Section (3) pthread_attr_setscope
pthread_attr_setscope, pthread_attr_getscope — set/get contention scope attribute in thread attributes object
||const pthread_attr_t *attr,|
Compile and link with
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
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_SYSTEMthreads 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_PROCESSthreads 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
POSIX.1 requires that an implementation support at least
one of these contention scopes. Linux supports
PTHREAD_SCOPE_SYSTEM, but not
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
function returns the contention scope attribute of the thread
attributes object referred to by
attr in the buffer pointed to
fail with the following errors:
An invalid value was specified in
scopespecified the value
PTHREAD_SCOPE_PROCESS, which is not supported on Linux.
For an explanation of the terms used in this section, see attributes(7).
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.
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