sched_get_priority_max, sched_get_priority_min - get static priority range

#include <sched.h> int sched_get_priority_max(int policy); int sched_get_priority_min(int policy);

R sched_get_priority_max () returns the maximum priority value that can be used with the scheduling algorithm identified by policy. R sched_get_priority_min () returns the minimum priority value that can be used with the scheduling algorithm identified by policy. Supported policy values are R SCHED_FIFO , R SCHED_RR , R SCHED_OTHER , and R SCHED_BATCH . Further details about these policies can be found in sched_setscheduler(2). Processes with numerically higher priority values are scheduled before processes with numerically lower priority values. Thus, the value returned by R sched_get_priority_max () will be greater than the value returned by R sched_get_priority_min (). Linux allows the static priority value range 1 to 99 for SCHED_FIFO and SCHED_RR and the priority 0 for SCHED_OTHER and SCHED_BATCH. Scheduling priority ranges for the various policies are not alterable. The range of scheduling priorities may vary on other POSIX systems, thus it is a good idea for portable applications to use a virtual priority range and map it to the interval given by R sched_get_priority_max () and R sched_get_priority_min (). POSIX.1-2001 requires a spread of at least 32 between the maximum and the minimum values for SCHED_FIFO and SCHED_RR. POSIX systems on which R sched_get_priority_max () and R sched_get_priority_min () are available define _POSIX_PRIORITY_SCHEDULING in <unistd.h>.

On success, R sched_get_priority_max () and R sched_get_priority_min () return the maximum/minimum priority value for the named scheduling policy. On error, -1 is returned, and errno is set appropriately.

EINVAL

POSIX.1-2001.

sched_getaffinity(2), sched_getparam(2), sched_getscheduler(2), sched_setaffinity(2), sched_setparam(2), sched_setscheduler(2)

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