Data processing system having tunable operating system means

A multiprogrammed computer system in which a plurality of tasks are executing concurrently, each task having an associated dispatch priority value signal, said computer providing

• a central processor,
• monitor and keyboard means connected to said central processor, and providing a designated key,
• said concurrently executing tasks including a specific task associated with said monitor and keyboard means,
• timing means for awaiting completion of a time interval,
• queue storage means for representing a plurality N of ready queues comprising representations of tasks queued for control of said central processor, each queue having a queue priority associated with its position, said queue priorities together with the positions of the task representations within said queues identifying a next task,
• dispatching means responsive to said queue storage means for giving said next task control of said central processor, and for setting said timing means,
• operating system means responsive to said central processor and to said timing means for detecting when a dispatched task has controlled said central processor for a time period at least equal to said time interval and for associating with such task a worsened dispatch priority value,
• queue subset limit means for providing signals defining, for each said concurrent task, a subset of M ready queues,
• said computer further providing scheduler means responsive, for each task awaiting control of said central processor, to its said associated dispatch priority value signal and to said queue subset limit signals for placing a representation of said task in a particular ready queue within said ready queue subset defined for said task,
• said scheduler means being responsive to actuation of said designated key to reset said dispatch priority value signal associated with said specific task such that said specific task is placed in a said ready queue in an upper half of said specific task ready queue subset.

A multiprogrammed computer in which a plurality of concurrently executing tasks share use of a central processor, each task being associated with a task class, said computer including

• timing means for measuring duration of servicing a task by said central processor,
• inter-task message facility means for communicating among said concurrently executing tasks,
• ready queue storage means for storing a representation of a plurality of ready queues having priorities ranked as to better or worse for obtaining service from said central processor, said ready queue priorities together with positions of tasks in said ready queues defining a next task for receiving service from said central processor,
• dispatcher means for initiating service from said central processor for said next defined task when said central processor is available,
• interrupt means for suspending servicing of a task by the central processor after service for a service time limit defined prior to start of servicing,
• range limit storage means for defining for each said task class an assignable range of ready queue priorities to which tasks of an associated class may be assigned, the assignable range including a best priority and a worst priority ready queue assignable for each task class, the assignable ranges being defined such that each is unique and such that there is at least one ready queue common to all assignable ranges,
• a dispatch signal storage means associated with each task for indicating the ready queue to which the task was last assigned,
• scheduler means for assigning to ready queues tasks requiring service from said central processor, said scheduler means
• assigning a particular task to a ready queue with a worse priority than that to which said particular task was last assigned when said particular task is suspended from its control of the central processor by expiration of its defined service time limit,
• assigning a particular task to a ready queue with a better priority than that to which said particular task was last assigned when said particular task is suspended from its control of said central processor by requesting service by said inter-task message facility means,
• ready queues to which a task is assigned by said scheduler means being, however, restricted to the assignable range of ready queues associated with the particular task.