Abstract-In this paper, we propose the use of feedback control schemes in multiprocessor systems. In a multiprocessor, individual processors do not have complete control over, nor information about, the overall state of the system. The potential exists, then, for the processors to unknowingly interact in such a way as to degrade the performance of the system. An example of this is the problem of tree saturation caused by hot spot accesses in multiprocessors using multistage interconnection networks. Tree saturation degrades the performance of all processors in the system, including those not participating in the hot spot activity. We see that feedback schemes can be used to control tree saturation, reducing degradation to memory requests that are not to the hot spot, and thereby increasing overall system performance. As a companion to feedback schemes, damping schemes are also considered. Simulation studies presented in this paper show that feedback schemes can improve overall system performance significantly in many cases and with relatively little hardware cost. Damping schemes in conjunction with feedback are shown to further improve system performance.
Scott and Sohi describe the use of explicit feedback to inform nodes when tree-saturation is imminent in multistage interconnection networks REF .
The use of feedback in multiprocessors and its application to tree saturation control
IEEE Trans. Parallel Distrib. Syst.
IEEE Trans. Parallel Distrib. Syst.
Computer Science