Operating system vendors have been putting out patches for Spector and Meltdown and there has been speculation on the impact of this on users. Does this apply to the simulation community? Rather than speculate, I decided to upgrade computers running Linux, Windows 10 and macOS 10.13.2 and re-run my standard timing tests for ESP-r (12.7) and EnergyPlus (8.8) in order to see if patterns emerged.

Indeed there is a mix of impacts. MacOS sees changes in both tools across a range of tasks, especially disk I/O, Linux updates tends to hit ESP-r more than EnergyPlus while Windows 10 patches impact both tools and hits disk I/O.

If you are curious check out the updated simulation timings web page. Look for the Spector - Meltdown section near the bottom of the page: <>

There are some gaps in the study (does a recomple help?) so I will continue to explore it as time permits -- and then embed the results in the Contrasting Simulation Tools web site <>.

Regards, Jon Hand, Glasgow Scotland