Accelerating Garbage Collection of 3D Flash Memory via Exploiting Inter-Channel Parallelism

3D flash memory relaxes the scaling constraints but unfortunately arouses the tedious garbage collection (GC) problem. We identify via an in-depth analysis that the root cause is the intra-channel relocation in conventional GC operations. We present ParaGC, an approach that strives to speed up the GC process via fully exploiting the inter-channel parallelism of 3D flash memory. ParaGC builds on two elementary designs: (i) relocation arrangement, which carefully determines the relocation traffic that each channel affords; and (ii) page assignment, which dispatches pages based on the access characteristic and the channel busyness. We implement ParaGC and conduct extensive experiments with ten real-world traces, showing that ParaGC can reduce 20.2-41.3% of the read latency, 24.3-38.8% of the write latency, and 51.5-75.8% of the GC latency.