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Diffstat (limited to 'Documentation/cputopology.txt')
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diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt deleted file mode 100644 index 902d3151f527..000000000000 --- a/Documentation/cputopology.txt +++ /dev/null @@ -1,111 +0,0 @@ - -Export CPU topology info via sysfs. Items (attributes) are similar -to /proc/cpuinfo. - -1) /sys/devices/system/cpu/cpuX/topology/physical_package_id: - - 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: - - 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/book_id: - - the book ID of cpuX. Typically it is the hardware platform's - identifier (rather than the kernel's). The actual value is - architecture and platform dependent. - -4) /sys/devices/system/cpu/cpuX/topology/thread_siblings: - - internel kernel map of cpuX's hardware threads within the same - core as cpuX - -5) /sys/devices/system/cpu/cpuX/topology/core_siblings: - - internal kernel map of cpuX's hardware threads within the same - physical_package_id. - -6) /sys/devices/system/cpu/cpuX/topology/book_siblings: - - internal kernel map of cpuX's hardware threads within the same - book_id. - -To implement it in an architecture-neutral way, a new source file, -drivers/base/topology.c, is to export the 4 or 6 attributes. The two book -related sysfs files will only be created if CONFIG_SCHED_BOOK is selected. - -For an architecture to support this feature, it must define some of -these macros in include/asm-XXX/topology.h: -#define topology_physical_package_id(cpu) -#define topology_core_id(cpu) -#define topology_book_id(cpu) -#define topology_thread_cpumask(cpu) -#define topology_core_cpumask(cpu) -#define topology_book_cpumask(cpu) - -The type of **_id is int. -The type of siblings is (const) struct cpumask *. - -To be consistent on all architectures, include/linux/topology.h -provides default definitions for any of the above macros that are -not defined by include/asm-XXX/topology.h: -1) physical_package_id: -1 -2) core_id: 0 -3) thread_siblings: just the given CPU -4) core_siblings: just the given CPU - -For architectures that don't support books (CONFIG_SCHED_BOOK) there are no -default definitions for topology_book_id() and topology_book_cpumask(). - -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. - [NR_CPUS-1] - - 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 - above). [~cpu_online_mask + cpus >= NR_CPUS] - - online: CPUs that are online and being scheduled [cpu_online_mask] - - 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 - 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 -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 -brought online as they are both present and possible. - - kernel_max: 31 - offline: 2,4-31,32-63 - online: 0-1,3 - possible: 0-31 - 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 -online.) - - kernel_max: 127 - offline: 2,4-127,128-143 - online: 0-1,3 - possible: 0-127 - present: 0-3 - -See cpu-hotplug.txt for the possible_cpus=NUM kernel start parameter -as well as more information on the various cpumasks. |