Performance Optimization of the Samba Read Service on Linux-based Network-Attached Storage Systems
Date Issued
2008
Date
2008
Author(s)
Wang, Chun-Wen
Abstract
In recent years, Network-Attached Storage (NAS) has become a popular choice for storing and sharing in a workgroup or at home. For low-end NAS servers, the tradeoffs between performance and cost is an important issue. Many low-end NAS servers failed to fully utilize the bandwidth of 1Gbps Ethernet network, because the processor embedded in those servers do not have sufficient computation power to process the network protocols and I/O operations. Several solutions were proposed: RDMA (Remote Direct Memory Access) supports zero-copy networking by enabling the network adapter to transfer data directly to or from application memory; TCP offload engine (TOE) shifts TCP/IP processing tasks to the network adapter or storage device. However, even with these solutions, hardware-software co-design is a key issue and software modifications are needed to take advantage from the offload engines. In this thesis, we present a study which uses performance evaluation tools and methodologies to guide software modifications and hardware-software co-design. In this case study, we evaluated the performance of read operations on a Samba server. Then, the performance was improved by porting the application into kernel space after identifying the performance bottleneck by tracing tools. Furthermore, we removed one unnecessary data copy operation for each read request. Our results showed that the performance was improved by 5.5% ~ 27.9% compared to original code. In addition, we compare the performance results with an existing method, the sendfile system call, which removes two major data copy operations while handling read requests in the Samba service.
Subjects
NAS
performance evaluation
performance optimization
zero-copy
Type
thesis
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