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
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.
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:
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.
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.1-2001 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 set-
ting 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.
scope specified the value PTHREAD_SCOPE_PROCESS, which is not supported on Linux.
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.
pthread_attr_init(3), pthread_attr_setaffinity_np(3), pthread_attr_setinheritsched(3),
pthread_attr_setschedparam(3), pthread_attr_setschedpolicy(3), pthread_create(3),
This page is part of release 3.55 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
Linux 2013-04-19 PTHREAD_ATTR_SETSCOPE(3)