A Study on the Improvement of File System Performance

• Main Authors: Feng ,Li-Chi, 馮立琪
• Other Authors: Ruei-Chuan Chang
• Format: Others
• Language: en_US
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/04805421990543676070

博士 === 國立交通大學 === 資訊科學學系 === 84 === Due to the increasing gap between CPU and disk I/O speeds, file system is becoming the performance bottle-neck in computer system design. There are two types of entities in a file system: data and metadata. Data mean the actual contents of files. Metadata include access control and other descriptive about files. Previous research indicates that metadata writes account for 38-40% of disk I/O operations. We propose the design and implementation of a metadata ordering mechanism and its corresponding asynchronous write facility. With such a facility, we can eliminate large numbers of synchronous metadata writes, and have the flexibility of choosing a better way to these metadata modifications to disk asynchronously. Extensive performance evaluation shows that substantial performance improvement can be achieved under various benchmarks. Delayed write is a technique to improve the file system performance of UNIX operating systems. When write operations are delayed, an update policy decides how and when to write modified blocks to their assigned disk locations. Recent results show that conventional update mechanisms neglect the fact that different I/O requests naturally have different It makes time critical interactive jobs endure large variations response time. Update policy controls background write that are less time critical and should be performed under that do not violate the urgency of other time criti-cal jobs. In this thesis we also propose an effective update scheme. suggest new techniques : burst declustering and opportunistic asynchronous write. Besides, we develop a system activity sensor called SAPRO (system activity probe) that monitors the system activities and disk queuing status to adjust the behavior of our algorithm. Performance evaluation shows that our al-gorithm can alleviate the lengthy queuing delay, reduce the variance and case read response time significantly (40% and 90% The mean read response time and total system performance are also improved