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SubjectRe: [RFC PATCH V2 01/12] fs/stat: Define DAX statx attribute
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
> > >

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