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From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>, Jan Kara <jack@suse.cz>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Dave Chinner <david@fromorbit.com>,
	Christoph Hellwig <hch@lst.de>,
	"Theodore Y. Ts'o" <tytso@mit.edu>,
	linux-ext4 <linux-ext4@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [RFC PATCH V2 01/12] fs/stat: Define DAX statx attribute
Date: Thu, 16 Jan 2020 14:19:06 -0800
Message-ID: <20200116221906.GF8247@magnolia> (raw)
In-Reply-To: <20200116185235.GE24522@iweiny-DESK2.sc.intel.com>

On Thu, Jan 16, 2020 at 10:52:36AM -0800, Ira Weiny wrote:
> On Thu, Jan 16, 2020 at 10:04:21AM -0800, Darrick J. Wong wrote:
> > On Thu, Jan 16, 2020 at 09:55:02AM -0800, Ira Weiny wrote:
> > > On Wed, Jan 15, 2020 at 09:39:35PM -0800, Darrick J. Wong wrote:
> > > > On Wed, Jan 15, 2020 at 02:38:21PM -0800, Ira Weiny wrote:
> > > > > On Wed, Jan 15, 2020 at 12:10:50PM -0800, Dan Williams wrote:
> > > > > > On Wed, Jan 15, 2020 at 11:45 AM Ira Weiny <ira.weiny@intel.com> wrote:
> > > > > > >
> > > > > > > On Wed, Jan 15, 2020 at 09:38:34AM -0800, Darrick J. Wong wrote:
> > > > > > > > On Wed, Jan 15, 2020 at 12:37:15PM +0100, Jan Kara wrote:
> > > > > > > > > On Fri 10-01-20 11:29:31, ira.weiny@intel.com wrote:
> > > > > > > > > > From: Ira Weiny <ira.weiny@intel.com>
> > > > > > > > > >
> > > > > 
> > > 
> > > [snip]
> > > 
> > > > > 
> > > > > Sure, but for now I think referencing mmap for details on MAP_SYNC works.
> > > > > 
> > > > > I suspect that we may have some word smithing once I get this series in and we
> > > > > submit a change to the statx man page itself.  Can I move forward with the
> > > > > following for this patch?
> > > > > 
> > > > > <quote>
> > > > > STATX_ATTR_DAX
> > > > > 
> > > > >         The file is in the DAX (cpu direct access) state.  DAX state
> > > > 
> > > > Hmm, now that I see it written out, I <cough> kind of like "DAX mode"
> > > > better now. :/
> > > > 
> > > > "The file is in DAX (CPU direct access) mode.  DAX mode attempts..."
> > > 
> > > Sure...  now you tell me...  ;-)
> > > 
> > > Seriously, we could use mode here in the man page as this is less confusing to
> > > say "DAX mode".
> > > 
> > > But I think the code should still use 'state' because mode is just too
> > > overloaded.  You were not the only one who was thrown by my use of mode and I
> > > don't want that confusion when we look at this code 2 weeks from now...
> > > 
> > > https://www.reddit.com/r/ProgrammerHumor/comments/852og2/only_god_knows/
> > > 
> > > ;-)
> > 
> > Ok, let's leave it alone for now then.
> 
> Cool could I get a reviewed by?

My bike shed is painted green with purple polka dots,

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> And Jan is this reword of the man page/commit ok to keep your reviewed by?
> 
> > 
> > I'm not even sure what 'DAX' stands for.  Direct Access to ...
> > Professor Xavier? 8-)
> 
> That is pronounced 'Direct A'Xes'  you know, for chopping wood!
> 
> Thanks everyone,
> Ira
> 
> > 
> > > > 
> > > > >         attempts to minimize software cache effects for both I/O and
> > > > >         memory mappings of this file.  It requires a file system which
> > > > >         has been configured to support DAX.
> > > > > 
> > > > >         DAX generally assumes all accesses are via cpu load / store
> > > > >         instructions which can minimize overhead for small accesses, but
> > > > >         may adversely affect cpu utilization for large transfers.
> > > > > 
> > > > >         File I/O is done directly to/from user-space buffers and memory
> > > > >         mapped I/O may be performed with direct memory mappings that
> > > > >         bypass kernel page cache.
> > > > > 
> > > > >         While the DAX property tends to result in data being transferred
> > > > >         synchronously, it does not give the same guarantees of
> > > > >         synchronous I/O where data and the necessary metadata are
> > > > >         transferred together.
> > > > 
> > > > (I'm frankly not sure that synchronous I/O actually guarantees that the
> > > > metadata has hit stable storage...)
> > > 
> > > I'll let you and Dan work this one out...  ;-)
> > 
> > Hehe.  I think the wording here is fine.
> > 
> > --D
> > 
> > > Ira
> > > 

  reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-10 19:29 [RFC PATCH V2 00/12] Enable per-file/directory DAX operations V2 ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 01/12] fs/stat: Define DAX statx attribute ira.weiny
2020-01-15 11:37   ` Jan Kara
2020-01-15 17:38     ` Darrick J. Wong
2020-01-15 19:45       ` Ira Weiny
2020-01-15 20:10         ` Dan Williams
2020-01-15 22:38           ` Ira Weiny
2020-01-16  5:39             ` Darrick J. Wong
2020-01-16  6:05               ` Dan Williams
2020-01-16  6:18                 ` Darrick J. Wong
2020-01-16  6:25                   ` Dan Williams
2020-01-18  9:11                 ` Dave Chinner
2020-01-16 17:55               ` Ira Weiny
2020-01-16 18:04                 ` Darrick J. Wong
2020-01-16 18:52                   ` Ira Weiny
2020-01-16 22:19                     ` Darrick J. Wong [this message]
2020-01-17 11:58                     ` Jan Kara
2020-01-10 19:29 ` [RFC PATCH V2 02/12] fs/xfs: Isolate the physical DAX flag from effective ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 03/12] fs/xfs: Separate functionality of xfs_inode_supports_dax() ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 04/12] fs/xfs: Clean up DAX support check ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 05/12] fs: remove unneeded IS_DAX() check ira.weiny
2020-01-16  9:38   ` Jan Kara
2020-01-16 18:47     ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 06/12] fs/xfs: Check if the inode supports DAX under lock ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 07/12] fs: Add locking for a dynamic inode 'mode' ira.weiny
2020-01-13 22:12   ` Darrick J. Wong
2020-01-14  0:20     ` Ira Weiny
2020-01-14  1:03       ` Darrick J. Wong
2020-01-15 19:08         ` Ira Weiny
2020-01-16  5:40           ` Darrick J. Wong
2020-01-16 18:54             ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 08/12] fs/xfs: Add lock/unlock mode to xfs ira.weiny
2020-01-13 22:19   ` Darrick J. Wong
2020-01-14  0:35     ` Ira Weiny
2020-01-15  0:57       ` Ira Weiny
2020-01-15 23:52     ` Ira Weiny
2020-01-16  9:24   ` Jan Kara
2020-01-16 19:12     ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 09/12] fs: Prevent mode change if file is mmap'ed ira.weiny
2020-01-13 22:22   ` Darrick J. Wong
2020-01-14  0:46     ` Ira Weiny
2020-01-14  1:30       ` Darrick J. Wong
2020-01-14 17:53         ` Ira Weiny
2020-01-15 11:34           ` Jan Kara
2020-01-15 18:24             ` Ira Weiny
2020-01-15 10:21   ` David Laight
2020-01-15 17:53     ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 10/12] fs/xfs: Fix truncate up ira.weiny
2020-01-13 22:27   ` Darrick J. Wong
2020-01-14  0:40     ` Ira Weiny
2020-01-14  1:14       ` Darrick J. Wong
2020-01-14 19:00         ` Ira Weiny
2020-01-14 19:39           ` Ira Weiny
2020-01-10 19:29 ` [RFC PATCH V2 11/12] fs/xfs: Clean up locking in dax invalidate ira.weiny
2020-01-10 19:29 ` [RFC PATCH V2 12/12] fs/xfs: Allow toggle of effective DAX flag ira.weiny

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