Exploring energy saving opportunities in fault tolerant HPC systems

Nowadays, improving the energy efficiency of high-performance computing (HPC) systems is one of the main drivers in scientific and technological research. As large-scale HPC systems require some fault-tolerant method, the opportunities to reduce energy consumption should be explored. In particular, rollback-recovery methods using uncoordinated checkpoints prevent all processes from re-executing when a failure occurs. In this context, it is possible to take actions to reduce the energy consumption of the nodes whose processes do not re-execute. This work is an extension of a previous one, in which we proposed a series of strategies to manage energy consumption at failure-time. In this work, we have enriched our simulator and the experimentation by including non-blocking communications (with and without system buffering) and a largest number of candidate processes to be analyzed. We have called the latter as cascade analysis, because it includes processes that gets blocked by communication indirectly with the failed process. The simulations show that the savings were negligible in the worst case, but in some scenarios, it was possible to achieve significant ones; the maximum saving achieved was 90% in a time interval of 16 minutes. As a result, we show the feasibility of improving energy efficiency in HPC systems in the presence of a failure.