Linux-XFS Archive on lore.kernel.org
 help / color / Atom feed
From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: Yu Kuai <yukuai3@huawei.com>,
	hch@infradead.org, darrick.wong@oracle.com,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [RFC PATCH] iomap: add support to track dirty state of sub pages
Date: Fri, 31 Jul 2020 07:59:41 +0100
Message-ID: <20200731065941.GD25674@infradead.org> (raw)
In-Reply-To: <20200730031934.GA23808@casper.infradead.org>

On Thu, Jul 30, 2020 at 04:19:34AM +0100, Matthew Wilcox wrote:
> On Thu, Jul 30, 2020 at 09:19:01AM +0800, Yu Kuai wrote:
> > +++ b/fs/iomap/buffered-io.c
> > @@ -29,7 +29,9 @@ struct iomap_page {
> >  	atomic_t		read_count;
> >  	atomic_t		write_count;
> >  	spinlock_t		uptodate_lock;
> > +	spinlock_t		dirty_lock;
> 
> No need for a separate spinlock.  Just rename uptodate_lock.  Maybe
> 'bitmap_lock'.

Agreed.

> 
> >  	DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
> > +	DECLARE_BITMAP(dirty, PAGE_SIZE / 512);
> 
> This is inefficient and poses difficulties for the THP patchset.
> Maybe let the discussion on removing the ->uptodate array finish
> before posting another patch for review?

I really don't think we can kill the uptodate bit.   But what we can
do is have on bitmap array (flex size as in your prep patches) and just
alternating bits for uptodate and dirty.

      parent reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30  1:19 Yu Kuai
2020-07-30  2:27 ` Gao Xiang
2020-07-30  3:13   ` yukuai (C)
2020-07-30  3:19 ` Matthew Wilcox
2020-07-30  3:39   ` yukuai (C)
2020-07-31  6:59   ` Christoph Hellwig [this message]

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=20200731065941.GD25674@infradead.org \
    --to=hch@infradead.org \
    --cc=darrick.wong@oracle.com \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=willy@infradead.org \
    --cc=yi.zhang@huawei.com \
    --cc=yukuai3@huawei.com \
    /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

Linux-XFS Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-xfs/0 linux-xfs/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-xfs linux-xfs/ https://lore.kernel.org/linux-xfs \
		linux-xfs@vger.kernel.org
	public-inbox-index linux-xfs

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-xfs


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git