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Diffstat (limited to 'Documentation/cputopology.txt')
-rw-r--r-- | Documentation/cputopology.txt | 33 |
1 files changed, 33 insertions, 0 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt new file mode 100644 index 0000000..bd699da --- /dev/null +++ b/Documentation/cputopology.txt @@ -0,0 +1,33 @@ + +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; +2) /sys/devices/system/cpu/cpuX/topology/core_id: +represent the cpu core id to cpu X; +3) /sys/devices/system/cpu/cpuX/topology/thread_siblings: +represent the thread siblings to cpu X in the same core; +4) /sys/devices/system/cpu/cpuX/topology/core_siblings: +represent the thread siblings to cpu X in the same physical package; + +To implement it in an architecture-neutral way, a new source file, +drivers/base/topology.c, is to export the 4 attributes. + +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_thread_siblings(cpu) +#define topology_core_siblings(cpu) + +The type of **_id is int. +The type of siblings is cpumask_t. + +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 |