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From: Dan Williams <dan.j.williams@intel.com>
To: Ric Wheeler <ricwheeler@gmail.com>
Cc: lsf-pc@lists.linux-foundation.org,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	linux-ext4 <linux-ext4@vger.kernel.org>
Subject: Re: [LSF/MM TOPIC] The end of the DAX experiment
Date: Mon, 18 Feb 2019 10:17:30 -0800
Message-ID: <CAPcyv4grMnrviSDJrA5FQOFvxuAMUXoKvgNpdy9sF9zi+OHJNA@mail.gmail.com> (raw)
In-Reply-To: <3eb67ffa-76c9-aa66-d162-d4e209330f48@gmail.com>

On Sun, Feb 17, 2019 at 12:29 PM Ric Wheeler <ricwheeler@gmail.com> wrote:
>
> On 2/6/19 4:12 PM, Dan Williams wrote:
> > Before people get too excited this isn't a proposal to kill DAX. The
> > topic proposal is a discussion to resolve lingering open questions
> > that currently motivate ext4 and xfs to scream "EXPERIMENTAL" when the
> > current DAX facilities are enabled. The are 2 primary concerns to
> > resolve. Enumerate the remaining features/fixes, and identify a path
> > to implement it all without regressing any existing application use
> > cases.
> >
> > An enumeration of remaining projects follows, please expand this list
> > if I missed something:
> >
> > * "DAX" has no specific meaning by itself, users have 2 use cases for
> > "DAX" capabilities: userspace cache management via MAP_SYNC, and page
> > cache avoidance where the latter aspect of DAX has no current api to
> > discover / use it. The project is to supplement MAP_SYNC with a
> > MAP_DIRECT facility and MADV_SYNC / MADV_DIRECT to indicate the same
> > dynamically via madvise. Similar to O_DIRECT, MAP_DIRECT would be an
> > application hint to avoid / minimiize page cache usage, but no strict
> > guarantee like what MAP_SYNC provides.
>
>
> Sounds like a great topic to me. Having just gone through a new round of USENIX
> paper reviews, it is interesting to see how many academic systems are being
> pitched in this space (and most of them don't mention the kernel based xfs/ext4
> with dax).

Makes sense, the current fsdax facility is chasing feature
deficiencies relative to device-dax (longterm pin support) and nova
(dax techniques for fs-metadata).

      reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-06 21:12 Dan Williams
2019-02-07 21:51 ` Kani, Toshi
2019-02-08  9:02   ` Johannes Thumshirn
2019-02-14 13:46 ` [Lsf-pc] " Michal Hocko
2019-02-14 18:25   ` Dan Williams
2019-02-14 19:10     ` Jerome Glisse
2019-02-14 19:31       ` Dan Williams
2019-02-14 20:08         ` Matthew Wilcox
2019-02-14 20:20           ` Dan Williams
2019-02-14 20:34             ` Jerome Glisse
2019-02-16  5:37             ` Dave Chinner
2019-06-05 16:22             ` Goldwyn Rodrigues
2019-06-07  6:00               ` Dan Williams
2019-02-17 20:29 ` Ric Wheeler
2019-02-18 18:17   ` Dan Williams [this message]

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