Replacement Algorithms

The effect of caching is fully determined by the program locality or the data reuse and several cache management techniques try to base their decisions on the prediction of temporal locality in programs. However, prior work reports only rough techniques which either try to predict when a cache block loses its temporal locality or try to categorize cache items as highly or poorly temporal. In this work, we quantify the temporal characteristics of the cache block at run time by predicting the cache block reuse distances (measured in intervening cache accesses), based on the access patterns of the instructions (PCs) that touch the cache blocks. We show that an instruction-based reused distance predictor is very accurate and allows approximation of optimal replacement decisions, since we can "see" the future. We experimentally evaluate our prediction scheme in various sizes L2 caches using a subset of the most memory intensive SPEC2000 benchmarks. Our proposal obtains a significant improvement in terms of IPC over traditional LRU up to 130.6% (17.2% on average) and it also outperforms the previous state of the art proposal (namely Dynamic Insertion Policy or DIP) by up to 80.7% (15.8% on average).

Cloud computing systems use distributed file systems (DFSs) to store and process large data generated in the organizations. The users of the web-based information systems very frequently perform read operations and infrequently carry out write operations on the data stored in the DFS. Various caching and prefetching techniques are proposed in the literature to improve performance of the read operations carried out on the DFS. In this paper, we have proposed a novel speculative read algorithm for improving performance of the read operations carried out on the DFS by considering the presence of client-side and global caches in the DFS environment. The proposed algorithm performs speculative executions by reading the data from the local client-side cache, local collaborative cache, from global cache and global collaborative cache. One of the speculative executions will be selected based on the time stamp verification process. The proposed algorithm reduces the write/update overhead and hence performs better than that of the non-speculative algorithm proposed for the similar DFS environment.

The effect of caching is fully determined by the program locality or the data reuse and several cache management techniques try to base their decisions on the prediction of
temporal locality in programs. However, prior work reports only rough techniques which either try to predict when a cache block loses its temporal locality or try to categorize cache items as highly or poorly temporal. In this work, we quantify the temporal characteristics of the cache block at run time by predicting the cache block reuse distances (measured in intervening cache accesses), based on the access patterns of the instructions (PCs) that touch the cache blocks. We show that an instruction-based reused distance predictor is very accurate and allows approximation of optimal replacement decisions, since we can “see” the future. We experimentally evaluate our prediction scheme in various sizes L2 caches using a subset of the most memory intensive SPEC2000 benchmarks. Our proposal obtains a significant improvement in terms of IPC over traditional LRU up to 130.6% (17.2% on average) and it also outperforms the previous state of the art proposal (namely Dynamic Insertion Policy or DIP) by up to 80.7% (15.8% on average).