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DISTRIBUTED AND PARALLEL SYSTEMSCLUSTER AND GRID COMPUTING 2005 phần 7

và được nối lại dưới một hồ bơi Condor không thân thiện sau khi nộp lại. Cơ chế checkpointing tự động (không tương tác người dùng) có thể hỗ trợ các chương trình PVM chung được tạo ra bởi Sự hỗ trợ này được cung cấp bởi hai phương pháp được gọi là Khai thác và chú giải. | 126 DISTRIBUTED AND PARALLEL SYSTEMS Figure 1. P-GRADE representation of the quantum scattering program of the figure shows the different parallel execution options available in P-GRADE. The bars corresponding to the slaves are all colored black indicating that there is no idling. We found that during the total execution the slave nodes spend more than 99 percent of the time by doing calculations. Parallelization using P-GRADE 127 Figure 2. PROVE visualization of the last minute of parallel execution of the quantum reactive scattering program from 3min till 3min50sec 5. Summary A quantum reactive scattering program written as a sequential code was parallelized using the P-GRADE graphical environment. P-GRADE made it possible to quickly parallelize the code for users not familiar with message passing based on the following algorithm 1. re-design the parallel algorithm corresponding to the existing sequential code this requires deep understanding how the existing code has been built . 2. separate the FORTRAN or C code into units of the parallel algorithm and compile those subprograms 3. draw the graph of the algorithm using P-GRADE 4. fill in any missing boxes with the necessary program units using C or C within the boxes in P-GRADE if no separate codes are available 5. compile check efficiency and run. This algorithm has proved to be efficient and useful in several applications. Acknowledgments Financial support by the Hungarian Ministry of Education IKTA 00137 and by the Hungarian National Scientific Research Fund OTKA T29726 is 128 DISTRIBUTED AND PARALLEL SYSTEMS gratefully acknowledged. This work is part of the workgroup METACHEM 3 supported by COST of EU. We thank Prof. P. Kacsuk I rs. R. Lovas and G. Hermann for their help with P-GRADE. References 1 A. Laganá A. Riganelli. Computational reaction and molecular dynamics from simple systems and rigorous methods to complex systems and approximate methods it Lecture Notes in Chemistry 75 1-12 2000 2 A. Laganá .