ASCache: An Approximate SSD Cache for Error-Tolerant Applications

With increased density, flash memory becomes more vulnerable to errors. Error correction incurs high overhead, which is sensitive in SSD cache. However, some applications like multimedia processing have the intrinsic tolerance of inaccuracies. In this paper, we propose ASCache, an approximate SSD cache, which allows bit errors in a controllable threshold for error-tolerant applications, so as to reduce the cache miss ratio caused by incorrect cache pages. ASCache further trades the strictness of error correction mechanisms for higher SSD access performance. Evaluations show ASCache reduces the average read latency by at most 30% and the cache miss ratio by 52%.