From: Christoph Hellwig <hch@infradead.org>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>,
linux-nvdimm <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH] dax: adding fsync/msync support for device DAX
Date: Thu, 5 Apr 2018 01:01:18 -0700 [thread overview]
Message-ID: <20180405080118.GA32396@infradead.org> (raw)
In-Reply-To: <CAPcyv4jn2DHu9HGH=XPr9VHP0gyENFKEiXr=w5hO2UR_tRWc0A@mail.gmail.com>
On Thu, Apr 05, 2018 at 12:56:02AM -0700, Dan Williams wrote:
> Yes, I think it is unfortunate that the failure mode is exposed to
> software at all. The problem is that ADR is a platform feature that
> depends on power supply requirements external to the NVDIMM device. An
> SSD is different. It is a self contained system that can arrange for
> the whole device to fail if the internal energy source fails and
> otherwise hide this detail from software. My personal take, a system
> designer that can specify and qualify an entire stack of components
> can certainly opt-out of advertising the flush capability to the OS
> because, like the SSD vendor, they control the integrated solution. A
> platform vendor that allows off the shelf power supplies would in my
> opinion be remiss not to give the OS the option to mitigate the
> quality of some random power supply. It then follow that if the OS has
> the ability to mitigate ADR failure it should be through a common
> interface between fsdax and devdax.
That means IFF ADR can fail like this we can't treat it as stable
storage and we must not support MAP_SYNC or equivalent device dax
behavior, period.
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
next prev parent reply other threads:[~2018-04-05 8:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-04 22:01 [PATCH] dax: adding fsync/msync support for device DAX Dave Jiang
2018-04-05 0:03 ` Dan Williams
2018-04-05 7:23 ` Christoph Hellwig
2018-04-05 7:56 ` Dan Williams
2018-04-05 8:01 ` Christoph Hellwig [this message]
2018-04-05 14:59 ` Jeff Moyer
2018-04-05 15:10 ` Christoph Hellwig
2018-04-05 22:17 ` Dan Williams
2018-04-06 7:03 ` Christoph Hellwig
2018-04-06 22:41 ` Dan Williams
2018-04-09 9:32 ` Christoph Hellwig
2018-04-11 16:06 ` Jeff Moyer
2018-04-11 16:27 ` Dan Williams
2018-04-11 17:27 ` Jeff Moyer
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180405080118.GA32396@infradead.org \
--to=hch@infradead.org \
--cc=dan.j.williams@intel.com \
--cc=linux-nvdimm@lists.01.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox