基于1000×1000个原子的Ti薄膜淀积生长过程的模拟,在分布式并行系统上提出了区域重叠划分和异步通信的有效并行计算策略,并运用 Monte Carlo方法实现了模拟真实沉积速率下的大规模薄膜生长的并行计算过程,缩短了薄膜生长模拟计算时间.实现的并行算法能够模拟比以前粒子数大得多的真实沉积速率下薄膜生长问题,从而为运用计算机方法模拟薄膜生长提供了有效的手段.
At present, I/O is the performance bottleneck limiting the speed of computer systems. A large number of I/O operations are synchronous read/write operations of only small data blocks. However, reducing the latency of synchronous I/O operation is a non-trivial problem. In this paper, we propose two methods to address this problem. The first method, FastSync, uses a cache disk optimized for write operation via use of a disk-head position prediction algorithm. In this way, disk capacity is traded for synchronous I/O performance. The second method, LND, uses free memory capacity in a network environment as a cache disk for the buffering of synchronous I/O operation. Data integrity in FastSync is ensured by using a data log on the cache disk, whereas in LND, integrity is ensured by the storage in distributed memory of multiple copies of each data block. Both methods succeed in dramatically increasing the performance of synchronous I/O operation. The performance of LND is limited by the network speed, whereas performance of FastSync is determined mostly by the data block size.
