Process for dispatching tasks among multiple information processors

Abstract

In connection with an information processing network in which multiple processing devices have individual cache memories and also share a main storage memory, a process is disclosed for allocating multiple data operations or tasks for subsequent execution by the processing devices. A plurality of task dispatching elements (TDE) forming a task dispatching queue are scanned in an order of descending priority, for either a specific affinity to a selected one of the processing devices, or a general affinity to all of the processing devices. TDEs with specific affinity are assigned immediately if the selected processor is available, while TDEs of general affinity are reserved. TDEs with a specific affinity are bypassed if the selected processor is not available, or reserved if a predetermined bypass threshold has been reached. Following the primary scan a secondary scan, in an order of ascending priority, assigns any reserved tasks to the processing devices still available, without regard to processor affinity. Previously bypassed tasks can be assigned as well, in the event that any processor remains available. A further feature of the network is a means to reset the processor affinity of a selected task from the specific affinity to the general affinity. Resetting is accomplished through an assembly level instruction contained in the task, and either can be unconditional, with reset occurring whenever the task is executed on one of the processing devices, or can occur only upon the failure to meet a predetermined condition while the task is executing.