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From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Kent Overstreet <kent.overstreet@gmail.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, Johannes Weiner <hannes@cmpxchg.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Darrick J. Wong" <djwong@kernel.org>,
Christoph Hellwig <hch@infradead.org>,
David Howells <dhowells@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>
Subject: Re: Mapcount of subpages
Date: Sat, 25 Sep 2021 02:05:05 +0300 [thread overview]
Message-ID: <20210924230505.vlql2mdjfcotkuqj@box.shutemov.name> (raw)
In-Reply-To: <72cc2691-5ebe-8b56-1fe8-eeb4eb4a4c74@google.com>
On Thu, Sep 23, 2021 at 02:10:13PM -0700, Hugh Dickins wrote:
> But you have a different point in mind when you refer to superfluous
> CoW and GUP: I don't know the score there (and I think we are still in
> that halfway zone, since pte CoW was changed to depend on page_count,
> but THP CoW still depending on mapcount).
I didn't pay enough attention to the topic when the change to depend on
page_count was made. I need to catch up.
I look at what direction Andrea went in his patchset and so far I *feel*
he has a point[1]. I have not read the whole thing yet and I don't have a
firm position here, but maybe we need to get to the bottom of the topic
before considering ditching per-subpage mapcount.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/andrea/aa.git/tree/mm/memory.c?h=mapcount_deshare&id=e1cb3108d4131c2a7da03fbd37c3230cf082bfd9#n3153
--
Kirill A. Shutemov
next prev parent reply other threads:[~2021-09-24 23:05 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-23 1:21 Struct page proposal Kent Overstreet
2021-09-23 3:23 ` Matthew Wilcox
2021-09-23 5:15 ` Kent Overstreet
2021-09-23 11:40 ` Mapcount of subpages Matthew Wilcox
2021-09-23 12:45 ` Kirill A. Shutemov
2021-09-23 21:10 ` Hugh Dickins
2021-09-23 21:54 ` Yang Shi
2021-09-23 22:23 ` Zi Yan
2021-09-23 23:48 ` Hugh Dickins
2021-09-24 0:25 ` Zi Yan
2021-09-24 0:57 ` Hugh Dickins
2021-09-24 1:11 ` Yang Shi
2021-09-24 1:31 ` Matthew Wilcox
2021-09-24 3:26 ` Yang Shi
2021-09-24 23:05 ` Kirill A. Shutemov [this message]
2021-09-23 18:56 ` Mike Kravetz
2021-09-23 9:03 ` Struct page proposal David Hildenbrand
2021-09-23 15:22 ` Kent Overstreet
2021-09-23 15:34 ` David Hildenbrand
2021-09-27 17:48 ` Vlastimil Babka
2021-09-27 17:53 ` Kent Overstreet
2021-09-27 18:34 ` Linus Torvalds
2021-09-27 20:45 ` David Hildenbrand
2021-09-27 18:05 ` Matthew Wilcox
2021-09-27 18:09 ` Kent Overstreet
2021-09-27 18:12 ` Matthew Wilcox
2021-09-27 18:16 ` David Hildenbrand
2021-09-27 18:53 ` Vlastimil Babka
2021-09-27 19:04 ` Linus Torvalds
2021-09-27 18:16 ` Kent Overstreet
2021-09-28 3:19 ` Matthew Wilcox
2021-09-27 19:07 ` Vlastimil Babka
2021-09-27 20:14 ` Kent Overstreet
2021-09-28 11:21 ` David Laight
2021-09-27 18:33 ` Kirill A. Shutemov
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