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author | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-15 12:58:58 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-15 12:58:58 -0700 |
commit | 486088bc4689f826b80aa317b45ac9e42e8b25ee (patch) | |
tree | adf5847a6119d24da990d9e336f005c4a316e6be /Documentation/cputopology.txt | |
parent | 52f6c588c77b76d548201470c2a28263a41b462b (diff) | |
parent | 43e5f7e1fa66531777c49791014c3124ea9208d8 (diff) |
Merge tag 'standardize-docs' of git://git.lwn.net/linux
Pull documentation format standardization from Jonathan Corbet:
"This series converts a number of top-level documents to the RST format
without incorporating them into the Sphinx tree. The hope is to bring
some uniformity to kernel documentation and, perhaps more importantly,
have our existing docs serve as an example of the desired formatting
for those that will be added later.
Mauro has gone through and fixed up a lot of top-level documentation
files to make them conform to the RST format, but without moving or
renaming them in any way. This will help when we incorporate the ones
we want to keep into the Sphinx doctree, but the real purpose is to
bring a bit of uniformity to our documentation and let the top-level
docs serve as examples for those writing new ones"
* tag 'standardize-docs' of git://git.lwn.net/linux: (84 commits)
docs: kprobes.txt: Fix whitespacing
tee.txt: standardize document format
cgroup-v2.txt: standardize document format
dell_rbu.txt: standardize document format
zorro.txt: standardize document format
xz.txt: standardize document format
xillybus.txt: standardize document format
vfio.txt: standardize document format
vfio-mediated-device.txt: standardize document format
unaligned-memory-access.txt: standardize document format
this_cpu_ops.txt: standardize document format
svga.txt: standardize document format
static-keys.txt: standardize document format
smsc_ece1099.txt: standardize document format
SM501.txt: standardize document format
siphash.txt: standardize document format
sgi-ioc4.txt: standardize document format
SAK.txt: standardize document format
rpmsg.txt: standardize document format
robust-futexes.txt: standardize document format
...
Diffstat (limited to 'Documentation/cputopology.txt')
-rw-r--r-- | Documentation/cputopology.txt | 37 |
1 files changed, 22 insertions, 15 deletions
diff --git a/Documentation/cputopology.txt b/Documentation/cputopology.txt index 127c9d8c2174..c6e7e9196a8b 100644 --- a/Documentation/cputopology.txt +++ b/Documentation/cputopology.txt @@ -1,3 +1,6 @@ +=========================================== +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: @@ -75,24 +78,26 @@ CONFIG_SCHED_BOOK and CONFIG_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_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_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 +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_drawer_id(cpu) + #define topology_sibling_cpumask(cpu) + #define topology_core_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) physical_package_id: -1 2) core_id: 0 3) sibling_cpumask: just the given CPU @@ -107,6 +112,7 @@ 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] @@ -122,6 +128,7 @@ source for the output is in brackets ("[]"). 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. @@ -129,7 +136,7 @@ The format for the above output is compatible with cpulist_parse() 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. +brought online as they are both present and possible:: kernel_max: 31 offline: 2,4-31,32-63 @@ -140,7 +147,7 @@ brought online as they are both present and possible. 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.) +online.):: kernel_max: 127 offline: 2,4-127,128-143 |