доступ к параметрам динамического планирования потоков (REALTIME THREADS) (dynamic thread scheduling parameters access (REALTIME THREADS))
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
pthread_getschedparam, pthread_setschedparam — dynamic thread
scheduling parameters access (REALTIME THREADS)
Синопсис (Synopsis)
#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);
Описание (Description)
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. It is unspecified whether the
sched_ss_repl_period and sched_ss_init_budget values are stored
as provided by this function or are rounded to align with the
resolution of the clock being used.
If the pthread_setschedparam() function fails, the scheduling
parameters shall not be changed for the target thread.
Возвращаемое значение (Return value)
If successful, the pthread_getschedparam() and
pthread_setschedparam() functions shall return zero; otherwise,
an error number shall be returned to indicate the error.
Ошибки (Error)
The pthread_setschedparam() function shall fail if:
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.
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.
EPERM The caller does not have appropriate privileges 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.
These functions shall not return an error code of [EINTR].
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
If an implementation detects use of a thread ID after the end of
its lifetime, it is recommended that the function should fail and
report an [ESRCH] error.
Будущие направления (Future directions)
None.
Смотри также (See also)
pthread_setschedprio(3p), sched_getparam(3p),
sched_getscheduler(3p)
The Base Definitions volume of POSIX.1‐2017, pthread.h(0p),
sched.h(0p)
