From: Matthew Wilcox <willy@infradead.org>
To: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>,
kirill.shutemov@linux.intel.com, aarcange@redhat.com,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH] mm: shmem: allow split THP when truncating THP partially
Date: Wed, 26 Feb 2020 17:16:54 -0800 [thread overview]
Message-ID: <20200227011654.GF24185@bombadil.infradead.org> (raw)
In-Reply-To: <cba16817-8555-f84f-134a-1ff9f168247b@linux.alibaba.com>
On Wed, Feb 26, 2020 at 09:43:53AM -0800, Yang Shi wrote:
> > No. The pagevec_lookup_entries() calls from mm/truncate.c prefer the
> > new behavior - evicting the head from page cache removes all the tails
> > along with it, so getting the tails a waste of time there too, just as
> > it was in shmem_undo_range().
>
> TBH I'm not a fun of this hack. This would bring in other confusion or
> complexity. Pagevec is supposed to count in the number of base page, now it
> would treat THP as one page, and there might be mixed base page and THP in
> one pagevec. But, I tend to agree avoiding getting those 14 extra pins at
> the first place might be a better approach. All the complexity are used to
> release those extra pins.
My long-term goal is to eradicate tail pages entirely, so a pagevec will
end up containing pages of different sizes. If you want to help move
in this direction, I'd be awfully grateful. But I wouldn't say that's
in any way a prerequisite for fixing this current problem.
next prev parent reply other threads:[~2020-02-27 1:17 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 0:42 Yang Shi
2019-12-05 0:15 ` Hugh Dickins
2019-12-05 0:50 ` Yang Shi
2020-01-14 19:28 ` Yang Shi
2020-02-04 23:27 ` Yang Shi
2020-02-14 0:38 ` Yang Shi
2020-02-14 15:40 ` Kirill A. Shutemov
2020-02-14 17:17 ` Yang Shi
2020-02-25 3:46 ` Hugh Dickins
2020-02-25 18:02 ` David Hildenbrand
2020-02-25 20:31 ` Hugh Dickins
2020-02-26 17:43 ` Yang Shi
2020-02-27 1:16 ` Matthew Wilcox [this message]
2020-02-27 1:47 ` Hugh Dickins
2020-02-27 1:37 ` Hugh Dickins
2020-02-20 18:16 ` Alexander Duyck
2020-02-21 9:07 ` Michael S. Tsirkin
2020-02-21 9:36 ` David Hildenbrand
2020-02-22 0:39 ` Alexander Duyck
2020-02-24 10:22 ` David Hildenbrand
2020-02-25 0:13 ` Alexander Duyck
2020-02-25 8:09 ` David Hildenbrand
2020-02-25 16:42 ` Alexander Duyck
2020-02-21 18:24 ` Yang Shi
2020-02-22 0:24 ` Alexander Duyck
2020-02-26 17:31 ` Yang Shi
2020-02-26 17:45 ` David Hildenbrand
2020-02-26 18:00 ` Yang Shi
2020-02-27 0:56 ` Hugh Dickins
2020-02-27 1:14 ` Yang Shi
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