July 2021 – Observations from Uppsala

The SAMOS XXI Conference (Virtual)

The International Conference on Embedded Computer Systems: Architectures, Modeling and Simulation (SAMOS) XXI conference took place a couple of weeks ago. Like all other events in the past 18 months, it was virtual due to Covid-19. For more on the background on the SAMOS conference, see my blog post about SAMOS XIX (from 2019). This year, I presented a tutorial about our public release of the Simics simulator and took the chance to listen to most of the other conference talks.

Oljeön – The World’s Oldest Preserved Oil Refinery

With Covid-19 still a bit of an issue, the summer of 2021 is yet another one for “svemester” (Sverige-semester, or Sweden-vacation). There are plenty of things to see, and one place that I finally got to visit was the old oil refinery at Oljeön in Ängelsberg, home to Engelsbergs oljefabrik and the world’s oldest preserved oil refinery dating back to the mid-1870s. It is a beautiful piece of industrial history, well-preserved and with good guided tours.

View of Oljeön from the mainland. The refinery is the yellow building on the right, the darker building on the left is the one remaining oil storage shed

Microsoft Windows memset Optimization – Stores are Free

I recently stumbled on a blog post called Building Faster AMD64 Memset Routines, written by Joe Bialek of the Microsoft Security Response Center (MSRC). The blog describes his efforts to improve the performance of the Windows kernel memset() function, across all sizes of memory to set. The reported optimizations are quite fascinating, and could be summed by avoiding branches even at the cost of doing redundant stores. Basically, stores are free while branches are expensive.