10.3.3.4 So, What is RCU Really?
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10.3.3.4 So, What is RCU Really?

At its core, RCU is nothing more nor less than an API that supports publication and subscription for insertions, waiting for all RCU readers to complete, and maintenance of multiple versions. That said, it is possible to build higher-level constructs on top of RCU, including the reader-writer-locking, reference-counting, and existence-guarantee constructs listed in the companion article. Furthermore, I have no doubt that the Linux community will continue to find interesting new uses for RCU, just as they do for any of a number of synchronization primitives throughout the kernel.

Of course, a more-complete view of RCU would also include all of the things you can do with these APIs.

However, for many people, a complete view of RCU must include sample RCU implementations. The next section therefore presents a series of ``toy'' RCU implementations of increasing complexity and capability.