This paper presents asymptotically equal lower and upper bounds for the number of parallel I/O operations required to perform bit-matrix-multiply/complement (BMMC) permutations on the Parallel Disk Model proposed by Vitter and Shriver. A BMMC permutation maps a source index to a target index by an affine transformation over GF (2), where the source and target indices are treated as bit vectors. The class of BMMC permutations includes many common permutations, such as matrix transposition (when dimensions are powers of 2), bit-reversal permutations, vector-reversal permutations, hypercube permutations, matrix reblocking, Graycode permutations, and inverse Gray-code permutations. The upper bound improves upon the asymptotic bound in the previous best known BMMC algorithm and upon the constant factor in the previous best known bit-permute/complement (BPC) permutation algorithm. The algorithm achieving the upper bound uses basic linear-algebra techniques to factor the characteristic matrix...

Although several algorithms have been developed for the Parallel Disk Model (PDM), few have beenimplemented. Consequently, little has been known about the accuracy of thePDMin measuring I/O time and total running time toperform an out-of-core computation. This paper analyzes timing results on multiple-disk platforms fortwo PDM algorithms, out-of-core radix sort and BMMC permutations, to determine the strengths and weaknesses of thePDM. The results indicate the following. First, good PDM algorithms are usually not I/O bound. Second, of the four PDM parameters, one (problem size) is a good indicator of I/O time and running time, one (memory size) is a good indicator of I/O time but not necessarily running time, and the other two (block size and number of disks) do not necessarily indicate either I/O or running time. Third, because PDM algorithms tendnottobeI/Obound, using asynchronous I/O can reduce I/O wait times signi cantly. The software interface to the PDM is part of the ViC * run-time library. The interface is a set of wrappers that are designed to be both e cient and portable across several underlying le systems and target machines. 1

a continuous media file server is presented to demonstrate the effectiveness of design decisions and to illuminate the impact of continuous media storage on computer architecture. To my family Preface I am grateful to my supervisor Professor Roger Needham for the opportunity and encouragement to pursue this research. My thanks and appreciation also go to numerous members of the Computer Laboratory. Particular members of the System Research Group deserve special mention including, Joe Dixon, Cosmos Nicolaou, Derek McAuley, Glenford Mapp, Cormac Sreenan, Eoin Hayden, Tim Wilson, Richard Black and Mark Hayter. Their valuable advice and constant stimulation provided an excellent environment in which to develop my understanding. For reading and commenting on earlier drafts of this dissertation, I thank Cormac Sreenan, Richard Black, Simon Crosby, Cosmos Nicolaou, Roger Needham, Tim Wilson, Heather Leitch, Mark Hayter and Derek McAuley. My deepest appreciation i

This paper was subsequently published in Operating Systems Review 25(1):56--59, Jan. 1991.

File systems and I/O subsystems should be smart ; they can analyze how they are being used and tune themselves dynamically to improve their performance. File systems should select caching and disk placement strategies on a per-file basis, and they should use system-wide disk reorganization strategies. For example, systems should be able to reorganize the data on disk automatically during idle periods so that system performance is improved during future periods of peak load. This dissertation presents the design and analysis of iPcress, a prototype of a nextgeneration file system. iPcress is a smart, high-performance, reliable file system. It uses statistical information collected on a per-file basis to tune itself. iPcress has a framework in which various optimizations can be performed by the file system automatically. It is extensible; other optimization techniques can be incorporated easily, so that the system may evolve. In addition, iPcress can incorporate a variety of file access...

this paper, we assume that all graphs are undirected, an assumption that may not hold for certain applications such as hypertext and object-oriented databases. One important assumption of our model is that data may be multiply represented in blocks. This is a stronger assumption than that used, for example, by external

Reducing the Cost of System Administration of a Disk Storage System Built from Commodity Components by Satoshi Asami Doctor of Philosophy in Computer Science University of California at Berkeley This dissertation explores how to reduce the system administration cost of disk storage systems. There are several reasons why reducing the operator's burden is the key to success of large storage systems. One is that the cost of system administration usually dominates the budget of storage systems. Another is that an operator error on storage systems can easily have disastrous results. In the field of physiology and psychology, there have been studies that show reducing mental and physical stress on the operator is crucial in preventing human errors.