What is RCU, Fundamentally?

Thank you for providing the link -- much better than my old hard copy!  It is very good indeed
to see some of these older papers becoming available on the web.

There was indeed some memory-consistency-model research done some decades ago.  Although I
cannot claim comprehensive knowledge of memory-model research, as near as I can tell, almost
all of this older research was swept aside by the notion of sequential consistency in 1979.
The lion's share of later research assumed sequential consistency, which rendered this research
less than helpful on weakly-ordered machines, where "weakly ordered" includes x86.  Algorithms
that fail to work on x86 cannot be said to have much practical value, in my opinion.

There were nevertheless some fundamental papers published in the 90s (e.g., Sarita Adve and
Kourosh Gharachorloo, among others), but many of the researchers focused on "how to emulate
sequential consistency on weak-memory machines" as opposed to "how best to express
memory-ordering constraints while allowing efficient code to be generated for systems with a
wide variety of memory consistency models".  It is this latter statement that the C/C++
standards committee must address.