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   pthread_attr_setscope    ( 3 )

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Имя (Name)

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

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Синопсис (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.

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Описание (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_EXPLICIT_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.

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Возвращаемое значение (Return value)

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

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Ошибки (Error)

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.

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Атрибуты (Attributes)

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

       ┌──────────────────────────────────────┬───────────────┬─────────┐
       │Interface                             │ Attribute     │ Value   │
       ├──────────────────────────────────────┼───────────────┼─────────┤
       │pthread_attr_setscope(),              │ Thread safety │ MT-Safe │
       │pthread_attr_getscope()               │               │         │
       └──────────────────────────────────────┴───────────────┴─────────┘

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Стандарты (Conforming to)

POSIX.1-2001, POSIX.1-2008.

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Примечание (Note)

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.

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Смотри также (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)

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