Decision Tree-Based Adaptive Reconfigurable Cache Scheme

Applications have different preferences for caches, sometimes even within the different running phases. Caches with fixed parameters may compromise the performance of a system. To solve this problem, we propose a real-time adaptive reconfigurable cache based on the decision tree algorithm, which can optimize the average memory access time of cache without modifying the cache coherent protocol. By monitoring the application running state, the cache associativity is periodically tuned to the optimal cache associativity, which is determined by the decision tree model. This paper implements the proposed decision tree-based adaptive reconfigurable cache in the GEM5 simulator and designs the key modules using Verilog HDL. The simulation results show that the proposed decision tree-based adaptive reconfigurable cache reduces the average memory access time compared with other adaptive algorithms.

ABOUT CACHE ASSOCIATIVITY IN LOW-COST SHARED MEMORY MULTI-MICROPROCESSORS

Sizes of on-chip caches on current commercial microprocessors range from 16 Kbytes to 36 Kbytes. These microprocessors can be directly used in the design of a low cost single-bus shared memory multiprocessors without using any second-level cache. In this paper, we explore the viability of such a multi-microprocessor. Simulations results clearly establish that performance of such a system will be quite poor if on-chip caches are direct-mapped. On the other hand, when the on-chip caches are partially associative, the achieved level of performance is quite promising. In particular, two recently proposed innovative cache structures, the skewed-associative cache organization and the semi-unified cache organization are shown to work fine.