Some people think that these system calls are a good way to improve the performance
Who does? There seems to be no source given to back up this claim.
I was missing this and other references while reading through.
It’s often used in data systems, as an example memcached allows you to pin all process memory. DBMS often pin pages in their buffer manager to main memory as well to prevent pessimal behaviors due to interaction with the OS buffer cache. It’s a fairly common syscall and often necessary as in the examples above, but the article points out some common pitfalls that are useful to keep in mind.