CostFM: A High Cost-Performance Fingerprint Management Mechanism for Shared SSDs
Hao Liu, Mengting Lu, Fang Wang, Wenpeng He · 2023
As the storage and I/O demand of contemporary computer systems grow, SSDs with deduplication are widely deployed as shared storage devices to provide high performance in cloud platforms where diverse tenant workloads are collocated. However, existing global and fixed fingerprint management schemes are inefficient in the multi-tenant environment. Contention for in-memory fingerprint cache, embedded in DRAM to speed up fingerprint lookups, results in decreased cache utilization, and abundant fingerprint lookups into the backend flash memory degrade the system performance. Besides, a fixed cache replacement policy for all the tenants fails to capture the diverse characteristics, further increasing the lookup overhead.This paper introduces CostFM, a novel fingerprint management mechanism highlighted by two notable features. First, it provides a benefit-aware cache allocation scheme, which estimates the cache hit gains of each tenant and uses dynamic programming to find the optimal cache allocation scheme, avoiding the cache contention for the fingerprint resource and improving cache utilization. Second, it applies a user-based policy model that captures access characteristics to select the suitable cache management policy for each tenant, boosting overall cache efficiency. Extensive experimental results show that CostFM decreases the average request latency by up to 30%, and it also reduces the fingerprint writes into the flash memory by up to 4.7x.