linux-kernel - Re: [GIT PULL] Memory folios for v5.15

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Message-ID: <YSXkDFNkgAhQGB0E@infradead.org>
Date:   Wed, 25 Aug 2021 07:32:44 +0100
From:   Christoph Hellwig <hch@...radead.org>
To:     Theodore Ts'o <tytso@....edu>
Cc:     Matthew Wilcox <willy@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Linux-MM <linux-mm@...ck.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] Memory folios for v5.15

On Tue, Aug 24, 2021 at 03:44:48PM -0400, Theodore Ts'o wrote:
> The problem is whether we use struct head_page, or folio, or mempages,
> we're going to be subsystem users' faces.  And people who are using it
> every day will eventually get used to anything, whether it's "folio"
> or "xmoqax", we sould give a thought to newcomers to Linux file system
> code.  If they see things like "read_folio()", they are going to be
> far more confused than "read_pages()" or "read_mempages()".

Are they?  It's not like page isn't some randomly made up term
as well, just one that had a lot more time to spread.

> So if someone sees "kmem_cache_alloc()", they can probably make a
> guess what it means, and it's memorable once they learn it.
> Similarly, something like "head_page", or "mempages" is going to a bit
> more obvious to a kernel newbie.  So if we can make a tiny gesture
> towards comprehensibility, it would be good to do so while it's still
> easier to change the name.

All this sounds really weird to me.  I doubt there is any name that
nicely explains "structure used to manage arbitrary power of two
units of memory in the kernel" very well.  So I agree with willy here,
let's pick something short and not clumsy.  I initially found the folio
name a little strange, but working with it I got used to it quickly.
And all the other uggestions I've seen s far are significantly worse,
especially all the odd compounds with page in it.