From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andy Lutomirski <luto@amacapital.net>
Cc: linux-kernel@vger.kernel.org,
Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: Are there u32 atomic bitops? (or dealing w/ i_flags)
Date: Tue, 18 Dec 2012 01:57:05 +0000 [thread overview]
Message-ID: <20121218015705.GH4939@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CALCETrXs15M-cJRGD_R7fXBxOXR=Pyqsh2dVC78DgShxwn60nA@mail.gmail.com>
On Mon, Dec 17, 2012 at 05:10:21PM -0800, Andy Lutomirski wrote:
> I want to change inode->i_flags access to be atomic -- there are some
> locking oddities right now, I think, and I want to use a new inode
> flag to signal mtime updates from page_mkwrite. The problem is that
> i_flags is an unsigned int, and making it an unsigned long seems like
> a waste, but there aren't any u32 atomic bitops.
... and atomic accesses cost more. A lot more on some architectures.
FWIW, atomic_t *is* 32bit on 32bit architectures, which still doesn't
make it a good idea.
next prev parent reply other threads:[~2012-12-18 1:57 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-18 1:10 Are there u32 atomic bitops? (or dealing w/ i_flags) Andy Lutomirski
2012-12-18 1:34 ` Ming Lei
2012-12-18 1:57 ` Al Viro [this message]
2012-12-18 2:42 ` Andy Lutomirski
2012-12-18 21:30 ` Dave Chinner
2012-12-18 22:20 ` Andy Lutomirski
2012-12-20 7:03 ` Dave Chinner
2012-12-20 20:05 ` Andy Lutomirski
2012-12-20 23:10 ` [RFC PATCH 0/4] Rework mtime and ctime updates on mmaped writes Andy Lutomirski
2012-12-20 23:10 ` [RFC PATCH 1/4] mm: Explicitly track when the page dirty bit is transferred from a pte Andy Lutomirski
2012-12-20 23:10 ` [RFC PATCH 2/4] mm: Update file times when inodes are written after mmaped writes Andy Lutomirski
2012-12-21 0:14 ` Dave Chinner
2012-12-21 0:58 ` Jan Kara
2012-12-21 1:12 ` Dave Chinner
2012-12-21 1:36 ` Jan Kara
2012-12-21 5:36 ` Andy Lutomirski
2012-12-21 10:51 ` Jan Kara
2012-12-21 18:26 ` Andy Lutomirski
2012-12-21 0:34 ` Jan Kara
2012-12-21 5:42 ` Andy Lutomirski
2012-12-21 11:03 ` Jan Kara
2012-12-20 23:10 ` [RFC PATCH 3/4] Remove file_update_time from all mkwrite paths Andy Lutomirski
2012-12-20 23:10 ` [RFC PATCH 4/4] ext4: Fix an incorrect comment about i_mutex Andy Lutomirski
2012-12-20 23:42 ` Jan Kara
2012-12-20 23:36 ` Are there u32 atomic bitops? (or dealing w/ i_flags) Dave Chinner
2012-12-20 23:42 ` Andy Lutomirski
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