A Framework for Evaluating Software on Reduced Margins Hardware

To improve power efficiency, researchers are experimenting with dynamically adjusting the voltage and frequency margins of systems to just above the minimum required for reliable operation. Traditionally, manufacturers did not allow reducing these margins. Consequently, existing studies use system simulators, or software fault-injection methodologies, which are slow, inaccurate and cannot be applied on realistic workloads. However recent CPUs allow the operation outside the nominal voltage/frequency envelope. We present eXtended Margins eXperiment Manager (XM^2) which enables the evaluation of software on systems operating outside their nominal margins. It supports both bare-metal and OS-controlled execution using an API to control the fault injection procedure and provides automatic management of experimental campaigns. XM^2 requires, on average, 5.6% extra lines of code and increases the application execution time by 2.5%. To demonstrate the flexibility of XM^2, we perform three case studies: two employing bare-metal execution on a raspberry PI, and one featuring a full-fledged software stack (including OS) on an Intel Skylake Xeon processor.