uITRON supports only priority based pre-emptive scheduling. However, Round-Robin scheduling can be implemented by the application through assigning the tasks the same priority and calling rot_rdq periodically from cyclic handler etc.
QNX supports
FIFO Scheduling→Priority based pre-emptive
RoundRobin→Timeslice
Sporadic(spuraadic) scheduling→thread's priority oscillates dynamically between a foreground or normal priority and a background or low priority according to the execution time.This behavior is essential when Rate Monotonic Analysis (RMA) is being performed on a system that services both periodic and aperiodic events. Essentially, this algorithm allows a thread to service aperiodic events without jeopardizing the hard deadlines of other threads or processes in the system.
http://www.qnx.com/developers/docs/6.5.0/topic/com.qnx.doc.neutrino_sys_arch/kernel.html#SCHEDULING
See the below post for adaptive scheduling.
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Adaptive partition schedulers are a relatively new type of partition scheduler, pioneered with the most recent version of the QNX operating system. Adaptive partitioning, or AP, allows the real-time system designer to request that a percentage of processing resources be reserved for a particular partition (group of threads and/or processes making up a subsystem). The operating system's priority-driven pre-emptive scheduler will behave in the same way that a non-AP system would until the system is overloaded (i.e. system-wide there is more computation to perform than the processor is capable of sustaining over the long term). During overload, the AP scheduler enforces hard limits on total run-time for the subsystems within a partition, as dictated by the allocated percentage of processor bandwidth for the particular partition.
If the system is not overloaded, a partition that is allocated (for example) 10% of the processor bandwidth, can, in fact, use more than 10%, as it will borrow from the spare budget of other partitions (but will be required to pay it back later). This is very useful for the non real-time subsystems that experience variable load, since these subsystems can make use of spare budget from hard real-time partitions in order to make more forward progress than they would in a fixed partition scheduler such as ARINC-653, but without impacting the hard real-time subsystems' deadlines.
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QNX supports
FIFO Scheduling→Priority based pre-emptive
RoundRobin→Timeslice
Sporadic(spuraadic) scheduling→thread's priority oscillates dynamically between a foreground or normal priority and a background or low priority according to the execution time.This behavior is essential when Rate Monotonic Analysis (RMA) is being performed on a system that services both periodic and aperiodic events. Essentially, this algorithm allows a thread to service aperiodic events without jeopardizing the hard deadlines of other threads or processes in the system.
http://www.qnx.com/developers/docs/6.5.0/topic/com.qnx.doc.neutrino_sys_arch/kernel.html#SCHEDULING
See the below post for adaptive scheduling.
----
Adaptive partition schedulers are a relatively new type of partition scheduler, pioneered with the most recent version of the QNX operating system. Adaptive partitioning, or AP, allows the real-time system designer to request that a percentage of processing resources be reserved for a particular partition (group of threads and/or processes making up a subsystem). The operating system's priority-driven pre-emptive scheduler will behave in the same way that a non-AP system would until the system is overloaded (i.e. system-wide there is more computation to perform than the processor is capable of sustaining over the long term). During overload, the AP scheduler enforces hard limits on total run-time for the subsystems within a partition, as dictated by the allocated percentage of processor bandwidth for the particular partition.
If the system is not overloaded, a partition that is allocated (for example) 10% of the processor bandwidth, can, in fact, use more than 10%, as it will borrow from the spare budget of other partitions (but will be required to pay it back later). This is very useful for the non real-time subsystems that experience variable load, since these subsystems can make use of spare budget from hard real-time partitions in order to make more forward progress than they would in a fixed partition scheduler such as ARINC-653, but without impacting the hard real-time subsystems' deadlines.
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