| 1 | |
| 2 | Export cpu topology info via sysfs. Items (attributes) are similar |
| 3 | to /proc/cpuinfo. |
| 4 | |
| 5 | 1) /sys/devices/system/cpu/cpuX/topology/physical_package_id: |
| 6 | represent the physical package id of cpu X; |
| 7 | 2) /sys/devices/system/cpu/cpuX/topology/core_id: |
| 8 | represent the cpu core id to cpu X; |
| 9 | 3) /sys/devices/system/cpu/cpuX/topology/thread_siblings: |
| 10 | represent the thread siblings to cpu X in the same core; |
| 11 | 4) /sys/devices/system/cpu/cpuX/topology/core_siblings: |
| 12 | represent the thread siblings to cpu X in the same physical package; |
| 13 | |
| 14 | To implement it in an architecture-neutral way, a new source file, |
| 15 | drivers/base/topology.c, is to export the 4 attributes. |
| 16 | |
| 17 | For an architecture to support this feature, it must define some of |
| 18 | these macros in include/asm-XXX/topology.h: |
| 19 | #define topology_physical_package_id(cpu) |
| 20 | #define topology_core_id(cpu) |
| 21 | #define topology_thread_siblings(cpu) |
| 22 | #define topology_core_siblings(cpu) |
| 23 | |
| 24 | The type of **_id is int. |
| 25 | The type of siblings is cpumask_t. |
| 26 | |
| 27 | To be consistent on all architectures, include/linux/topology.h |
| 28 | provides default definitions for any of the above macros that are |
| 29 | not defined by include/asm-XXX/topology.h: |
| 30 | 1) physical_package_id: -1 |
| 31 | 2) core_id: 0 |
| 32 | 3) thread_siblings: just the given CPU |
| 33 | 4) core_siblings: just the given CPU |