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#/cpufreq/freqdomain_cpus
  Date:		June 2013
  Contact:	cpufreq@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:	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#.
  
  
  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