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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(const pthread_attr_t *restrict attr,
                                 int *restrict 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 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 relative 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 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 requires that an implementation support at least one of these contention scopes.  Linux supports PTHREAD_SCOPE_SYSTEM, but not PTHREAD_SCOPE_PROCESS.

       On  systems  that  support  multiple  contention  scopes,  then,  in  order for the parameter setting made by pthread_attr_setscope() to have effect when calling
       pthread_create(3), the caller must use pthread_attr_setinheritsched(3) to set the inherit-scheduler attribute  of  the  attributes  object  attr  to  PTHREAD_EX‐
       PLICIT_SCHED.

       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.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       β”Œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”¬β”€β”€β”€β”€β”€β”€β”€β”€β”€β”
       β”‚Interface                                                                                                                             β”‚ Attribute     β”‚ Value   β”‚
       β”œβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”Όβ”€β”€β”€β”€β”€β”€β”€β”€β”€β”€
       β”‚pthread_attr_setscope(), pthread_attr_getscope()                                                                                      β”‚ Thread safety β”‚ MT-Safe β”‚
       β””β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”€β”΄β”€β”€β”€β”€β”€β”€β”€β”€β”€β”˜

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008.

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

       POSIX.1 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)

Linux                                                                          2021-03-22                                                       PTHREAD_ATTR_SETSCOPE(3)