linux-kernel - Re: [RESEND PATCH v7 00/10] Small-sized THP for anonymous memory

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Message-ID: <ZWVoPT4AZOLJ/eE4@casper.infradead.org>
Date:   Tue, 28 Nov 2023 04:10:37 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Alistair Popple <apopple@...dia.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Ryan Roberts <ryan.roberts@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Yin Fengwei <fengwei.yin@...el.com>,
        Yu Zhao <yuzhao@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Yang Shi <shy828301@...il.com>,
        "Huang, Ying" <ying.huang@...el.com>, Zi Yan <ziy@...dia.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Itaru Kitayama <itaru.kitayama@...il.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        John Hubbard <jhubbard@...dia.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Hugh Dickins <hughd@...gle.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v7 00/10] Small-sized THP for anonymous memory

On Mon, Nov 27, 2023 at 07:20:26PM +1100, Alistair Popple wrote:
> I don't like "large anon folios" because it seems to confuse collegaues
> when explaining that large anon folios are actually smaller than the
> existing Hugetlb/THP size. I suspect this is because they already assume
> large folios are used for THP. I guess this wouldn't be an issue if
> everyone assumed THP was implemented with huge folios, but that doesn't
> seem to be the case for me at least. Likely because the default THP size
> is often 2MB, which is hardly huge.

I find your colleagues confusing.  To me, "huge" seems bigger than
"large".  I don't seem to be the only one:

https://www.quora.com/What-is-the-difference-among-big-large-huge-enormous-and-giant
(for example)

Perhaps the problem is that people have turned "THP" into a thing in its
own right.  So they feel comfortable talking about small THP, medium THP
and large THP and ignoring that there's already a "huge" embedded in THP.

Now if you'll excuse me, I have to put my PIN number into the ATM machine.