Browsing by Author "Feng, LC"

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Achieving predictable response time with an intelligent file system updater
(1996-06-01)
Feng, LC
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Delayed write is a very popular 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 these modified blocks to their assigned disk locations. Recent research results show that conventional update mechanisms do not perform very well, because they neglect the fact that different I/O requests naturally have different characteristics. It makes time critical interactive jobs endure large variations in response time. Update policy controls background write activities that are less time critical and should be performed under constraints that do not violate the urgency of other time critical jobs. In this paper we propose an effective update scheme. We 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 algorithm can alleviate the lengthy queuing delay, reduce the variance and worst case read response time significantly (30% and 51% respectively). The mean read response time and total system performance are also improved.
Achieving predictable response time with an intelligent file system updater
(1996-06-01)
Feng, LC
;
Chang, RC
;
交大名義發表
;
資訊工程學系
;
National Chiao Tung University
Delayed write is a very popular 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 these modified blocks to their assigned disk locations. Recent research results show that conventional update mechanisms do not perform very well, because they neglect the fact that different I/O requests naturally have different characteristics. It makes time critical interactive jobs endure large variations in response time. Update policy controls background write activities that are less time critical and should be performed under constraints that do not violate the urgency of other time critical jobs. In this paper we propose an effective update scheme. We 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 algorithm can alleviate the lengthy queuing delay, reduce the variance and worst case read response time significantly (30% and 51% respectively). The mean read response time and total system performance are also improved.
Using asynchronous writes on metadata to improve file system performance
(1996-10-01)
Feng, LC
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Due to the increasing gap between CPU and disk I/O speeds, the file system is becoming the performance bottleneck in computer system design. How to improve file system performance is increasingly important. 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 information about files. Previous research indicates that metadata writes account for 38 - 40% of disk I/O operations. These large numbers of control request I/Os are usually ignored in traditional file system study, which concentrates only on file-level access patterns. We propose the design and implementation of a metadata-ordering mechanism and its corresponding asynchronous write facility. With such a facility, we can eliminate many synchronous metadata writes, and have the flexibility of choosing a better way to update these metadata modifications to disk asynchronously. Extensive performance evaluation shows that substantial performance improvement can be achieved under various benchmarks. Some other tests are also used to demonstrate the benefits and behaviors of this approach.
Using asynchronous writes on metadata to improve file system performance
(1996-10-01)
Feng, LC
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Due to the increasing gap between CPU and disk I/O speeds, the file system is becoming the performance bottleneck in computer system design. How to improve file system performance is increasingly important. 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 information about files. Previous research indicates that metadata writes account for 38 - 40% of disk I/O operations. These large numbers of control request I/Os are usually ignored in traditional file system study, which concentrates only on file-level access patterns. We propose the design and implementation of a metadata-ordering mechanism and its corresponding asynchronous write facility. With such a facility, we can eliminate many synchronous metadata writes, and have the flexibility of choosing a better way to update these metadata modifications to disk asynchronously. Extensive performance evaluation shows that substantial performance improvement can be achieved under various benchmarks. Some other tests are also used to demonstrate the benefits and behaviors of this approach.