1SCHED_GET_PRIORITY_MAX(2)  Linux Programmer's Manual SCHED_GET_PRIORITY_MAX(2)
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NAME

6       sched_get_priority_max,  sched_get_priority_min   - get static priority
7       range
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SYNOPSIS

10       #include <sched.h>
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12       int sched_get_priority_max(int policy);
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14       int sched_get_priority_min(int policy);
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DESCRIPTION

17       sched_get_priority_max() returns the maximum priority value that can be
18       used    with   the   scheduling   algorithm   identified   by   policy.
19       sched_get_priority_min() returns the minimum priority value that can be
20       used  with  the  scheduling  algorithm identified by policy.  Supported
21       policy  values  are  SCHED_FIFO,  SCHED_RR,  SCHED_OTHER,  SCHED_BATCH,
22       SCHED_IDLE,  and  SCHED_DEADLINE.  Further details about these policies
23       can be found in sched(7).
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25       Processes with numerically higher priority values are scheduled  before
26       processes  with  numerically  lower  priority  values.  Thus, the value
27       returned by sched_get_priority_max() will be  greater  than  the  value
28       returned by sched_get_priority_min().
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30       Linux  allows  the static priority range 1 to 99 for the SCHED_FIFO and
31       SCHED_RR policies, and the  priority  0  for  the  remaining  policies.
32       Scheduling priority ranges for the various policies are not alterable.
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34       The  range  of  scheduling  priorities may vary on other POSIX systems,
35       thus it is a good idea for portable applications to use a virtual  pri‐
36       ority  range  and  map  it  to  the  interval given by sched_get_prior‐
37       ity_max() and sched_get_priority_min POSIX.1 requires a  spread  of  at
38       least  32 between the maximum and the minimum values for SCHED_FIFO and
39       SCHED_RR.
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41       POSIX systems on which  sched_get_priority_max()  and  sched_get_prior‐
42       ity_min()    are   available   define   _POSIX_PRIORITY_SCHEDULING   in
43       <unistd.h>.
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RETURN VALUE

46       On  success,  sched_get_priority_max()   and   sched_get_priority_min()
47       return the maximum/minimum priority value for the named scheduling pol‐
48       icy.  On error, -1 is returned, and errno is set appropriately.
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ERRORS

51       EINVAL The argument policy does not identify a defined scheduling  pol‐
52              icy.
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CONFORMING TO

55       POSIX.1-2001, POSIX.1-2008.
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SEE ALSO

58       sched_getaffinity(2), sched_getparam(2), sched_getscheduler(2),
59       sched_setaffinity(2), sched_setparam(2), sched_setscheduler(2),
60       sched(7)
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COLOPHON

63       This page is part of release 5.02 of the Linux man-pages project.  A
64       description of the project, information about reporting bugs, and the
65       latest version of this page, can be found at
66       https://www.kernel.org/doc/man-pages/.
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70Linux                             2017-09-15         SCHED_GET_PRIORITY_MAX(2)
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