Post Syndicated from corbet original https://lwn.net/Articles/1084015/

The kernel’s read-copy-update (RCU) subsystem ensures that data will not be
deleted until it is known that there are no threads holding references to
it. RCU works well and is widely used throughout the kernel, but it can
increase memory use and add significant delays before unused kernel objects
are cleaned up. Hazard pointers are
an alternative approach to lockless data updates that offers better
performance, for some situations at least. The kernel community is
currently considering a
hazard-pointer implementation by Mathieu Desnoyers and Paul McKenney.