linux-mm.kvack.org archive mirror
 help / color / mirror / Atom feed
From: Dave Chinner <david@fromorbit.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Christoph Hellwig <hch@infradead.org>,
	Michal Hocko <mhocko@suse.com>,
	"Kirill A. Shutemov" <kirill@shutemov.name>,
	Hugh Dickins <hughd@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v4 00/25] Page folios
Date: Tue, 16 Mar 2021 09:27:08 +1100	[thread overview]
Message-ID: <20210315222708.GA349301@dread.disaster.area> (raw)
In-Reply-To: <20210315194014.GZ2577561@casper.infradead.org>

On Mon, Mar 15, 2021 at 07:40:14PM +0000, Matthew Wilcox wrote:
> I would agree that the conversion is both straightforward and noisy.
> There are some minor things that crop up, like noticing that we get
> the accounting wrong for writeback of compound pages.  That's not
> entirely unexpected since no filesystem supports both compound pages
> and writeback today.

And this is where the abstraction that the "folio" introduces is
required - filesystem people don't want to have to deal with all the
complexity and subtlety of compound pages when large page support is
added to the page cache. As Willy says, this will be a never-ending
source of data corruption bugs....

Hence from the filesystem side of things, I think this abstraction
is absolutely necessary. Especially because handling buffered IO in
4kB pages really, really sucks from a performance persepctive and
the sooner we have native high-order page support in the page cache
the better.  These days buffered IO often can't even max out a cheap
NVMe SSD because of the CPU cost of per-page state management in the
page cache. So the sooner we have large page support to mitigate the
worst of the overhead for streaming buffered IO, the better.

FWIW, like others, I'm not a fan of "folio" as a name, but I can live
with it because it so jarringly different to "pages" that we're not
going to confuse the two of them. But if we want a better name, my
suggestion would be for a "struct cage" as in Compound pAGE....

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com


  reply	other threads:[~2021-03-15 22:29 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-05  4:18 [PATCH v4 00/25] Page folios Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 01/25] mm: Introduce struct folio Matthew Wilcox (Oracle)
2021-03-13 20:37   ` Andrew Morton
2021-03-14  4:07     ` Matthew Wilcox
2021-03-17 17:14   ` Christoph Hellwig
2021-03-18 23:56   ` Balbir Singh
2021-03-19  1:25     ` Matthew Wilcox
2021-03-20  2:09       ` Balbir Singh
2021-03-22  2:52       ` Nicholas Piggin
2021-03-22  3:54         ` Matthew Wilcox
2021-03-05  4:18 ` [PATCH v4 02/25] mm: Add folio_pgdat and folio_zone Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 03/25] mm/vmstat: Add functions to account folio statistics Matthew Wilcox (Oracle)
2021-03-13 20:37   ` Andrew Morton
2021-03-14  4:11     ` Matthew Wilcox
2021-03-14  4:51       ` Andrew Morton
2021-03-17 17:16   ` Christoph Hellwig
2021-03-05  4:18 ` [PATCH v4 04/25] mm/debug: Add VM_BUG_ON_FOLIO and VM_WARN_ON_ONCE_FOLIO Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 05/25] mm: Add put_folio Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 06/25] mm: Add get_folio Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 07/25] mm: Create FolioFlags Matthew Wilcox (Oracle)
2021-03-15  2:24   ` Matthew Wilcox
2021-03-05  4:18 ` [PATCH v4 08/25] mm: Handle per-folio private data Matthew Wilcox (Oracle)
2021-03-17 17:20   ` Christoph Hellwig
2021-03-18 17:57     ` Matthew Wilcox
2021-03-05  4:18 ` [PATCH v4 09/25] mm: Add folio_index, folio_page and folio_contains Matthew Wilcox (Oracle)
2021-03-13 20:37   ` Andrew Morton
2021-03-14  3:45     ` Matthew Wilcox
2021-03-17 17:22     ` Christoph Hellwig
2021-03-05  4:18 ` [PATCH v4 10/25] mm/util: Add folio_mapping and folio_file_mapping Matthew Wilcox (Oracle)
2021-03-17 17:26   ` Christoph Hellwig
2021-03-05  4:18 ` [PATCH v4 11/25] mm/memcg: Add folio wrappers for various memcontrol functions Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 12/25] mm/filemap: Add unlock_folio Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 13/25] mm/filemap: Add lock_folio Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 14/25] mm/filemap: Add lock_folio_killable Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 15/25] mm/filemap: Convert lock_page_async to lock_folio_async Matthew Wilcox (Oracle)
2021-03-17 17:29   ` Christoph Hellwig
2021-03-05  4:18 ` [PATCH v4 16/25] mm/filemap: Convert end_page_writeback to end_folio_writeback Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 17/25] mm/filemap: Add wait_on_folio_locked & wait_on_folio_locked_killable Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 18/25] mm/page-writeback: Add wait_on_folio_writeback Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 19/25] mm/page-writeback: Add wait_for_stable_folio Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 20/25] mm/filemap: Convert wait_on_page_bit to wait_on_folio_bit Matthew Wilcox (Oracle)
2021-03-17 17:39   ` Christoph Hellwig
2021-03-05  4:18 ` [PATCH v4 21/25] mm/filemap: Add __lock_folio_or_retry Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 22/25] mm/filemap: Convert wake_up_page_bit to wake_up_folio_bit Matthew Wilcox (Oracle)
2021-03-05  4:18 ` [PATCH v4 23/25] mm/page-writeback: Convert test_clear_page_writeback to take a folio Matthew Wilcox (Oracle)
2021-03-05  4:19 ` [PATCH v4 24/25] mm/filemap: Convert page wait queues to be folios Matthew Wilcox (Oracle)
2021-03-05  4:19 ` [PATCH v4 25/25] cachefiles: Switch to wait_page_key Matthew Wilcox (Oracle)
2021-03-17 17:45   ` Christoph Hellwig
2021-03-13 20:36 ` [PATCH v4 00/25] Page folios Andrew Morton
2021-03-14  2:30   ` Matthew Wilcox
2021-03-14  3:09   ` Hugh Dickins
     [not found]     ` <20210315115501.7rmzaan2hxsqowgq@box>
2021-03-15 13:45       ` Matthew Wilcox
     [not found]       ` <YE9VLGl50hLIJHci@dhcp22.suse.cz>
2021-03-15 19:09         ` Christoph Hellwig
2021-03-15 19:40           ` Matthew Wilcox
2021-03-15 22:27             ` Dave Chinner [this message]
2021-03-17 17:48             ` Christoph Hellwig
2021-03-15 21:33         ` Andi Kleen
2021-03-19  4:01 ` Matthew Wilcox

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210315222708.GA349301@dread.disaster.area \
    --to=david@fromorbit.com \
    --cc=akpm@linux-foundation.org \
    --cc=hch@infradead.org \
    --cc=hughd@google.com \
    --cc=kirill@shutemov.name \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@suse.com \
    --cc=willy@infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).