Dusty Caches to Save Memory Traffic

Reference counting is a garbage-collection technique that maintains a per-object count of the number of pointers to that object. When the count reaches zero, the object must be dead and can be collected. Although it is not an exact method, it is well suited for real-time systems and is widely implemented, sometimes in conjunction with other methods to increase the overall precision. A disadvantage of reference counting is the extra storage trac that is introduced. In this paper, we describe a new cache write-back policy that can substantially decrease the reference-counting traffic to RAM. We propose a new cache design that remembers the first-fetched value of a cache subblock, so that the subblock need not be written back to RAM unless a different value is present. We present results from experiments that show the effectiveness of this approach, particularly in mitigating the storage traffic due to reference counting