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