PCStream: Automatic Stream Allocation Using Program Contexts

We propose a fully automatic stream management technique, called PCStream, for multi-streamed SSDs. PCStream is based on our observation that data lifetimes can be reliably predicted using write program contexts. By extracting program contexts during runtime, PCStream automates the data-to-stream mapping. When data mapped to the same stream show large differences in their lifetimes, PCStream moves the long-lived data of the current stream to its substream during garbage collection. Our experimental results show that PCStream can reduce the garbage collection overhead as much as a highly-optimized manual stream management technique while no code modification is necessary.