Prompted by a recent paper by McGuire et al. on the Linux real-time workshop in 2009, we have independently investigated the (un)predictability of execution time of short instruction sequences on modern CPUs. Our experimental results indicate that instruction execution time is rather deterministic, even on busy systems and virtual machines. We therefore recommend \emph{against} using such methods in applications depending on high-quality sources of randomness (e.g., cryptography).
Download the report and code with dataset.