1PTHREAD_ATTR_SETSCOPE(3) Linux Programmer's Manual PTHREAD_ATTR_SETSCOPE(3)
2
6 pthread_attr_setscope, pthread_attr_getscope - set/get contention scope
7 attribute in thread attributes object
8
10 #include <pthread.h>
11 int pthread_attr_setscope(pthread_attr_t *attr, int scope);
13 int pthread_attr_getscope(const pthread_attr_t *restrict attr,
14 int *restrict scope);
15 Compile and link with -pthread.
17
19 The pthread_attr_setscope() function sets the contention scope attri‐
20 bute of the thread attributes object referred to by attr to the value
21 specified in scope. The contention scope attribute defines the set of
22 threads against which a thread competes for resources such as the CPU.
23 POSIX.1 specifies two possible values for scope:
24 PTHREAD_SCOPE_SYSTEM
26 The thread competes for resources with all other threads in all
27 processes on the system that are in the same scheduling alloca‐
28 tion domain (a group of one or more processors).
29 PTHREAD_SCOPE_SYSTEM threads are scheduled relative to one an‐
30 other according to their scheduling policy and priority.
31 PTHREAD_SCOPE_PROCESS
33 The thread competes for resources with all other threads in the
34 same process that were also created with the
35 PTHREAD_SCOPE_PROCESS contention scope. PTHREAD_SCOPE_PROCESS
36 threads are scheduled relative to other threads in the process
37 according to their scheduling policy and priority. POSIX.1
38 leaves it unspecified how these threads contend with other
39 threads in other process on the system or with other threads in
40 the same process that were created with the PTHREAD_SCOPE_SYSTEM
41 contention scope.
42 POSIX.1 requires that an implementation support at least one of these
44 contention scopes. Linux supports PTHREAD_SCOPE_SYSTEM, but not
45 PTHREAD_SCOPE_PROCESS.
46 On systems that support multiple contention scopes, then, in order for
48 the parameter setting made by pthread_attr_setscope() to have effect
49 when calling pthread_create(3), the caller must use pthread_attr_set‐
50 inheritsched(3) to set the inherit-scheduler attribute of the at‐
51 tributes object attr to PTHREAD_EXPLICIT_SCHED.
52 The pthread_attr_getscope() function returns the contention scope at‐
54 tribute of the thread attributes object referred to by attr in the buf‐
55 fer pointed to by scope.
56
58 On success, these functions return 0; on error, they return a nonzero
59 error number.
60
62 pthread_attr_setscope() can fail with the following errors:
63 EINVAL An invalid value was specified in scope.
65 ENOTSUP
67 scope specified the value PTHREAD_SCOPE_PROCESS, which is not
68 supported on Linux.
69
71 For an explanation of the terms used in this section, see at‐
72 tributes(7).
73 ┌────────────────────────────────────────────┬───────────────┬─────────┐
75 │Interface │ Attribute │ Value │
76 ├────────────────────────────────────────────┼───────────────┼─────────┤
77 │pthread_attr_setscope(), │ Thread safety │ MT-Safe │
78 │pthread_attr_getscope() │ │ │
79 └────────────────────────────────────────────┴───────────────┴─────────┘
80
82 POSIX.1-2001, POSIX.1-2008.
83
85 The PTHREAD_SCOPE_SYSTEM contention scope typically indicates that a
86 user-space thread is bound directly to a single kernel-scheduling enti‐
87 ty. This is the case on Linux for the obsolete LinuxThreads implemen‐
88 tation and the modern NPTL implementation, which are both 1:1 threading
89 implementations.
90 POSIX.1 specifies that the default contention scope is implementation-
92 defined.
93
95 pthread_attr_init(3), pthread_attr_setaffinity_np(3),
96 pthread_attr_setinheritsched(3), pthread_attr_setschedparam(3),
97 pthread_attr_setschedpolicy(3), pthread_create(3), pthreads(7)
98
100 This page is part of release 5.12 of the Linux man-pages project. A
101 description of the project, information about reporting bugs, and the
102 latest version of this page, can be found at
103 https://www.kernel.org/doc/man-pages/.
104Linux 2021-03-22 PTHREAD_ATTR_SETSCOPE(3)