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   sched_rr_get_interval    ( 2 )

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Имя (Name)

sched_rr_get_interval - get the SCHED_RR interval for the named
       process

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Синопсис (Synopsis)

#include <sched.h>

       int sched_rr_get_interval(pid_t pid, struct timespec *tp);

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Описание (Description)

sched_rr_get_interval() writes into the timespec structure
       pointed to by tp the round-robin time quantum for the process
       identified by pid.  The specified process should be running under
       the SCHED_RR scheduling policy.

       The timespec structure has the following form:

           struct timespec {
               time_t tv_sec;    /* seconds */
               long   tv_nsec;   /* nanoseconds */
           };

       If pid is zero, the time quantum for the calling process is
       written into *tp.

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Возвращаемое значение (Return value)

On success, sched_rr_get_interval() returns 0.  On error, -1 is
       returned, and errno is set to indicate the error.

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Ошибки (Error)

EFAULT Problem with copying information to user space.

       EINVAL Invalid pid.

       ENOSYS The system call is not yet implemented (only on rather old
              kernels).

       ESRCH  Could not find a process with the ID pid.

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Стандарты (Conforming to)

POSIX.1-2001, POSIX.1-2008.

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Примечание (Note)

POSIX systems on which sched_rr_get_interval() is available
       define _POSIX_PRIORITY_SCHEDULING in <unistd.h>.

   Linux notes
       POSIX does not specify any mechanism for controlling the size of
       the round-robin time quantum.  Older Linux kernels provide a
       (nonportable) method of doing this.  The quantum can be
       controlled by adjusting the process's nice value (see
       setpriority(2)).  Assigning a negative (i.e., high) nice value
       results in a longer quantum; assigning a positive (i.e., low)
       nice value results in a shorter quantum.  The default quantum is
       0.1 seconds; the degree to which changing the nice value affects
       the quantum has varied somewhat across kernel versions.  This
       method of adjusting the quantum was removed starting with Linux
       2.6.24.

       Linux 3.9 added a new mechanism for adjusting (and viewing) the
       SCHED_RR quantum: the /proc/sys/kernel/sched_rr_timeslice_ms file
       exposes the quantum as a millisecond value, whose default is 100.
       Writing 0 to this file resets the quantum to the default value.

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Смотри также (See also)

sched(7)

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