Hybrid scheduling to enhance reliability of real time tasks running on reconfigurable devices
Reconfigurable devices (RDs) are extremely advantageous when employed in real time embedded systems. Nonetheless, they are susceptible to soft errors. In a broad sense, the present research addresses the challenge of improving the reliability of independent periodic real time hardware tasks in RDs by utilizing hybrid fault tolerant scheduling. The current paper combines static and dynamic real time scheduling techniques to improve the reliability of the system. First, the proposed algorithm statically schedules primary tasks and preserves area and time for possible backup tasks on the RD. The overlapping of passive backup tasks is possible. Next, at the run time, event triggered dispatcher dynamically determines which candidate backup copy should be selected for configuration on the overloaded preserved areas. Reliability, task deadline, and RD area limitations are the determining factors of backup overloading in the static phase. On the other hand, in the dynamic phase, the execution result of the primary tasks in this case, success or failure is the deciding factor based on which the dispatcher configures the true backup task on the preserved area. Experimental results show that the hybrid scheduling technique enhances the mean time to failure of the system by an average factor of 1.22 in comparison with a similar state of the art study.
The Journal of Supercomputing