MagiCache: A Virtual In-Cache Computing Engine

The rise of data-parallel applications poses a significant challenge to the energy consumption of computing architectures.In-cache computation is a promising solution for achieving high parallelism and energy efficiency because it can eliminate data movement between the cache and the processor.Existing in-cache computing architectures transform a portion of cache arrays into computing arrays, with all rows of these arrays serving as computing lines.The remaining cache arrays are used as cachelines to store the data required by computing arrays or processors.However, in these array-level in-cache computing architectures, only a few computing lines in each computing array are active at runtime while the others are idle, which incurs severe cache capacity loss and space underutilization.In addition, bursty memory accesses of data-parallel applications also cause significant in-cache data movement latency.To address these problems, we propose MagiCache, a virtual in-cache computing engine.First, we design a novel cacheline-level in-cache computing architecture in which each cache array can configure some rows as computing lines and the other rows as cachelines with negligible overhead.Second, a virtual engine is further designed on this novel architecture to dynamically allocate different rows of each array as computing lines or cachelines based on runtime computation and storage requirements, thus realizing efficient cacheline-level space management.Finally, we present an instruction chaining technique to overlap the bursty access latency by enabling asynchronous execution of computing arrays.Evaluation results show that MagiCache achieves a 1.19x-1.61xspeedup over the state-of-the-art in-cache computing architectures with 6.5 KB of additional storage.Our cacheline-level space * These authors contributed equally to this work.