Chun-Hung Wen

Design of multimedia storage systems for on-demand playback

This paper presents a comprehensive procedure to design multimedia storage systems for on-demand playback. The design stresses effective utilization of disk bandwidth with minimal data buffer to minimize overall system costs. The design procedure is most distinctive in the following two aspects: it bases on a tight upper bound of the lumped disk seek time for the Scan disk scheduling algorithm to achieve effective utilization of disk bandwidth; it starts with a general two-level hierarchical disk array structure to derive the optimal configuration for specific requirements.<<ETX>>

Designing a fully interactive video-on-demand server with a novel data placement and retrieval scheme

The paper discusses the design of a video-on-demand server that supports fully interactive operations such as play, fast forward search, and fast backward search, with a novel data placement and retrieval scheme. The main distinctions of this scheme are that (1) it requires neither extra disk bandwidth nor extra memory to support fast forward and fast backward searches; (2) it is based on a general two-level disk array architecture that exploits both parallelism and concurrency offered by fine-grain and coarse-grain disk array structures. >

Effective utilization of disk bandwidth for supporting interactive video-on-demand

This paper proposes a novel data retrieval scheme that achieves effective utilization of disk bandwidth for designing fully interactive video-on-demand systems. The main distinctions of the proposed data retrieval scheme are (1) it requires no extra disk bandwidth to support interactive features such as fast forward search and fast backward search; and (2) it is based on a data placement scheme that can effectively utilize disk bandwidth during normal-speed playback.

Design of a Video Storage System for Interactive Video-on-Demand

This paper discusses the design of a video-on-demand server that supports filly interactive operations such as play, fast forward search, and fast backward search, with a novel data placement and retrieval scheme. The main distinction of this scheme is that it is based on a general two-level disk array drchitecture that exploits both parallelism and concurrency offered by various levels of disk array structures. The proposed scheme requires no extra disk bandwidth to support interactive operations as many previously proposed schemes do. This nature, in turn, means more eflective utilimtion of disk bandwidth.

Conditional annulling for superscalar processors

This paper proposes an architectural feature for superscalar processors called conditional annulling. The conditional annulling mechanism achieves both the effects of conditional execution and speculative execution without incurring a significant increase of hardware complexity and cost. All effectiveness evaluation carried out in this paper shows the conditional annulling mechanism is effective in improving superscalar processor instruction scheduling.<<ETX>>

The effect of employing advanced branching mechanisms in superscalar processors

This paper discusses the effect of employing advanced branching mechanisms in superscalar processors. The motivation behind employing advanced branching mechanisms in superscalar processors is to reduce the control dependence, or in other words the number of branch operations, in the program so that instruction-level parallelism can be exploited more effectively. The second effect achieved by reducing the control dependence in the program is a decrease of the amount of branch penalty due to less branch operations. In this paper, two advanced branching mechanisms are discussed. The first mechanism involves incorporating multiple condition registers in superscalar processors. The second mechanism is a novel multi-way branching scheme proposed in this paper. A quantitative analysis on the effect of the two branching mechanisms shows that incorporating multiple condition registers can boost the superscalar processor performance by a factor of 16% to 20% while employing the proposed multi-way branching mechanism can achieve even greater performance improvement, up to 47%.

Storage hierarchy design in video-on-demand servers

This paper proposes a design procedure that exploits storage devices with different cost/bandwidth and cost/capacity ratios to build a hierarchical storage system for video-on- demand with minimum cost. The storage system is assumed to have two levels of hierarchy. The level-1 storage devices feature a low cost/bandwidth ratio and a high cost/capacity ratio. On the other hand, the level-2 storage devices feature a high cost/bandwidth ratio and a low cost/capacity ratio. The proposed procedure determines, with respect to overall system cost, which level of the hierarchy each program should be placed into. Based on the decisions, the designer then can figure out the appropriate configuration of the hierarchical storage system. The optimization target is to minimize the overall cost of the storage system.

Upgrading the service capacity of video-on-demand servers with memory buffer

In this paper, we propose a new approach to exploit semiconductor memory to upgrade the service capacity of video-on-demand systems. The basic idea behind this so-called Gneralized Relay Mechanism is that if we can relay the data of frequently accessed programmes from one access request to another, then we can improve the service capacity of the system without requiring higher disk bandwidth. The design of the Generalized Relay Mechanism is aimed at optimizing allocation and trade-off of the memory resource and the disk bandwidth resource. A simulation-based study shows that the Generalized Relay Mechanism is a very competitive alternative in comparision with simply incorporating more hard disks. If compared with an intuitive approach of utilizing memory buffer that always fills up the memory with most frequently accessed programmes, the Generalized Relay Mechanism enjoys an advantage in terms of cost.