trong khi hình dung chương trình có thể được thực hiện trên một máy tính đơn giản cấp thấp. Cải tiến cơ bản so với phiên bản DEWIZ trước đó đã được thực hiện trong lĩnh vực hình dung chương trình. VISWIZ mô-đun tương ứng (được giới thiệu tại mục 4) cung cấp hoàn toàn được xác định sử dụng hình tượng hóa một cách rất dễ dàng. | 34 DISTRIBUTED AND PARALLEL SYSTEMS The main criteria for the algorithm and resource selection process in addition to the type of hardware and the programming paradigm used are given by the available number and speed of processors size of memory and the bandwidth between the involved hosts. Considering the size of the input data IS network bandwidth BW number of processors used NP available processor performance PP algorithm scalability AS problem size PS available memory size MS and the mapping factor MF which expresses the quality of the mapping between algorithm type and resource as shown in the table above the processing time for one step of the pipeline PT can be calculated as follows PT 1 BW NP pp AS MF MS v 7 The processing time is the sum of the data transmission time from the previous stage of the pipeline to the stage in question and the processing time on the grid node. These criteria not only include static properties but also highly dynamic ones like network or system load. For the mapping process the status of the dynamic aspects is retrieved during the resource information gathering phase. The algorithm properties relevant for the decision process are provided together with the according software modules and can looked up in the list of available software modules. Equation 1 only delivers a very rough estimation of the performance of a resource-algorithm combination. Therefore the result can only be interpreted as a relative quality measure and the processing time estimations PT for all possible resource-algorithm combinations have to be compared. Finally the combination yielding the lowest numerical result is selected. During the selection process the resource mapping for the pipeline stages is done following the expected dataflow direction. But this approach contains a possible drawback As the network connection bandwidth between two hosts is considered important a current resource mapping decision can also influence the resource mapping of the .
