Read-Copy Update (RCU)

RCU is a synchronization mechanism that is used in the Linux kernel to replace some uses of reader-writer locking and reference counting. The concepts behind RCU are quite simple: At its core, RCU is just a way of waiting for things to get done. However, effective use of RCU does require that you think about concurrency in a different way. RCU is only recently being added to university coursework, but fortunately there is quite a bit of documentation available:

• Documentation/RCU/ in the Linux-kernel source tree.

• A number of LWN articles, including:

  • What is RCU, Fundamentally?

  • What is RCU's Usage?

  • The RCU API, 2010 Edition.

  • Sleepable RCU.

• User-Level Implementations of Read-Copy Update (freely available pre-publication version). See also the freely available supplementary information.

• The wikipedia article.

For additional documentation on RCU, see Documentation/RCU/RTFP.txt in your friendly Linux-kernel source tree.