E.g. there may be a level 410 3 unified cache on each socket in a server and we may 411 assign them ids 0, 1, 2, ... 412 413 Note that id value can be non-contiguous. E.g. level 1 414 caches typically exist per core, but there may not be a 415 power of two cores on a socket, so these caches may be 416 numbered 0, 1, 2, 3, 4, 5, 8, 9, 10, ... 417 418What: /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats 419 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/turbo_stat 420 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/sub_turbo_stat 421 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/unthrottle 422 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/powercap 423 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overtemp 424 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/supply_fault 425 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/overcurrent 426 /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats/occ_reset 427Date: March 2016 428Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 429 Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 430Description: POWERNV CPUFreq driver's frequency throttle stats directory and 431 attributes 432 433 'cpuX/cpufreq/throttle_stats' directory contains the CPU frequency 434 throttle stat attributes for the chip. The throttle stats of a cpu 435 is common across all the cpus belonging to a chip. Below are the 436 throttle attributes exported in the 'throttle_stats' directory: 437 438 - turbo_stat : This file gives the total number of times the max 439 frequency is throttled to lower frequency in turbo (at and above 440 nominal frequency) range of frequencies. 441 442 - sub_turbo_stat : This file gives the total number of times the 443 max frequency is throttled to lower frequency in sub-turbo(below 444 nominal frequency) range of frequencies. 445 446 - unthrottle : This file gives the total number of times the max 447 frequency is unthrottled after being throttled. 448 449 - powercap : This file gives the total number of times the max 450 frequency is throttled due to 'Power Capping'. 451 452 - overtemp : This file gives the total number of times the max 453 frequency is throttled due to 'CPU Over Temperature'. 454 455 - supply_fault : This file gives the total number of times the 456 max frequency is throttled due to 'Power Supply Failure'. 457 458 - overcurrent : This file gives the total number of times the 459 max frequency is throttled due to 'Overcurrent'. 460 461 - occ_reset : This file gives the total number of times the max 462 frequency is throttled due to 'OCC Reset'. 463 464 The sysfs attributes representing different throttle reasons like 465 powercap, overtemp, supply_fault, overcurrent and occ_reset map to 466 the reasons provided by OCC firmware for throttling the frequency. 467 468What: /sys/devices/system/cpu/cpufreq/policyX/throttle_stats 469 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/turbo_stat 470 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/sub_turbo_stat 471 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/unthrottle 472 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/powercap 473 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/overtemp 474 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/supply_fault 475 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/overcurrent 476 /sys/devices/system/cpu/cpufreq/policyX/throttle_stats/occ_reset 477Date: March 2016 478Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 479 Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 480Description: POWERNV CPUFreq driver's frequency throttle stats directory and 481 attributes 482 483 'policyX/throttle_stats' directory and all the attributes are same as 484 the /sys/devices/system/cpu/cpuX/cpufreq/throttle_stats directory and 485 attributes which give the frequency throttle information of the chip. 486 487What: /sys/devices/system/cpu/cpuX/regs/ 488 /sys/devices/system/cpu/cpuX/regs/identification/ 489 /sys/devices/system/cpu/cpuX/regs/identification/midr_el1 490 /sys/devices/system/cpu/cpuX/regs/identification/revidr_el1 491 /sys/devices/system/cpu/cpuX/regs/identification/smidr_el1 492Date: June 2016 493Contact: Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org> 494Description: AArch64 CPU registers 495 496 'identification' directory exposes the CPU ID registers for 497 identifying model and revision of the CPU and SMCU. 498 499What: /sys/devices/system/cpu/aarch32_el0 500Date: May 2021 501Contact: Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org> 502Description: Identifies the subset of CPUs in the system that can execute 503 AArch32 (32-bit ARM) applications. If present, the same format as 504 /sys/devices/system/cpu/{offline,online,possible,present} is used. 505 If absent, then all or none of the CPUs can execute AArch32 506 applications and execve() will behave accordingly. 507 508What: /sys/devices/system/cpu/cpuX/cpu_capacity 509Date: December 2016 510Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 511Description: information about CPUs heterogeneity. 512 513 cpu_capacity: capacity of cpuX. 514 515What: /sys/devices/system/cpu/vulnerabilities 516 /sys/devices/system/cpu/vulnerabilities/gather_data_sampling 517 /sys/devices/system/cpu/vulnerabilities/itlb_multihit 518 /sys/devices/system/cpu/vulnerabilities/l1tf 519 /sys/devices/system/cpu/vulnerabilities/mds 520 /sys/devices/system/cpu/vulnerabilities/meltdown 521 /sys/devices/system/cpu/vulnerabilities/mmio_stale_data 522 /sys/devices/system/cpu/vulnerabilities/retbleed 523 /sys/devices/system/cpu/vulnerabilities/spec_store_bypass 524 /sys/devices/system/cpu/vulnerabilities/spectre_v1 525 /sys/devices/system/cpu/vulnerabilities/spectre_v2 526 /sys/devices/system/cpu/vulnerabilities/srbds 527 /sys/devices/system/cpu/vulnerabilities/tsx_async_abort 528Date: January 2018 529Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 530Description: Information about CPU vulnerabilities 531 532 The files are named after the code names of CPU 533 vulnerabilities. The output of those files reflects the 534 state of the CPUs in the system. Possible output values: 535 536 ================ ============================================== 537 "Not affected" CPU is not affected by the vulnerability 538 "Vulnerable" CPU is affected and no mitigation in effect 539 "Mitigation: $M" CPU is affected and mitigation $M is in effect 540 ================ ============================================== 541 542 See also: Documentation/admin-guide/hw-vuln/index.rst 543 544What: /sys/devices/system/cpu/smt 545 /sys/devices/system/cpu/smt/active 546 /sys/devices/system/cpu/smt/control 547Date: June 2018 548Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 549Description: Control Symmetric Multi Threading (SMT) 550 551 active: Tells whether SMT is active (enabled and siblings online) 552 553 control: Read/write interface to control SMT. Possible 554 values: 555 556 ================ ========================================= 557 "on" SMT is enabled 558 "off" SMT is disabled 559 "<N>" SMT is enabled with N threads per core. 560 "forceoff" SMT is force disabled. Cannot be changed. 561 "notsupported" SMT is not supported by the CPU 562 "notimplemented" SMT runtime toggling is not 563 implemented for the architecture 564 ================ ========================================= 565 566 If control status is "forceoff" or "notsupported" writes 567 are rejected. 568 569What: /sys/devices/system/cpu/cpuX/power/energy_perf_bias 570Date: March 2019 571Contact: linux-pm@vger.kernel.org 572Description: Intel Energy and Performance Bias Hint (EPB) 573 574 EPB for the given CPU in a sliding scale 0 - 15, where a value 575 of 0 corresponds to a hint preference for highest performance 576 and a value of 15 corresponds to the maximum energy savings. 577 578 In order to change the EPB value for the CPU, write either 579 a number in the 0 - 15 sliding scale above, or one of the 580 strings: "performance", "balance-performance", "normal", 581 "balance-power", "power" (that represent values reflected by 582 their meaning), to this attribute. 583 584 This attribute is present for all online CPUs supporting the 585 Intel EPB feature. 586 587What: /sys/devices/system/cpu/umwait_control 588 /sys/devices/system/cpu/umwait_control/enable_c02 589 /sys/devices/system/cpu/umwait_control/max_time 590Date: May 2019 591Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 592Description: Umwait control 593 594 enable_c02: Read/write interface to control umwait C0.2 state 595 Read returns C0.2 state status: 596 0: C0.2 is disabled 597 1: C0.2 is enabled 598 599 Write 'y' or '1' or 'on' to enable C0.2 state. 600 Write 'n' or '0' or 'off' to disable C0.2 state. 601 602 The interface is case insensitive. 603 604 max_time: Read/write interface to control umwait maximum time 605 in TSC-quanta that the CPU can reside in either C0.1 606 or C0.2 state. The time is an unsigned 32-bit number. 607 Note that a value of zero means there is no limit. 608 Low order two bits must be zero. 609 610What: /sys/devices/system/cpu/svm 611Date: August 2019 612Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 613 Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 614Description: Secure Virtual Machine 615 616 If 1, it means the system is using the Protected Execution 617 Facility in POWER9 and newer processors. i.e., it is a Secure 618 Virtual Machine. 619 620What: /sys/devices/system/cpu/cpuX/purr 621Date: Apr 2005 622Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 623Description: PURR ticks for this CPU since the system boot. 624 625 The Processor Utilization Resources Register (PURR) is 626 a 64-bit counter which provides an estimate of the 627 resources used by the CPU thread. The contents of this 628 register increases monotonically. This sysfs interface 629 exposes the number of PURR ticks for cpuX. 630 631What: /sys/devices/system/cpu/cpuX/spurr 632Date: Dec 2006 633Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 634Description: SPURR ticks for this CPU since the system boot. 635 636 The Scaled Processor Utilization Resources Register 637 (SPURR) is a 64-bit counter that provides a frequency 638 invariant estimate of the resources used by the CPU 639 thread. The contents of this register increases 640 monotonically. This sysfs interface exposes the number 641 of SPURR ticks for cpuX. 642 643What: /sys/devices/system/cpu/cpuX/idle_purr 644Date: Apr 2020 645Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 646Description: PURR ticks for cpuX when it was idle. 647 648 This sysfs interface exposes the number of PURR ticks 649 for cpuX when it was idle. 650 651What: /sys/devices/system/cpu/cpuX/idle_spurr 652Date: Apr 2020 653Contact: Linux for PowerPC mailing list <linuxppc-dev@ozlabs.org> 654Description: SPURR ticks for cpuX when it was idle. 655 656 This sysfs interface exposes the number of SPURR ticks 657 for cpuX when it was idle. 658 659What: /sys/devices/system/cpu/cpuX/mte_tcf_preferred 660Date: July 2021 661Contact: Linux ARM Kernel Mailing list <linux-arm-kernel@lists.infradead.org> 662Description: Preferred MTE tag checking mode 663 664 When a user program specifies more than one MTE tag checking 665 mode, this sysfs node is used to specify which mode should 666 be preferred when scheduling a task on that CPU. Possible 667 values: 668 669 ================ ============================================== 670 "sync" Prefer synchronous mode 671 "asymm" Prefer asymmetric mode 672 "async" Prefer asynchronous mode 673 ================ ============================================== 674 675 See also: Documentation/arch/arm64/memory-tagging-extension.rst 676 677What: /sys/devices/system/cpu/nohz_full 678Date: Apr 2015 679Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 680Description: 681 (RO) the list of CPUs that are in nohz_full mode. 682 These CPUs are set by boot parameter "nohz_full=". 683 684What: /sys/devices/system/cpu/isolated 685Date: Apr 2015 686Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 687Description: 688 (RO) the list of CPUs that are isolated and don't 689 participate in load balancing. These CPUs are set by 690 boot parameter "isolcpus=". 691 692What: /sys/devices/system/cpu/crash_hotplug 693Date: Aug 2023 694Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> 695Description: 696 (RO) indicates whether or not the kernel directly supports 697 modifying the crash elfcorehdr for CPU hot un/plug and/or 698 on/offline changes. 699