From: Christoph Hellwig <hch@infradead.org>
To: Ross Zwisler <ross.zwisler@linux.intel.com>,
Christoph Hellwig <hch@lst.de>,
Dave Chinner <david@fromorbit.com>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org,
"Darrick J. Wong" <darrick.wong@oracle.com>,
"J. Bruce Fields" <bfields@fieldses.org>,
Dan Williams <dan.j.williams@intel.com>,
Jeff Layton <jlayton@poochiereds.net>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-nvdimm@lists.01.org, linux-xfs@vger.kernel.org
Subject: Re: [PATCH 1/7] xfs: always use DAX if mount option is used
Date: Tue, 26 Sep 2017 23:40:01 -0700 [thread overview]
Message-ID: <20170927064001.GA27601@infradead.org> (raw)
In-Reply-To: <20170926173057.GB20159@linux.intel.com>
On Tue, Sep 26, 2017 at 11:30:57AM -0600, Ross Zwisler wrote:
> I agree that Christoph's idea about having the system intelligently adjust to
> use DAX based on performance information it gathers about the underlying
> persistent memory (probably via the HMAT on x86_64 systems) is interesting,
> but I think we're still a ways away from that.
So what are the missing blockers for a getting started?
> FWIW, as my patches suggest and Jan observed I think that we should allow
> users to turn on DAX by treating the inode flag and the mount flag as an 'or'
> operation. i.e. you get DAX if either the mount option is specified or if the
> inode flag is set, and you can continue to manipulate the per-inode flag as
> you want regardless of the mount option. I think this provides maximum
> flexibility of the mechanism to select DAX without enforcing policy.
IFF we stick to the dax flag that's the only workable way. The only
major issue I still see with that is that this allows unprivilegued
users to enable DAX on a any file they own / have write access to.
So there isn't really any way to effectively disable the DAX path
by the sysadmin.
> Does it make sense at this point to just start a "dax" man page that can
> contain info about the mount options, inode flags, kernel config options, how
> to get PMDs, etc? Or does this documentation need to be sprinkled around more
> in existing man pages?
A dax manpage would be good.
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next prev parent reply other threads:[~2017-09-27 6:40 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-25 23:13 [PATCH 0/7] re-enable XFS per-inode DAX Ross Zwisler
2017-09-25 23:13 ` [PATCH 1/7] xfs: always use DAX if mount option is used Ross Zwisler
2017-09-25 23:38 ` Dave Chinner
2017-09-26 9:35 ` Jan Kara
2017-09-26 11:09 ` Dave Chinner
2017-09-26 14:37 ` Christoph Hellwig
2017-09-26 17:30 ` Ross Zwisler
2017-09-26 19:48 ` Darrick J. Wong
2017-09-26 22:00 ` Dave Chinner
2017-09-27 6:40 ` Christoph Hellwig [this message]
2017-09-27 16:15 ` Ross Zwisler
2017-10-01 8:17 ` Christoph Hellwig
2017-09-26 18:02 ` Eric Sandeen
2017-09-26 18:50 ` Ross Zwisler
2017-09-25 23:13 ` [PATCH 2/7] xfs: validate bdev support for DAX inode flag Ross Zwisler
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 17:16 ` Ross Zwisler
2017-09-26 17:57 ` Darrick J. Wong
2017-09-25 23:14 ` [PATCH 3/7] xfs: protect S_DAX transitions in XFS read path Ross Zwisler
2017-09-25 23:27 ` Dave Chinner
2017-09-26 6:32 ` Christoph Hellwig
2017-09-26 13:59 ` Dan Williams
2017-09-26 14:33 ` Christoph Hellwig
2017-09-26 18:11 ` Dan Williams
2017-10-01 8:17 ` Christoph Hellwig
2017-09-25 23:14 ` [PATCH 4/7] xfs: protect S_DAX transitions in XFS write path Ross Zwisler
2017-09-25 23:29 ` Dave Chinner
2017-09-25 23:14 ` [PATCH 5/7] xfs: introduce xfs_is_dax_state_changing Ross Zwisler
2017-09-26 6:33 ` Christoph Hellwig
2017-09-25 23:14 ` [PATCH 6/7] mm, fs: introduce file_operations->post_mmap() Ross Zwisler
2017-09-25 23:38 ` Dan Williams
2017-09-26 18:57 ` Ross Zwisler
2017-09-26 19:19 ` Dan Williams
2017-09-26 21:06 ` Ross Zwisler
2017-09-26 21:41 ` Dan Williams
2017-09-27 11:35 ` Jan Kara
2017-09-27 14:00 ` Dan Williams
2017-09-27 15:07 ` Jan Kara
2017-09-27 15:36 ` Dan Williams
2017-09-27 15:39 ` Ross Zwisler
2017-09-27 15:54 ` Dan Williams
2017-09-26 6:34 ` Christoph Hellwig
2017-09-25 23:14 ` [PATCH 7/7] xfs: re-enable XFS per-inode DAX Ross Zwisler
2017-09-26 0:31 ` Dave Chinner
2017-09-26 6:36 ` Christoph Hellwig
2017-09-26 19:01 ` Ross Zwisler
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