Documentation: ABI: /sys/devices/system/cpu/cpu#/ topology files (663fb2fc) · Commits · e / devices / android_kernel_teracube_2e

Documentation/ABI/testing/sysfs-devices-system-cpu

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		@@ -38,6 +38,45 @@ Description: CPU topology files that describe kernel limits related to
		See Documentation/cputopology.txt for more information.


		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/cpu/cache/index/cache_disable_X
		Date: August 2008
		KernelVersion: 2.6.27

Documentation/cputopology.txt

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		Export cpu topology info via sysfs. Items (attributes) are similar
		Export CPU topology info via sysfs. Items (attributes) are similar
		to /proc/cpuinfo.

		1) /sys/devices/system/cpu/cpuX/topology/physical_package_id:
		represent the physical package id of cpu X;

		physical package id of cpuX. Typically corresponds to a physical
		socket number, but the actual value is architecture and platform
		dependent.

		2) /sys/devices/system/cpu/cpuX/topology/core_id:
		represent the cpu core id to cpu X;

		the CPU core ID of cpuX. Typically it is the hardware platform's
		identifier (rather than the kernel's). The actual value is
		architecture and platform dependent.

		3) /sys/devices/system/cpu/cpuX/topology/thread_siblings:
		represent the thread siblings to cpu X in the same core;

		internel kernel map of cpuX's hardware threads within the same
		core as cpuX

		4) /sys/devices/system/cpu/cpuX/topology/core_siblings:
		represent the thread siblings to cpu X in the same physical package;

		internal kernel map of cpuX's hardware threads within the same
		physical_package_id.

		To implement it in an architecture-neutral way, a new source file,
		drivers/base/topology.c, is to export the 4 attributes.
		@@ -32,32 +45,32 @@ not defined by include/asm-XXX/topology.h:
		3) thread_siblings: just the given CPU
		4) core_siblings: just the given CPU

		Additionally, cpu topology information is provided under
		Additionally, CPU topology information is provided under
		/sys/devices/system/cpu and includes these files. The internal
		source for the output is in brackets ("[]").

		kernel_max: the maximum cpu index allowed by the kernel configuration.
		kernel_max: the maximum CPU index allowed by the kernel configuration.
		[NR_CPUS-1]

		offline: cpus that are not online because they have been
		offline: CPUs that are not online because they have been
		HOTPLUGGED off (see cpu-hotplug.txt) or exceed the limit
		of cpus allowed by the kernel configuration (kernel_max
		of CPUs allowed by the kernel configuration (kernel_max
		above). [~cpu_online_mask + cpus >= NR_CPUS]

		online: cpus that are online and being scheduled [cpu_online_mask]
		online: CPUs that are online and being scheduled [cpu_online_mask]

		possible: cpus that have been allocated resources and can be
		possible: CPUs that have been allocated resources and can be
		brought online if they are present. [cpu_possible_mask]

		present: cpus that have been identified as being present in the
		present: CPUs that have been identified as being present in the
		system. [cpu_present_mask]

		The format for the above output is compatible with cpulist_parse()
		[see <linux/cpumask.h>]. Some examples follow.

		In this example, there are 64 cpus in the system but cpus 32-63 exceed
		In this example, there are 64 CPUs in the system but cpus 32-63 exceed
		the kernel max which is limited to 0..31 by the NR_CPUS config option
		being 32. Note also that cpus 2 and 4-31 are not online but could be
		being 32. Note also that CPUs 2 and 4-31 are not online but could be
		brought online as they are both present and possible.

		kernel_max: 31
		@@ -67,8 +80,8 @@ brought online as they are both present and possible.
		present: 0-31

		In this example, the NR_CPUS config option is 128, but the kernel was
		started with possible_cpus=144. There are 4 cpus in the system and cpu2
		was manually taken offline (and is the only cpu that can be brought
		started with possible_cpus=144. There are 4 CPUs in the system and cpu2
		was manually taken offline (and is the only CPU that can be brought
		online.)

		kernel_max: 127
		@@ -78,4 +91,4 @@ online.)
		present: 0-3

		See cpu-hotplug.txt for the possible_cpus=NUM kernel start parameter
		as well as more information on the various cpumask's.
		as well as more information on the various cpumasks.