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Old 09-13-2006
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Sorry, i may be posting the wrong question in this forum... but just curious, suppose we have a set of pre-emptively scheduled processes. A process, B, is multi-threaded with user-level thread scheduling. If one of the threads has a long calculation before making a thread library call, does this mean other processes will have to wait? What happens in the schedulers?
 
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LEARN ABOUT OSF1

pthread_attr_setscope

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)