Set-associative cache simulation using generalized binomial trees

Abstract

Set-associative caches are widely used in CPU memory hierarchies, I/O subsystems, and file systems to reduce average access times. This article proposes an efficient simulation technique for simulating a group of set-associative caches in a single pass through the address trace, where all caches have the same line size but varying associativities and varying number of sets. The article also introduces a generalization of the ordinary binomial tree and presents a representation of caches in this class using the Generalized Binomial Tree (gbt). The tree representation permits efficient search and update of the caches. Theoretically, the new algorithm, GBF_LS, based on the gbt structure, always takes fewer comparisons than the two earlier algorithms for the same class of caches: all-associativity and generalized forest simulation. Experimentally, the new algorithm shows performance gains in the range of 1.2 to 3.8 over the earlier algorithms on address traces of the SPEC benchmarks. A related algorithm for simulating multiple alternative direct-mapped caches with fixed cache size, but varying line size, is also presented.