123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177 |
- ===========================================
- How CPU topology info is exported via sysfs
- ===========================================
- Export CPU topology info via sysfs. Items (attributes) are similar
- to /proc/cpuinfo output of some architectures. They reside in
- /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.
- die_id:
- the CPU die ID of cpuX. Typically it is the hardware platform's
- identifier (rather than the kernel's). The actual value is
- architecture and platform dependent.
- 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.
- 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.
- drawer_id:
- the drawer ID of cpuX. Typically it is the hardware platform's
- identifier (rather than the kernel's). The actual value is
- architecture and platform dependent.
- core_cpus:
- internal kernel map of CPUs within the same core.
- (deprecated name: "thread_siblings")
- core_cpus_list:
- human-readable list of CPUs within the same core.
- (deprecated name: "thread_siblings_list");
- package_cpus:
- internal kernel map of the CPUs sharing the same physical_package_id.
- (deprecated name: "core_siblings")
- package_cpus_list:
- human-readable list of CPUs sharing the same physical_package_id.
- (deprecated name: "core_siblings_list")
- die_cpus:
- internal kernel map of CPUs within the same die.
- die_cpus_list:
- human-readable list of CPUs within the same die.
- book_siblings:
- internal kernel map of cpuX's hardware threads within the same
- book_id.
- book_siblings_list:
- human-readable list of cpuX's hardware threads within the same
- book_id.
- drawer_siblings:
- internal kernel map of cpuX's hardware threads within the same
- drawer_id.
- drawer_siblings_list:
- human-readable list of cpuX's hardware threads within the same
- drawer_id.
- Architecture-neutral, drivers/base/topology.c, exports these attributes.
- However, the book and drawer related sysfs files will only be created if
- CONFIG_SCHED_BOOK and CONFIG_SCHED_DRAWER are selected, respectively.
- CONFIG_SCHED_BOOK and CONFIG_SCHED_DRAWER are currently only used on s390,
- where they reflect the cpu and cache hierarchy.
- 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_die_id(cpu)
- #define topology_core_id(cpu)
- #define topology_book_id(cpu)
- #define topology_drawer_id(cpu)
- #define topology_sibling_cpumask(cpu)
- #define topology_core_cpumask(cpu)
- #define topology_die_cpumask(cpu)
- #define topology_book_cpumask(cpu)
- #define topology_drawer_cpumask(cpu)
- The type of ``**_id macros`` is int.
- The type of ``**_cpumask macros`` is ``(const) struct cpumask *``. The latter
- correspond with appropriate ``**_siblings`` sysfs attributes (except for
- topology_sibling_cpumask() which corresponds with thread_siblings).
- 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) topology_physical_package_id: -1
- 2) topology_die_id: -1
- 3) topology_core_id: 0
- 4) topology_sibling_cpumask: just the given CPU
- 5) topology_core_cpumask: just the given CPU
- 6) topology_die_cpumask: 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().
- For architectures that don't support drawers (CONFIG_SCHED_DRAWER) there are
- no default definitions for topology_drawer_id() and topology_drawer_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.
|