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pthread_attr_setscope(3) [osf1 man page]

pthread_attr_setscope(3)				     Library Functions Manual					  pthread_attr_setscope(3)

NAME
pthread_attr_setscope - Sets the contention scope attribute of the specified thread attributes object. LIBRARY
DECthreads POSIX 1003.1c Library (libpthread.so) SYNOPSIS
#include <pthread.h> int pthread_attr_setscope( pthread_attr_t *attr, int scope); STANDARDS
Interfaces documented on this reference page conform to industry standards as follows: IEEE Std 1003.1c-1995, POSIX System Application Program Interface PARAMETERS
Address of the thread attributes object whose contention scope attribute is to be modified. New value for the contention scope attribute of the thread attributes object specified by attr. DESCRIPTION
This routine uses the value specified in the scope argument to set the contention scope attribute of the thread attributes object specified in the attr argument. When creating a thread, use a thread attributes object to specify nondefault values for thread attributes. The contention scope attribute specifies the set of threads with which a thread must compete for processing resources. The contention scope attribute specifies whether the new thread competes for processing resources only with other threads in its own process, called process contention scope, or with all threads on the system, called system contention scope. On Tru64 UNIX, DECthreads supports both process contention scope and system contention scope threads. DECthreads selects at most one thread to execute on each processor at any point in time. DECthreads resolves the contention based on each thread's scheduling attributes (for example, priority) and scheduling policy (for example, round-robin). A thread created using a thread attributes object whose contention scope attribute is set to PTHREAD_SCOPE_PROCESS contends for processing resources with other threads within its own process that also were created with PTHREAD_SCOPE_PROCESS. It is unspecified how such threads are scheduled relative to threads in other processes or threads in the same process that were created with PTHREAD_SCOPE_SYSTEM contention scope. A thread created using a thread attributes object whose contention scope attribute is set to PTHREAD_SCOPE_SYSTEM contends for processing resources with other threads in any process that also were created with PTHREAD_SCOPE_SYSTEM. NOTES
The value of the contention scope attribute of a particular thread attributes object does not necessarily correspond to the actual schedul- ing contention scope of any existing thread in your multithreaded program. RETURN VALUES
If an error condition occurs, this routine returns an integer value indicating the type of error. Possible return values are as follows: Successful completion. The value specified by attr is not a valid thread attributes value, or the value specified by scope is not valid. An attempt was made to set the attribute to an unsupported value. ERRORS
None RELATED INFORMATION
Functions: pthread_attr_destroy(3), pthread_attr_init(3), pthread_attr_getscope(3), pthread_create(3) Manuals: Guide to DECthreads and Programmer's Guide delim off pthread_attr_setscope(3)

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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(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 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 schedul- ing 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 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 buf- fer 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 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.1-2001 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 3.53 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 2013-04-19 PTHREAD_ATTR_SETSCOPE(3)
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