Originální popis anglicky:
pthread_getschedparam, pthread_setschedparam - dynamic thread scheduling
parameters access (
REALTIME THREADS)
Návod, kniha: POSIX Programmer's Manual
#include <pthread.h>
int pthread_getschedparam(pthread_t
thread, int
*restrict policy,
struct sched_param *restrict
param);
int pthread_setschedparam(pthread_t
thread, int
policy,
const struct sched_param *
param);
The
pthread_getschedparam() and
pthread_setschedparam() functions
shall, respectively, get and set the scheduling policy and parameters of
individual threads within a multi-threaded process to be retrieved and set.
For SCHED_FIFO and SCHED_RR, the only required member of the
sched_param structure is the priority
sched_priority. For
SCHED_OTHER, the affected scheduling parameters are implementation-defined.
The
pthread_getschedparam() function shall retrieve the scheduling policy
and scheduling parameters for the thread whose thread ID is given by
thread and shall store those values in
policy and
param,
respectively. The priority value returned from
pthread_getschedparam()
shall be the value specified by the most recent
pthread_setschedparam(),
pthread_setschedprio(), or
pthread_create() call affecting the target thread. It shall not reflect
any temporary adjustments to its priority as a result of any priority
inheritance or ceiling functions. The
pthread_setschedparam() function
shall set the scheduling policy and associated scheduling parameters for the
thread whose thread ID is given by
thread to the policy and associated
parameters provided in
policy and
param, respectively.
The
policy parameter may have the value SCHED_OTHER, SCHED_FIFO, or
SCHED_RR. The scheduling parameters for the SCHED_OTHER policy are
implementation-defined. The SCHED_FIFO and SCHED_RR policies shall have a
single scheduling parameter,
priority.
If _POSIX_THREAD_SPORADIC_SERVER is defined, then the
policy argument may
have the value SCHED_SPORADIC, with the exception for the
pthread_setschedparam() function that if the scheduling policy was not
SCHED_SPORADIC at the time of the call, it is implementation-defined whether
the function is supported; in other words, the implementation need not allow
the application to dynamically change the scheduling policy to SCHED_SPORADIC.
The sporadic server scheduling policy has the associated parameters
sched_ss_low_priority,
sched_ss_repl_period,
sched_ss_init_budget,
sched_priority, and
sched_ss_max_repl. The specified
sched_ss_repl_period shall be
greater than or equal to the specified
sched_ss_init_budget for the
function to succeed; if it is not, then the function shall fail. The value of
sched_ss_max_repl shall be within the inclusive range [1,
{SS_REPL_MAX}] for the function to succeed; if not, the function shall fail.
If the
pthread_setschedparam() function fails, the scheduling parameters
shall not be changed for the target thread.
If successful, the
pthread_getschedparam() and
pthread_setschedparam() functions shall return zero; otherwise, an
error number shall be returned to indicate the error.
The
pthread_getschedparam() function may fail if:
- ESRCH
- The value specified by thread does not refer to an
existing thread.
The
pthread_setschedparam() function may fail if:
- EINVAL
- The value specified by policy or one of the
scheduling parameters associated with the scheduling policy policy
is invalid.
- ENOTSUP
- An attempt was made to set the policy or scheduling
parameters to an unsupported value.
- ENOTSUP
- An attempt was made to dynamically change the scheduling
policy to SCHED_SPORADIC, and the implementation does not support this
change.
- EPERM
- The caller does not have the appropriate permission to set
either the scheduling parameters or the scheduling policy of the specified
thread.
- EPERM
- The implementation does not allow the application to modify
one of the parameters to the value specified.
- ESRCH
- The value specified by thread does not refer to a
existing thread.
These functions shall not return an error code of [EINTR].
The following sections are informative.
None.
None.
None.
None.
pthread_setschedprio() ,
sched_getparam() ,
sched_getscheduler() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<pthread.h>,
<sched.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
