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SCHED_RR_GET_INTERVAL(2) | Linux Programmer's Manual | SCHED_RR_GET_INTERVAL(2) |
NAME¶
sched_rr_get_interval - get the SCHED_RR interval for the named processSYNOPSIS¶
#include <sched.h>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.struct timespec { time_t tv_sec; /* seconds */ long tv_nsec; /* nanoseconds */ };
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 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.
CONFORMING TO¶
POSIX.1-2001.NOTES¶
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. Since Linux 2.6.24, the SCHED_RR quantum cannot be modified.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.COLOPHON¶
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.2011-10-16 | Linux |