MultiStage Approaches for Optimal Offline Checkpointing
MultiStage Approaches for Optimal Offline Checkpointing
复制标题
最佳离线检查点的多阶段方法
DOI：
10.1137/080718036
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
A. Walther
中科院分区：
文献类型：
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作者：
Philipp Stumm;A. Walther
优化时变流问题的导数计算通常基于伴随微分方程的积分。为此，需要完整的正演解的知识。在流控制领域，特别是对于三维问题，由于缺乏存储容量，可能不可能跟踪完整的正向解。解决这个问题的一个常用方法是检查点。使用检查点策略，只有部分前向解被保存在主存储器中，并且必须执行额外的时间步长。如果扩展这种方法，使得一些检查点也可以存储在磁盘上，则可以减少附加时间步长的数量。另一方面，必须考虑到一个检查点的访问成本。在并行机器上，可以使用并行I/O设施来存储和检索检查点。在这些情况下，检查站的通行费用也不再可以忽略不计。因此，在本文中，在一个二项式检查点的方法，每个检查点的写和读计数进行检查。这样，检查站的总体访问成本最小化。数值结果说明了派生的检查点方法。他们还表明，检查点技术可能会减少整体计算时间，尽管需要重新计算。
The computation of derivatives for optimizing time-dependent flow problems is often based on the integration of the adjoint differential equation. For this purpose, the knowledge of the complete forward solution is required. In the area of flow control, especially for three-dimensional problems, it may be impossible to keep track of the full forward solution due to the lack of storage capacities. One usual method to overcome this problem is checkpointing. Using a checkpointing strategy, only parts of the forward solution are kept in the main memory and additional time steps have to be performed. If one extends this approach such that some checkpoints can be stored on disc too, one can reduce the number of additional time steps. On the other hand, one has to take the access cost to one checkpoint into account. On parallel machines, one may use parallel I/O facilities to store and retrieve checkpoints. In these cases, the access cost of the checkpoints is also no longer negligible. Therefore, in this paper, the write and read counts for each checkpoint in a binomial checkpointing approach are examined. This way, the overall access cost to checkpoints is minimized. Numerical results illustrate the derived checkpointing approaches. They also show that checkpointing techniques may reduce the overall computing time despite the required recalculations.