Performance Analysis and Evaluation of Ternary Optical Computer Based on Asynchronous Multiple Vacations

Ternary optical computer(TOC) has become a research hotspot in the field because of the advantages such as inherent parallelism, numerous trits, low power consumption, extendibility, bitwise allocability and dynamical bitwise reconfigurability. Meanwhile, its performance evaluation attracts more and more attentions from potential users and researchers. To model its computing ecology more accurately, this paper first builds a three-staged TOC service model by introducing asynchronous multi-vacations and tandem queueing, and then proposes a task scheduling algorithm and an optical processor allocation algorithm with asynchronous vacations of some small optical processors after dividing equally the entire optical processor into several small optical processors which can be used independently. At the same time, the analytical model was established to obtain important performance indicators such as response time, the number of tasks and utilization of optical processor, based on M/M/1 and M/M/n queuing system with asynchronous multi-vacations. In addition, relevant numerical simulation experiments are conducted. The results illustrate that the number of small optical processors, vacation rate and the number of small optical processors allowed to be on vacation have important effects on the system performance. Compared with synchronous vacation, asynchronous vacation not only ensures the system to obtain better maintenance but also improves the system performance to some degree.

An Efficient All Shapes Busy List Processor Allocation Algorithm for 3D Mesh Multicomputers

Contiguous processor allocation is useful for security and accounting reasons. This is due to the allocated jobs are separated from one another, where each sub-mesh of processors is allocated to an exclusive job request, and the allocated sub-mesh has the same size and shape of the requested job. The size and shape constraint leads to high processor fragmentation. Most recent contiguous allocation strategies suggested for 3D mesh-connected multiconputers try all possible orientations of an allocation request when allocation fails for the requested orientation, which reduces processor fragmentation and hence improves system performance. However, none of them considers all shapes of the request in the process of allocation. To generalize this restricted rotation, we propose, in this paper, a new contiguous allocation strategy for 3D mesh-connected multicomputers, referred to as All Shapes Busy List (ASBL for short), which takes into consideration all possible contiguous request shapes when attempting allocation for a job request. ASBL depends on the list of allocated sub-meshes, in the method suggested in (Bani-Mohammad et al., 2006), for selecting an allocated sub-mesh. The performance of the proposed ASBL allocation strategy has been evaluated considering several important scheduling strategies under a variety of system loads based on different job size distributions. The simulation results have shown that the ASBL allocation strategy improves system performance in terms of parameters such as the average turnaround time of jobs and system utilization under all scheduling strategies considered.