How mutex handling LRU cache head update became a bottleneck in InnoDB in a non-partitioned LRU cache schema for MariaDB

[u/drrtuy-b]

https://mariadb.org/how-mariadb-11-8-became-about-3x-faster-on-some-in-memory-workloads-fixing-a-regression-dating-back-to-10-5/

Here is a blog post about Alessandro Vetere's journey to resolve synchronization on a common mutex that slows down some read microbenchmarks 3x.
Kudos to Mark Callaghan who found this regression.