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 *attr, int *scope);
14 Compile and link with -pthread.
16
18 The pthread_attr_setscope() function sets the contention scope attri‐
19 bute of the thread attributes object referred to by attr to the value
20 specified in scope. The contention scope attribute defines the set of
21 threads against which a thread competes for resources such as the CPU.
22 POSIX.1 specifies two possible values for scope:
23 PTHREAD_SCOPE_SYSTEM
25 The thread competes for resources with all other threads in all
26 processes on the system that are in the same scheduling alloca‐
27 tion domain (a group of one or more processors).
28 PTHREAD_SCOPE_SYSTEM threads are scheduled relative to one an‐
29 other according to their scheduling policy and priority.
30 PTHREAD_SCOPE_PROCESS
32 The thread competes for resources with all other threads in the
33 same process that were also created with the
34 PTHREAD_SCOPE_PROCESS contention scope. PTHREAD_SCOPE_PROCESS
35 threads are scheduled relative to other threads in the process
36 according to their scheduling policy and priority. POSIX.1
37 leaves it unspecified how these threads contend with other
38 threads in other process on the system or with other threads in
39 the same process that were created with the PTHREAD_SCOPE_SYSTEM
40 contention scope.
41 POSIX.1 requires that an implementation support at least one of these
43 contention scopes. Linux supports PTHREAD_SCOPE_SYSTEM, but not
44 PTHREAD_SCOPE_PROCESS.
45 On systems that support multiple contention scopes, then, in order for
47 the parameter setting made by pthread_attr_setscope() to have effect
48 when calling pthread_create(3), the caller must use pthread_attr_set‐
49 inheritsched(3) to set the inherit-scheduler attribute of the at‐
50 tributes object attr to PTHREAD_EXPLICIT_SCHED.
51 The pthread_attr_getscope() function returns the contention scope at‐
53 tribute of the thread attributes object referred to by attr in the buf‐
54 fer pointed to by scope.
55
57 On success, these functions return 0; on error, they return a nonzero
58 error number.
59
61 pthread_attr_setscope() can fail with the following errors:
62 EINVAL An invalid value was specified in scope.
64 ENOTSUP
66 scope specified the value PTHREAD_SCOPE_PROCESS, which is not
67 supported on Linux.
68
70 For an explanation of the terms used in this section, see at‐
71 tributes(7).
72 ┌─────────────────────────┬───────────────┬─────────┐
74 │Interface │ Attribute │ Value │
75 ├─────────────────────────┼───────────────┼─────────┤
76 │pthread_attr_setscope(), │ Thread safety │ MT-Safe │
77 │pthread_attr_getscope() │ │ │
78 └─────────────────────────┴───────────────┴─────────┘
80 POSIX.1-2001, POSIX.1-2008.
81
83 The PTHREAD_SCOPE_SYSTEM contention scope typically indicates that a
84 user-space thread is bound directly to a single kernel-scheduling en‐
85 tity. This is the case on Linux for the obsolete LinuxThreads imple‐
86 mentation and the modern NPTL implementation, which are both 1:1
87 threading implementations.
88 POSIX.1 specifies that the default contention scope is implementation-
90 defined.
91
93 pthread_attr_init(3), pthread_attr_setaffinity_np(3),
94 pthread_attr_setinheritsched(3), pthread_attr_setschedparam(3),
95 pthread_attr_setschedpolicy(3), pthread_create(3), pthreads(7)
96
98 This page is part of release 5.10 of the Linux man-pages project. A
99 description of the project, information about reporting bugs, and the
100 latest version of this page, can be found at
101 https://www.kernel.org/doc/man-pages/.
102Linux 2017-09-15 PTHREAD_ATTR_SETSCOPE(3)