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



NAME
       pthread_attr_setscope, pthread_attr_getscope - set/get contention scope attribute in thread attributes object

SYNOPSIS
       #include <pthread.h>

       int pthread_attr_setscope(pthread_attr_t *attr, int scope);
       int pthread_attr_getscope(pthread_attr_t *attr, int *scope);

       Compile and link with -pthread.

DESCRIPTION
       The  pthread_attr_setscope()  function sets the contention scope attribute of the thread attributes object referred to by
       attr to the value specified in scope.  The contention scope attribute defines the set of threads against which  a  thread
       competes for resources such as the CPU.  POSIX.1-2001 specifies two possible values for scope:

       PTHREAD_SCOPE_SYSTEM
              The  thread  competes  for  resources  with  all other threads in all processes on the system that are in the same
              scheduling allocation domain (a group of one or more processors).  PTHREAD_SCOPE_SYSTEM threads are scheduled rel-
              ative to one another according to their scheduling policy and priority.

       PTHREAD_SCOPE_PROCESS
              The  thread  competes  for  resources  with  all other threads in the same process that were also created with the
              PTHREAD_SCOPE_PROCESS contention scope.  PTHREAD_SCOPE_PROCESS threads are scheduled relative to other threads  in
              the  process  according  to  their  scheduling  policy and priority.  POSIX.1-2001 leaves it unspecified how these
              threads contend with other threads in other process on the system or with other threads in the same  process  that
              were created with the PTHREAD_SCOPE_SYSTEM contention scope.

       POSIX.1-2001  only  requires  that  an implementation support one of these contention scopes, but permits both to be sup-
       ported.  Linux supports PTHREAD_SCOPE_SYSTEM, but not PTHREAD_SCOPE_PROCESS.

       The pthread_attr_getscope() function returns the contention scope attribute of the thread attributes object  referred  to
       by attr in the buffer pointed to by scope.

RETURN VALUE
       On success, these functions return 0; on error, they return a nonzero error number.

ERRORS
       pthread_attr_setscope() can fail with the following errors:

       EINVAL An invalid value was specified in scope.

       ENOTSUP
              scope specified the value PTHREAD_SCOPE_PROCESS, which is not supported on Linux.

CONFORMING TO
       POSIX.1-2001.

NOTES
       The  PTHREAD_SCOPE_SYSTEM contention scope typically indicates that a userspace thread is bound directly to a single ker-
       nel-scheduling entity.  This is the case on Linux for the obsolete LinuxThreads implementation and the modern NPTL imple-
       mentation, which are both 1:1 threading implementations.

       POSIX.1-2001 specifies that the default contention scope is implementation-defined.

SEE ALSO
       pthread_attr_init(3),   pthread_attr_setaffinity_np(3),  pthread_attr_setinheritsched(3),  pthread_attr_setschedparam(3),
       pthread_attr_setschedpolicy(3), pthread_create(3), pthreads(7)

COLOPHON
       This page is part of release 3.25 of the Linux man-pages project.  A description of the project,  and  information  about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2008-10-24                                   PTHREAD_ATTR_SETSCOPE(3)