2nd European Workshop on Automatic Differentiation

Thursday November 17- Friday November 18, 2005

Whitworth Conference Centre

Cranfield University (Shrivenham Campus)

Defence Academy of the UK

Shrivenham, Swindon

 Andreas Kowarz and Andrea  Walther

Recent Developments for Checkpointing Strategies

Abstract: With the upcoming version 1.11.0 ADOL-C will feature an extended interface enabling the user to solve mathematical problems using checkpointing strategies. We present the corresponding part of the interface as well as initial runtime measurements and comparisons. Known problems and limitations are addressed in addition.

All checkpointing strategies designed so far are based on the assumption that a negligible effort is needed for reading and writing the so-called checkpoints. However, in some cases even the set of all checkpoints does not fit into the main memory. Then, the underlying assumption of negligible costs for accessing checkpoints becomes invalid. Therefore, we present first results on an extension of the known approaches. The new Multi-Stage Checkpointing is designed to handle situations where checkpoint access costs are neither constant nor negligible. Starting from the known and proven statements for strategies with negligible checkpoint access cost we present our work towards a cost function for the non-trivial case. We also address problems within the current state of our work as well as open questions to be answered on the way towards an optimal and general Multi-Stage Checkpointing solution.

Slides: KowarzNov05.pdf