[msanlop]

Nice! I actually worked on this recently for my bachelor project. We got some promising preliminary results that showed performance gains on B-trees by using "delegation" on top of optimistic lock coupling.

The way delegation locks work is by having threads delegate their critical function instead of getting exclusive access to shared memory. Think of a client/server model, where the server executes other core's critical sections. For machines with very high core counts, the result is that the shared memory remains valid in the delegate's cache, instead of each new lock holder getting cache misses and fetching memory from other cores (or worse, other sockets).

[senderista]

Sounds a bit like flat combining?

https://people.csail.mit.edu/shanir/publications/Flat%20Comb...

[msanlop]

Indeed, generally delegation has become to mean that there is a dedicated server thread that executes critical sections. Where as combining indicates that any thread can become a combiner while acquiring a lock, for a certain period of time. For the project, we used queue-based combining, which seems to be similar to the the lock in the paper.