PQPCkpt: An efficient three level synchronous checkpointing scheme in mobile computing systems

Distributed domino effect-free checkpointing techniques can be divided into two categories: coordinated and communication-induced checkpointing. The former is inappropriate for mobile computing systems because it either forces every mobile host to take a new checkpoint or blocks the underlying computation during the checkpointing process. The latter makes every mobile host take the checkpoint independently. However, each mobile host may need to store multiple local checkpoints in stable storage. This investigation presents a novel three level synchronous checkpointing algorithm that combines the advantages of above two methods for mobile computing systems. The algorithm utilizes pre-synchronization, quasi-synchronization, and post-synchronization techniques and has the following merits: (1) Consistent global checkpoints can be ensured. (2) No mobile host is blocked during checkpointing. (3) Only twice the checkpoint size is required. (4) Power consumption is low. (5) The disconnection problem of mobile hosts can be resolved. (6) Very few mobile hosts in doze mode are disturbed. (7) It is simple and easy to implement. The proposed algorithm's numerical results are also provided in this work for comparison. The comparison reveals that our algorithm outperforms other algorithms in terms of checkpoint overhead, maintained checkpoints, power consumption, and disturbed mobile hosts.