Abstract

Computer systems are undergoing a shift: for many decades they became faster every year, while now they become more concurrent, with multiple processors in everything from smartphones to web servers. These have very subtle behaviour, for which one cannot simply reason in terms of a global-time causality order. For the last few years my colleagues and I have been trying to understanding how multiprocessors behave (and how they should behave), with an interesting mixture of experiment, discussions with IBM and ARM architects, mathematical modelling, and proof. I’ll give a general introduction to some of the phenomena that underlie the systems we use every day, and talk about how a judicious combination of those four approaches can help.