CLIP: A checkpointing tool for message-passing parallel programs

Checkpointing is a useful technique for rollback recov- ery of parallel applications. While extensive researc h has been performed on checkpointing in parallel envi- ronments, there are few chec kpointers a vailable toap- plication users on commercial parallel computers. This paper presents one such chec kpointer: CLIP. CLIP is a user-lev el library that provides semi-transparent check- pointing for parallel programs on the Intel P aragonmul- ticomputer. It is publicly available to Paragon users at no cost. Conceptually, checkpointing a multicomputer is quite straigh tforward. How ev er, when creating an actual tool for checkpointing a complex machine like the Paragon, many more issues arise that require careful design deci- sions to be made. Sometimes ease-of-use must be sac- rificed for efficiency and/or correctness. This paper de- tails what these decisions are, and how they were made in CLIP. We also present performance data when checkpoint- ing several long-running Paragon applications with CLIP. The bottom line is that a convenient, general-purpose chec kpointing tool like CLIP can provide fault-tolerance on a massively parallel multicomputer like the Paragon with very good performance.