NAME

sched_rr_get_interval - get the SCHED_RR interval for the named process

SYNOPSIS

#include <sched.h>

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

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 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. The identified process should be running under the SCHED_RR scheduling policy.

The round robin time quantum value is not alterable under Linux 1.3.81.

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

RETURN VALUE

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

ERRORS

EFAULT

Problem with copying information to userspace.

EINVAL

Invalid pid.

ENOSYS

The system call is not yet implemented.

ESRCH

The process whose ID is pid could not be found.

CONFORMING TO

POSIX.1-2001.

BUGS

As of Linux 1.3.81 sched_rr_get_interval() returns with error ENOSYS, because SCHED_RR has not yet been fully implemented and tested properly.

SEE ALSO

sched_setscheduler(2) has a description of the Linux scheduling scheme.

Programming for the real world - POSIX.4 by Bill O. Gallmeister, O'Reilly & Associates, Inc., ISBN 1-56592-074-0