Deterministic multithreading

An interesting paper appearing in ASPLOS proceedings provides a “deterministic” locking method

Kendo enforces a deterministic interleaving of lock acquisitions and specially declared non-protected reads through a novel dynamically load-balanced deterministic scheduling algorithm. The algorithm tracks the progress of each thread using performance counters to construct a deterministic logical time that is used to compute an interleaving of shared data accesses that is both deterministic and provides good load balancing. Kendo can run on today’s commodity hardware while incurring only a modest performance cost ( http://www.gigascale.org/pubs/1883/asplos073-olszewski.pdf)

There is similarly motivated work on Java going on at UIC: http://dpj.cs.uiuc.edu/DPJ/Home.html

Both works refer to Lee’s paper which I discussed earlier. Nondeterministic threading is a  historical accident in computer engineering. Operating systems introduced time-sharing methods so single thread programs could be run in parallel during I/O delays and then so that multiple users could reasonably fairly share a processor and then so the OS and service programs could provide multiple services to a user at the price of slowing down user applications.  Exposing this system to users has been a mixed blessing. Certainly in the controls world, non-determinism is a dangerous fault.