| What: /sys/devices/system/cpu/ | |
| Date: pre-git history | |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> | |
| Description: | |
| A collection of both global and individual CPU attributes | |
| Individual CPU attributes are contained in subdirectories | |
| named by the kernel's logical CPU number, e.g.: | |
| /sys/devices/system/cpu/cpu#/ | |
| What: /sys/devices/system/cpu/kernel_max | |
| /sys/devices/system/cpu/offline | |
| /sys/devices/system/cpu/online | |
| /sys/devices/system/cpu/possible | |
| /sys/devices/system/cpu/present | |
| Date: December 2008 | |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> | |
| Description: CPU topology files that describe kernel limits related to | |
| hotplug. Briefly: | |
| kernel_max: the maximum cpu index allowed by the kernel | |
| configuration. | |
| offline: cpus that are not online because they have been | |
| HOTPLUGGED off or exceed the limit of cpus allowed by the | |
| kernel configuration (kernel_max above). | |
| online: cpus that are online and being scheduled. | |
| possible: cpus that have been allocated resources and can be | |
| brought online if they are present. | |
| present: cpus that have been identified as being present in | |
| the system. | |
| See Documentation/cputopology.txt for more information. | |
| What: /sys/devices/system/cpu/probe | |
| /sys/devices/system/cpu/release | |
| Date: November 2009 | |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> | |
| Description: Dynamic addition and removal of CPU's. This is not hotplug | |
| removal, this is meant complete removal/addition of the CPU | |
| from the system. | |
| probe: writes to this file will dynamically add a CPU to the | |
| system. Information written to the file to add CPU's is | |
| architecture specific. | |
| release: writes to this file dynamically remove a CPU from | |
| the system. Information writtento the file to remove CPU's | |
| is architecture specific. | |
| What: /sys/devices/system/cpu/cpu#/node | |
| Date: October 2009 | |
| Contact: Linux memory management mailing list <linux-mm@kvack.org> | |
| Description: Discover NUMA node a CPU belongs to | |
| When CONFIG_NUMA is enabled, a symbolic link that points | |
| to the corresponding NUMA node directory. | |
| For example, the following symlink is created for cpu42 | |
| in NUMA node 2: | |
| /sys/devices/system/cpu/cpu42/node2 -> ../../node/node2 | |
| What: /sys/devices/system/cpu/cpu#/topology/core_id | |
| /sys/devices/system/cpu/cpu#/topology/core_siblings | |
| /sys/devices/system/cpu/cpu#/topology/core_siblings_list | |
| /sys/devices/system/cpu/cpu#/topology/physical_package_id | |
| /sys/devices/system/cpu/cpu#/topology/thread_siblings | |
| /sys/devices/system/cpu/cpu#/topology/thread_siblings_list | |
| Date: December 2008 | |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> | |
| Description: CPU topology files that describe a logical CPU's relationship | |
| to other cores and threads in the same physical package. | |
| One cpu# directory is created per logical CPU in the system, | |
| e.g. /sys/devices/system/cpu/cpu42/. | |
| Briefly, the files above are: | |
| core_id: the CPU core ID of cpu#. Typically it is the | |
| hardware platform's identifier (rather than the kernel's). | |
| The actual value is architecture and platform dependent. | |
| core_siblings: internal kernel map of cpu#'s hardware threads | |
| within the same physical_package_id. | |
| core_siblings_list: human-readable list of the logical CPU | |
| numbers within the same physical_package_id as cpu#. | |
| physical_package_id: physical package id of cpu#. Typically | |
| corresponds to a physical socket number, but the actual value | |
| is architecture and platform dependent. | |
| thread_siblings: internel kernel map of cpu#'s hardware | |
| threads within the same core as cpu# | |
| thread_siblings_list: human-readable list of cpu#'s hardware | |
| threads within the same core as cpu# | |
| See Documentation/cputopology.txt for more information. | |
| What: /sys/devices/system/cpu/cpuidle/current_driver | |
| /sys/devices/system/cpu/cpuidle/current_governer_ro | |
| Date: September 2007 | |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> | |
| Description: Discover cpuidle policy and mechanism | |
| Various CPUs today support multiple idle levels that are | |
| differentiated by varying exit latencies and power | |
| consumption during idle. | |
| Idle policy (governor) is differentiated from idle mechanism | |
| (driver) | |
| current_driver: displays current idle mechanism | |
| current_governor_ro: displays current idle policy | |
| See files in Documentation/cpuidle/ for more information. | |
| What: /sys/devices/system/cpu/cpu#/cpufreq/* | |
| Date: pre-git history | |
| Contact: cpufreq@vger.kernel.org | |
| Description: Discover and change clock speed of CPUs | |
| Clock scaling allows you to change the clock speed of the | |
| CPUs on the fly. This is a nice method to save battery | |
| power, because the lower the clock speed, the less power | |
| the CPU consumes. | |
| There are many knobs to tweak in this directory. | |
| See files in Documentation/cpu-freq/ for more information. | |
| In particular, read Documentation/cpu-freq/user-guide.txt | |
| to learn how to control the knobs. | |
| What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1} | |
| Date: August 2008 | |
| KernelVersion: 2.6.27 | |
| Contact: discuss@x86-64.org | |
| Description: Disable L3 cache indices | |
| These files exist in every CPU's cache/index3 directory. Each | |
| cache_disable_{0,1} file corresponds to one disable slot which | |
| can be used to disable a cache index. Reading from these files | |
| on a processor with this functionality will return the currently | |
| disabled index for that node. There is one L3 structure per | |
| node, or per internal node on MCM machines. Writing a valid | |
| index to one of these files will cause the specificed cache | |
| index to be disabled. | |
| All AMD processors with L3 caches provide this functionality. | |
| For details, see BKDGs at | |
| http://developer.amd.com/documentation/guides/Pages/default.aspx | |
| What: /sys/devices/system/cpu/cpufreq/boost | |
| Date: August 2012 | |
| Contact: Linux kernel mailing list <linux-kernel@vger.kernel.org> | |
| Description: Processor frequency boosting control | |
| This switch controls the boost setting for the whole system. | |
| Boosting allows the CPU and the firmware to run at a frequency | |
| beyound it's nominal limit. | |
| More details can be found in Documentation/cpu-freq/boost.txt | |
| What: /sys/devices/system/cpu/cpu#/crash_notes | |
| /sys/devices/system/cpu/cpu#/crash_notes_size | |
| Date: April 2013 | |
| Contact: kexec@lists.infradead.org | |
| Description: address and size of the percpu note. | |
| crash_notes: the physical address of the memory that holds the | |
| note of cpu#. | |
| crash_notes_size: size of the note of cpu#. |