Abstract: An issue unit for placing a processor into a gradual slow down mode of operation is provided. The gradual slow down mode of operation comprises a plurality of stages of slow down operation of an issue unit in a processor in which the issuance of instructions is slowed in accordance with a staging scheme. The gradual slow down of the processor allows the processor to break out of livelock conditions. Moreover, since the slow down is gradual, the processor may flexibly avoid various degrees of livelock conditions. The mechanisms of the illustrative embodiments impact the overall processor performance based on the severity of the livelock condition by taking a small performance impact on less severe livelock conditions and only increasing the processor performance impact when the livelock condition is more severe.

Abstract: Mechanisms for placing a processor into a gradual slow down mode of operation are provided. The gradual slow down mode of operation comprises a plurality of stages of slow down operation of an issue unit in a processor in which the issuance of instructions is slowed in accordance with a staging scheme. The gradual slow down of the processor allows the processor to break out of livelock conditions. Moreover, since the slow down is gradual, the processor may flexibly avoid various degrees of livelock conditions. The mechanisms of the illustrative embodiments impact the overall processor performance based on the severity of the livelock condition by taking a small performance impact on less severe livelock conditions and only increasing the processor performance impact when the livelock condition is more severe.

Abstract: A method and system for enhancing processing efficiency in a data processing system which includes multiple scalar instruction processors and a vector instruction processor. An ordered sequence of intermixed scalar and vector instructions is processed in a nonsequential order by coupling those instructions to selected processors. As each instruction is finished an indication of that state is stored within a finish instruction array. The first vector instruction within the ordered sequence is initiated within the vector instruction processor only after an indication that each scalar instruction preceding the first vector instruction is finished. A vector advance signal is generated by the vector instruction processor each time processing of a vector instruction is initiated.