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Diffstat (limited to 'kernel/Documentation/ABI/testing/sysfs-devices-system-cpu')
| -rw-r--r-- | kernel/Documentation/ABI/testing/sysfs-devices-system-cpu | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/kernel/Documentation/ABI/testing/sysfs-devices-system-cpu b/kernel/Documentation/ABI/testing/sysfs-devices-system-cpu new file mode 100644 index 000000000..da9551357 --- /dev/null +++ b/kernel/Documentation/ABI/testing/sysfs-devices-system-cpu @@ -0,0 +1,273 @@ +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: linux-pm@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#/cpufreq/freqdomain_cpus +Date: June 2013 +Contact: linux-pm@vger.kernel.org +Description: Discover CPUs in the same CPU frequency coordination domain + + freqdomain_cpus is the list of CPUs (online+offline) that share + the same clock/freq domain (possibly at the hardware level). + That information may be hidden from the cpufreq core and the + value of related_cpus may be different from freqdomain_cpus. This + attribute is useful for user space DVFS controllers to get better + power/performance results for platforms using acpi-cpufreq. + + This file is only present if the acpi-cpufreq driver is in use. + + +What: /sys/devices/system/cpu/cpu*/cache/index3/cache_disable_{0,1} +Date: August 2008 +KernelVersion: 2.6.27 +Contact: Linux kernel mailing list <linux-kernel@vger.kernel.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#. + + +What: /sys/devices/system/cpu/intel_pstate/max_perf_pct + /sys/devices/system/cpu/intel_pstate/min_perf_pct + /sys/devices/system/cpu/intel_pstate/no_turbo +Date: February 2013 +Contact: linux-pm@vger.kernel.org +Description: Parameters for the Intel P-state driver + + Logic for selecting the current P-state in Intel + Sandybridge+ processors. The three knobs control + limits for the P-state that will be requested by the + driver. + + max_perf_pct: limits the maximum P state that will be requested by + the driver stated as a percentage of the available performance. + + min_perf_pct: limits the minimum P state that will be requested by + the driver stated as a percentage of the available performance. + + no_turbo: limits the driver to selecting P states below the turbo + frequency range. + + More details can be found in Documentation/cpu-freq/intel-pstate.txt + +What: /sys/devices/system/cpu/cpu*/cache/index*/<set_of_attributes_mentioned_below> +Date: July 2014(documented, existed before August 2008) +Contact: Sudeep Holla <sudeep.holla@arm.com> + Linux kernel mailing list <linux-kernel@vger.kernel.org> +Description: Parameters for the CPU cache attributes + + allocation_policy: + - WriteAllocate: allocate a memory location to a cache line + on a cache miss because of a write + - ReadAllocate: allocate a memory location to a cache line + on a cache miss because of a read + - ReadWriteAllocate: both writeallocate and readallocate + + attributes: LEGACY used only on IA64 and is same as write_policy + + coherency_line_size: the minimum amount of data in bytes that gets + transferred from memory to cache + + level: the cache hierarcy in the multi-level cache configuration + + number_of_sets: total number of sets in the cache, a set is a + collection of cache lines with the same cache index + + physical_line_partition: number of physical cache line per cache tag + + shared_cpu_list: the list of logical cpus sharing the cache + + shared_cpu_map: logical cpu mask containing the list of cpus sharing + the cache + + size: the total cache size in kB + + type: + - Instruction: cache that only holds instructions + - Data: cache that only caches data + - Unified: cache that holds both data and instructions + + ways_of_associativity: degree of freedom in placing a particular block + of memory in the cache + + write_policy: + - WriteThrough: data is written to both the cache line + and to the block in the lower-level memory + - WriteBack: data is written only to the cache line and + the modified cache line is written to main + memory only when it is replaced |