GNU/Linux man pages
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GNU/Linux |
RedHat 6.2(Zoot) |
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pthread_attr_setscope(3thr) |
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pthread_attr_init, pthread_attr_destroy, pthread_attr_setdetachstate, pthread_attr_getdetachstate, pthread_attr_setschedparam, pthread_attr_getschedparam, pthread_attr_setschedpolicy, pthread_attr_getschedpolicy, pthread_attr_setinheritsched, pthread_attr_getinheritsched, pthread_attr_setscope, pthread_attr_getscope − thread creation attributes
#include <pthread.h>
int pthread_attr_init(pthread_attr_t *attr);
int pthread_attr_destroy(pthread_attr_t *attr);
int pthread_attr_setdetachstate(pthread_attr_t *attr, int detachstate);
int pthread_attr_getdetachstate(const pthread_attr_t *attr, int *detachstate);
int pthread_attr_setschedpolicy(pthread_attr_t *attr, int policy);
int pthread_attr_getschedpolicy(const pthread_attr_t *attr, int *policy);
int pthread_attr_setschedparam(pthread_attr_t *attr, const struct sched_param *param);
int pthread_attr_getschedparam(const pthread_attr_t *attr, struct sched_param *param);
int pthread_attr_setinheritsched(pthread_attr_t *attr, int inherit);
int pthread_attr_getinheritsched(const pthread_attr_t *attr, int *inherit);
int pthread_attr_setscope(pthread_attr_t *attr, int scope);
int pthread_attr_getscope(const pthread_attr_t *attr, int *scope);
Setting attributes for threads is achieved by filling a thread attribute object attr of type pthread_attr_t, then passing it as second argument to pthread_create(3). Passing NULL is equivalent to passing a thread attribute object with all attributes set to their default values.
pthread_attr_init initializes the thread attribute object attr and fills it with default values for the attributes. (The default values are listed below for each attribute.)
Each attribute attrname (see below for a list of all attributes) can be individually set using the function pthread_attr_setattrname and retrieved using the function pthread_attr_getattrname.
pthread_attr_destroy destroys a thread attribute object, which must not be reused until it is reinitialized. pthread_attr_destroy does nothing in the LinuxThreads implementation.
Attribute objects are consulted only when creating a new thread. The same attribute object can be used for creating several threads. Modifying an attribute object after a call to pthread_create does not change the attributes of the thread previously created.
The following thread attributes are supported:
detachstate
Control whether the thread is created in the joinable state
(value PTHREAD_CREATE_JOINABLE) or in the detached
state ( PTHREAD_CREATE_DETACHED).
Default value: PTHREAD_CREATE_JOINABLE.
In the joinable state, another thread can synchronize on the thread termination and recover its termination code using pthread_join(3), but some of the thread resources are kept allocated after the thread terminates, and reclaimed only when another thread performs pthread_join(3) on that thread.
In the detached state, the thread resources are immediately freed when it terminates, but pthread_join(3) cannot be used to synchronize on the thread termination.
A thread created in the joinable state can later be put in the detached thread using pthread_detach(3).
schedpolicy
Select the scheduling policy for the thread: one of
SCHED_OTHER (regular, non-realtime scheduling),
SCHED_RR (realtime, round-robin) or SCHED_FIFO
(realtime, first-in first-out). See
sched_setpolicy(2) for more information on scheduling
policies.
Default value: SCHED_OTHER.
The realtime scheduling policies SCHED_RR and SCHED_FIFO are available only to processes with superuser privileges.
The scheduling policy of a thread can be changed after creation with pthread_setschedparam(3).
schedparam
Contain the scheduling parameters (essentially, the
scheduling priority) for the thread. See
sched_setparam(2) for more information on scheduling
parameters.
Default value: priority is 0.
This attribute is not significant if the scheduling policy is SCHED_OTHER; it only matters for the realtime policies SCHED_RR and SCHED_FIFO.
The scheduling priority of a thread can be changed after creation with pthread_setschedparam(3).
inheritsched
Indicate whether the scheduling policy and scheduling
parameters for the newly created thread are determined by
the values of the schedpolicy and schedparam
attributes (value PTHREAD_EXPLICIT_SCHED) or are
inherited from the parent thread (value
PTHREAD_INHERIT_SCHED).
Default value: PTHREAD_EXPLICIT_SCHED.
scope
Define the scheduling contention scope for the created
thread. The only value supported in the LinuxThreads
implementation is PTHREAD_SCOPE_SYSTEM, meaning that
the threads contend for CPU time with all processes running
on the machine. In particular, thread priorities are
interpreted relative to the priorities of all other
processes on the machine. The other value specified by the
standard, PTHREAD_SCOPE_PROCESS, means that
scheduling contention occurs only between the threads of the
running process: thread priorities are interpreted relative
to the priorities of the other threads of the process,
regardless of the priorities of other processes.
PTHREAD_SCOPE_PROCESS is not supported in
LinuxThreads.
Default value: PTHREAD_SCOPE_SYSTEM.
All functions return 0 on success and a non-zero error code on error. On success, the pthread_attr_getattrname functions also store the current value of the attribute attrname in the location pointed to by their second argument.
The pthread_attr_setdetachstate function returns the following error codes on error:
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EINVAL |
the specified detachstate is not one of PTHREAD_CREATE_JOINABLE or PTHREAD_CREATE_DETACHED. |
The pthread_attr_setschedparam function returns the following error codes on error:
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EINVAL |
the priority specified in param is outside the range of allowed priorities for the scheduling policy currently in attr (1 to 99 for SCHED_FIFO and SCHED_RR; 0 for SCHED_OTHER). |
The pthread_attr_setschedpolicy function returns the following error codes on error:
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EINVAL |
the specified policy is not one of SCHED_OTHER, SCHED_FIFO, or SCHED_RR. |
ENOTSUP
policy is SCHED_FIFO or SCHED_RR, and the effective user of the calling process is not super-user.
The pthread_attr_setinheritsched function returns the following error codes on error:
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EINVAL |
the specified inherit is not one of PTHREAD_INHERIT_SCHED or PTHREAD_EXPLICIT_SCHED. |
The pthread_attr_setscope function returns the following error codes on error:
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EINVAL |
the specified scope is not one of PTHREAD_SCOPE_SYSTEM or PTHREAD_SCOPE_PROCESS. |
ENOTSUP
the specified scope is PTHREAD_SCOPE_PROCESS (not supported).
Xavier Leroy <Xavier.Leroy@inria.fr>
pthread_create(3), pthread_join(3), pthread_detach(3), pthread_setschedparam(3).
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pthread_attr_setscope(3thr) | |