A Method for Eliminating Metadata Cache Deallocation Latency in Enterprise File Servers

This paper presents an analysis of a performance bottleneck in enterprise file servers using Linux and proposes a modification to this operation system for avoiding the bottleneck. The analysis shows that metadata cache deallocation of current Linux causes large latency in file-request processing when the operational throughput of a file server becomes large. To eliminate the latency caused by metadata cache deallocation, a new method, called “split reclaim,” which divides metadata cache deallocation from conventional cache deallocation, is proposed. It is experimentally shown that the split-reclaim method reduces the worst response time by more than 95% and achieves three times higher throughput under a metadata-intensive workload. The split-reclaim method also reduces latency caused by cache deallocation under a general file-server workload by more than 99%. These results indicate that the split-reclaim method can eliminate metadata cache deallocation latency and make possible the use of commodity servers as enterprise file servers.