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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
PTHREAD_ATTR_SETSCOPE(3) Linux Programmer's Manual PTHREAD_ATTR_SETSCOPE(3)
pthread_attr_setscope, pthread_attr_getscope - set/get contention
scope attribute in thread attributes object
#include <pthread.h>
int pthread_attr_setscope(pthread_attr_t *attr, int scope);
int pthread_attr_getscope(const pthread_attr_t *attr, int *scope);
Compile and link with -pthread.
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.
On success, these functions return 0; on error, they return a nonzero
error number.
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.
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() │ │ │
└─────────────────────────┴───────────────┴─────────┘
POSIX.1-2001, POSIX.1-2008.
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.
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)
This page is part of release 4.12 of the Linux man-pages project. A
description of the project, information about reporting bugs, and the
latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2015-08-08 PTHREAD_ATTR_SETSCOPE(3)
Pages that refer to this page: pthread_attr_init(3), pthread_attr_setinheritsched(3), pthread_getattr_default_np(3), pthread_getattr_np(3), pthread_setconcurrency(3)