Leveraging bloom filters for smart search within NUCA caches

On-chip wire delays are becoming increasingly problematic in modern microprocessors. To alleviate the negative effect of wire delays, architects have considered splitting up large L2/L3 caches into several banks, with each bank having a different access latency depending on its physical proximity to the core. In particular, several recent papers have considered dynamic non-uniform cache architectures (D-NUCA) for chip multi-processors. These caches are dynamic in the sense that cache lines may migrate towards the cores that access them most frequently. In order to realize the benefits of data migration, however, a "smart search" mechanism for finding the location of a given cache line is necessary. These papers assume an oracle and leave the smart search for future work. Existing search mechanisms either entail high performance overheads or inordinate storage overheads. In this paper, we propose a smart search mechanism, based on Bloom filters. Our approach is complexity-effective: it has the potential to reduce the performance and storage overheads of D-NUCA implementations. Also, Bloom filters are simple structures that incur little design complexity. We present the results of our initial explorations, showing the promise of our novel search mechanism.