HP-UX Reference (11i v1 00/12) - 2 System Calls (vol 5)

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rtsched(2) rtsched(2)

For this policy, valid priorities are within the range returned by the functions

sched_get_priority_max() and sched_get_priority_min() when

SCHED_RR is provided as the parameter. The priority range for this policy contains

at least 32 priorities.

SCHED_RR2 Round-robin scheduling policy, with a per-priority time slice (time quantum).

This policy is identical to the SCHED_RR policy, except that the round-robin time slice

interval returned by sched_rr_get_interval() depends upon the priority of

the speciﬁed process.

For this policy, valid priorities are within the range returned by the functions

sched_get_priority_max() and sched_get_priority_min() when

SCHED_RR is provided as the parameter. The priority range for this policy contains

at least 32 priorities.

SCHED_RTPRIO

Real-time scheduling policy with nondecaying priorities (like SCHED_FIFO and

SCHED_RR) with a priority range between the POSIX real-time policies and the HP-

UX policies, described below (see rtprio(2)).

For processes executing under this policy, the implementation must use only priorities

within the range returned by the functions sched_get_priority_max()

and

sched_get_priority_min()

when SCHED_RTPRIO is provided as the param-

eter. Note that, for the

SCHED_RTPRIO scheduling policy, smaller numbers

represent higher (stronger) priorities, which is the opposite of the POSIX scheduling

policies. This is done to provide continuing support for existing applications that

depend on this priority ordering. However, it is guaranteed that the priority range for

the SCHED_OTHER scheduling policy is properly disjoint from the priority ranges of

all of the other scheduling policies described and the strongest priority in the priority

range for SCHED_RTPRIO is weaker than the weakest priority in the priority ranges

for any of the POSIX policies, SCHED_FIFO , SCHED_RR, and SCHED_RR2.

SCHED_OTHER (SCHED_HPUX, SCHED_TIMESHARE

)

Another scheduling policy.

The

SCHED_OTHER policy, also known as SCHED_HPUX and SCHED_TIMESHARE

provides a way for applicationsto indicate, in a portable way, that they no longer need

a real-time scheduling policy.

For processes executing under this policy, the implementation can use only priorities

within the range returned by the functions

sched_get_priority_max()

and

sched_get_priority_min()

when SCHED_OTHER is provided as the parame-

ter. Note that for the

SCHED_OTHER scheduling policy, like SCHED_RTPRIO ,

smaller numbers represent higher (stronger) priorities, which is the opposite of the

POSIX scheduling policies. This is done to provide continuing support for existing

applicationsthat depend on this priority ordering. However, it is guaranteed that the

priority range for the SCHED_OTHER scheduling policy is properly disjoint from the

priority ranges of all of the real-time scheduling policies described and the strongest

priority in the priority range for SCHED_OTHER is weaker than the weakest priority

in the priority ranges for any of the other policies, SCHED_FIFO, SCHED_RR, and

SCHED_RR2.

SCHED_NOAGE

A timeshare scheduling policy with nondecaying priorities.

For processes executing under this policy, the implementation can use only priorities

within the range returned by the functions sched_get_priority_max() and

sched_get_priority_min() when SCHED_NOAGE is provided as the parame-

ter. The priority range for the SCHED_NOAGE policy is a subset of the priority range

supported by the SCHED_TIMESHARE policy. Note that for the SCHED_NOAGE

scheduling policy, smaller numbers represent higher (stronger) priorities, which is the

opposite of the POSIX scheduling policies.

The priority value of a process executing with the SCHED_NOAGE policy is not

decayed or boosted by the operating system scheduler. For SCHED_TIMESHARE

pol-

icy, the priority value of the process is decayed as the process consumes processor

cycles and boosted when the process waits for processor cycles.

HP-UX Release 11i: December 2000 − 5 − Section 2−−269

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