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

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Message-ID: <ZSSjvLXozGRVWKm+@memverge.com>
Date:   Mon, 9 Oct 2023 21:07:08 -0400
From:   Gregory Price <gregory.price@...verge.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Gregory Price <gourry.memverge@...il.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux-cxl@...r.kernel.org,
        akpm@...ux-foundation.org, sthanneeru@...ron.com,
        ying.huang@...el.com
Subject: Re: [RFC PATCH v2 0/3] mm: mempolicy: Multi-tier weighted
 interleaving

On Wed, Oct 11, 2023 at 10:15:02PM +0100, Matthew Wilcox wrote:
> 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?
> 

... yes, and a smarter person would have just done that first :P

derp derp, thanks, I'll update.

~Gregory