1SCHED_RR_GET_INTERVAL(2) Linux Programmer's Manual SCHED_RR_GET_INTERVAL(2)
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6 sched_rr_get_interval - get the SCHED_RR interval for the named process
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9 #include <sched.h>
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11 int sched_rr_get_interval(pid_t pid, struct timespec * tp);
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14 sched_rr_get_interval() writes into the timespec structure pointed to
15 by tp the round-robin time quantum for the process identified by pid.
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17 The timespec structure has the following form:
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19 struct timespec {
20 time_t tv_sec; /* seconds */
21 long tv_nsec; /* nanoseconds */
22 };
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24 If pid is zero, the time quantum for the calling process is written
25 into *tp. The identified process should be running under the SCHED_RR
26 scheduling policy. POSIX systems on which sched_rr_get_interval() is
27 available define _POSIX_PRIORITY_SCHEDULING in <unistd.h>.
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30 On success, sched_rr_get_interval() returns 0. On error, -1 is
31 returned, and errno is set appropriately.
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34 EFAULT Problem with copying information to userspace.
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36 EINVAL Invalid pid.
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38 ENOSYS The system call is not yet implemented (only on rather old ker‐
39 nels).
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41 ESRCH The process whose ID is pid could not be found.
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44 POSIX.1-2001.
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47 Linux Notes
48 POSIX does not specify any mechanism for controlling the size of the
49 round-robin time quantum. However, Linux provides a (nonportable)
50 method of doing this. The quantum can be controlled by adjusting the
51 process's nice value (see setpriority(2)). Assigning a negative (i.e.,
52 high) nice value results in a longer quantum; assigning a positive
53 (i.e., low) nice value results in a shorter quantum. The default quan‐
54 tum is 0.1 seconds; the degree to which changing the nice value affects
55 the quantum has varied somewhat across kernel versions.
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58 sched_setscheduler(2) has a description of the Linux scheduling scheme.
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60 Programming for the real world - POSIX.4 by Bill O. Gallmeister,
61 O'Reilly & Associates, Inc., ISBN 1-56592-074-0
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64 This page is part of release 3.25 of the Linux man-pages project. A
65 description of the project, and information about reporting bugs, can
66 be found at http://www.kernel.org/doc/man-pages/.
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70Linux 2007-04-06 SCHED_RR_GET_INTERVAL(2)