pthread_attr_getscope(3) [osf1 man page]

pthread_attr_getscope(3)				     Library Functions Manual					  pthread_attr_getscope(3)

NAME

       pthread_attr_getscope - Obtains 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_getscope(
			const 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 obtained.  Receives the value of the contention scope attribute
       of the thread attributes object specified by attr.

DESCRIPTION

       This routine obtains the value of the contention scope attribute of the thread attributes object specified in the attr argument and  stores
       it  in  the location specified by the scope argument.  The specified attributes object must already be initialized at the time this routine
       is called.

       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.

       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 object.  This routine is not supported by the imple-
       mentation.

ERRORS

       None

RELATED INFORMATION

       Functions: pthread_attr_init(3), pthread_attr_setscope(3)

       Manuals: Guide to DECthreads and Programmer's Guide

       delim off

															  pthread_attr_getscope(3)

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)