1PTHREAD_ATTR_SETSCOPE(3)   Linux Programmer's Manual  PTHREAD_ATTR_SETSCOPE(3)
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NAME

6       pthread_attr_setscope, pthread_attr_getscope - set/get contention scope
7       attribute in thread attributes object
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SYNOPSIS

10       #include <pthread.h>
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12       int pthread_attr_setscope(pthread_attr_t *attr, int scope);
13       int pthread_attr_getscope(pthread_attr_t *attr, int *scope);
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15       Compile and link with -pthread.
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DESCRIPTION

18       The  pthread_attr_setscope()  function  sets   the   contention   scope
19       attribute  of  the  thread attributes object referred to by attr to the
20       value specified in scope.  The contention scope attribute  defines  the
21       set  of  threads  against which a thread competes for resources such as
22       the CPU.  POSIX.1-2001 specifies two possible values for scope:
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24       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
29              another according to their scheduling policy and priority.
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31       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.1-2001
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.
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42       POSIX.1-2001 only requires that an implementation support one of  these
43       contention  scopes,  but  permits both to be supported.  Linux supports
44       PTHREAD_SCOPE_SYSTEM, but not PTHREAD_SCOPE_PROCESS.
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46       The  pthread_attr_getscope()  function  returns  the  contention  scope
47       attribute  of  the  thread attributes object referred to by attr in the
48       buffer pointed to by scope.
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RETURN VALUE

51       On success, these functions return 0; on error, they return  a  nonzero
52       error number.
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ERRORS

55       pthread_attr_setscope() can fail with the following errors:
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57       EINVAL An invalid value was specified in scope.
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59       ENOTSUP
60              scope  specified  the  value PTHREAD_SCOPE_PROCESS, which is not
61              supported on Linux.
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CONFORMING TO

64       POSIX.1-2001.
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NOTES

67       The PTHREAD_SCOPE_SYSTEM contention scope typically  indicates  that  a
68       userspace  thread  is  bound  directly  to  a  single kernel-scheduling
69       entity.  This is the case on Linux for the obsolete LinuxThreads imple‐
70       mentation  and  the  modern  NPTL  implementation,  which  are both 1:1
71       threading implementations.
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73       POSIX.1-2001 specifies that the default contention scope is implementa‐
74       tion-defined.
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SEE ALSO

77       pthread_attr_init(3), pthread_attr_setaffinity_np(3), pthread_attr_set‐
78       inheritsched(3), pthread_attr_setschedparam(3),  pthread_attr_setsched‐
79       policy(3), pthread_create(3), pthreads(7)
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COLOPHON

82       This  page  is  part of release 3.25 of the Linux man-pages project.  A
83       description of the project, and information about reporting  bugs,  can
84       be found at http://www.kernel.org/doc/man-pages/.
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88Linux                             2008-10-24          PTHREAD_ATTR_SETSCOPE(3)
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