Browsing by Author "Lee, PCH"

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Hipec: A system for application-customized virtual-memory caching management
(1997-05-01)
Lee, PCH
;
Chang, RC
;
Chen, MC
;
資訊工程學系
;
Department of Computer Science
Conventional operating systems employ a kernel-controlled caching strategy that cannot properly serve all access-pattern types used by applications. When running under these systems, many memory-intensive applications with mis-matching access patterns cause excessive page faults and page replacements that reduce the application's performance. This paper presents the hipec system, which allows applications to have their own caching strategies for managing page frames with negligible overhead. Since application designers know the access patterns of their applications, the specific caching strategies can be tuned to meet the needs of each application. Empirical results show that the hipec system significantly improves application performance and system throughput. (C) 1997 John Wiley & Sons, Ltd.
Managing flash memory in personal communication devices
(1997)
Chiang, ML
;
Lee, PCH
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
This paper describes a Flash Memory Server (FMS) for personal communication devices and embedded home information systems, such as set-top boxes and internet phones. Flash memory is small, lightweight, shock-resistant, nonvolatile, and requires little power. Writing to flash memory segments requires erasing the segment in advance. However, erase operations are slow and power-wasting that usually decrease system performance. The number of erase cycle is also limited. To reduce the number of erase operations needed and to evenly wear flash memory, a new flash memory management scheme has been designed. A new cleaning policy is also proposed to reduce cleaning overhead. Performance evaluations show that erase operations can be reduced by 55%.
Using data clustering to improve cleaning performance for flash memory
(1999-03-01)
Chiang, ML
;
Lee, PCH
;
Chang, RC
;
資訊工程學系
;
Department of Computer Science
Flash memory offers attractive features for storage of data, such as non-volatility, shock resistance, fast access speed, and low power consumption. However, it requires erasing before it can be overwritten. The erase operations are slow and consume comparatively a great deal of power, Furthermore, flash memory can only be Erased a limited number of times. To overcome hardware limitations, we use the non-in-place update mechanism that requires a cleaner to reclaim space occupied by obsolete data. To improve cleaning performance and prolong hash memory lifetime, we propose a new data reorganization method. By this method, data in flash memory are dynamically classified and clustered together according to their accessing frequencies, Experimental results show that this clustering technique significantly improved the cleaning performance for a variety of cleaning algorithms. The number of erase operations performed is greatly reduced and flash memory lifetime is prolonged. Even wearing is ensured as well, Copyright (C) 1999 John Wiley & Sons, Ltd.