tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
cputopology.txt: standardize document format
Each text file under Documentation follows a different
format. Some doesn't even have titles!
Change its representation to follow the adopted standard,
using ReST markups for it to be parseable by Sphinx:
- Add a title for the document;
- mark literals;
- use table markup for existing table.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
authored by
Mauro Carvalho Chehab
and committed by
Jonathan Corbet
e8cb6f1e
09338fb0
+21
-14
+21
-14
Documentation/cputopology.txt
+21
-14
Documentation/cputopology.txt
···
1
+
===========================================
2
+
How CPU topology info is exported via sysfs
3
+
===========================================
1
4
2
5
Export CPU topology info via sysfs. Items (attributes) are similar
3
6
to /proc/cpuinfo output of some architectures:
···
78
75
they reflect the cpu and cache hierarchy.
79
76
80
77
For an architecture to support this feature, it must define some of
81
-
these macros in include/asm-XXX/topology.h:
82
-
#define topology_physical_package_id(cpu)
83
-
#define topology_core_id(cpu)
84
-
#define topology_book_id(cpu)
85
-
#define topology_drawer_id(cpu)
86
-
#define topology_sibling_cpumask(cpu)
87
-
#define topology_core_cpumask(cpu)
88
-
#define topology_book_cpumask(cpu)
89
-
#define topology_drawer_cpumask(cpu)
78
+
these macros in include/asm-XXX/topology.h::
90
79
91
-
The type of **_id macros is int.
92
-
The type of **_cpumask macros is (const) struct cpumask *. The latter
93
-
correspond with appropriate **_siblings sysfs attributes (except for
80
+
#define topology_physical_package_id(cpu)
81
+
#define topology_core_id(cpu)
82
+
#define topology_book_id(cpu)
83
+
#define topology_drawer_id(cpu)
84
+
#define topology_sibling_cpumask(cpu)
85
+
#define topology_core_cpumask(cpu)
86
+
#define topology_book_cpumask(cpu)
87
+
#define topology_drawer_cpumask(cpu)
88
+
89
+
The type of ``**_id macros`` is int.
90
+
The type of ``**_cpumask macros`` is ``(const) struct cpumask *``. The latter
91
+
correspond with appropriate ``**_siblings`` sysfs attributes (except for
94
92
topology_sibling_cpumask() which corresponds with thread_siblings).
95
93
96
94
To be consistent on all architectures, include/linux/topology.h
97
95
provides default definitions for any of the above macros that are
98
96
not defined by include/asm-XXX/topology.h:
97
+
99
98
1) physical_package_id: -1
100
99
2) core_id: 0
101
100
3) sibling_cpumask: just the given CPU
···
112
107
/sys/devices/system/cpu and includes these files. The internal
113
108
source for the output is in brackets ("[]").
114
109
110
+
=========== ==========================================================
115
111
kernel_max: the maximum CPU index allowed by the kernel configuration.
116
112
[NR_CPUS-1]
117
113
···
128
122
129
123
present: CPUs that have been identified as being present in the
130
124
system. [cpu_present_mask]
125
+
=========== ==========================================================
131
126
132
127
The format for the above output is compatible with cpulist_parse()
133
128
[see <linux/cpumask.h>]. Some examples follow.
···
136
129
In this example, there are 64 CPUs in the system but cpus 32-63 exceed
137
130
the kernel max which is limited to 0..31 by the NR_CPUS config option
138
131
being 32. Note also that CPUs 2 and 4-31 are not online but could be
139
-
brought online as they are both present and possible.
132
+
brought online as they are both present and possible::
140
133
141
134
kernel_max: 31
142
135
offline: 2,4-31,32-63
···
147
140
In this example, the NR_CPUS config option is 128, but the kernel was
148
141
started with possible_cpus=144. There are 4 CPUs in the system and cpu2
149
142
was manually taken offline (and is the only CPU that can be brought
150
-
online.)
143
+
online.)::
151
144
152
145
kernel_max: 127
153
146
offline: 2,4-127,128-143