Re: [RFC PATCH v2 0/3] mm: mempolicy: Multi-tier weighted interleaving

[Matthew Wilcox]

On Mon, Oct 09, 2023 at 04:42:56PM -0400, Gregory Price wrote:
> == Mutex to Semaphore change:
> 
> The memory tiering subsystem is extended in this patch set to have
> externally available information (weights), and therefore additional
> controls need to be added to ensure values are not changed (or tiers
> changed/added/removed) during various calculations.
> 
> Since it is expected that many threads will be accessing this data
> during allocations, a mutex is not appropriate.
> 
> Since write-updates (weight changes, hotplug events) are rare events,
> a simple rw semaphore is sufficient.

Given how you're using it, wouldn't the existing RCU mechanism be
better than converting this to an rwsem?