From: Dan Williams <dan.j.williams@intel.com>
To: willy@bombadil.infradead.org
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
lsf-pc@lists.linux-foundation.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
linux-block@vger.kernel.org, Linux MM <linux-mm@kvack.org>
Subject: Re: [LSF/MM TOPIC] Future direction of DAX
Date: Tue, 17 Jan 2017 22:25:42 -0800 [thread overview]
Message-ID: <CAPcyv4gvMzPbqpotKTRYhuiRgKRUz-Xrz81MFjpBmh3i=8euFQ@mail.gmail.com> (raw)
In-Reply-To: <20170118060740.GE18349@bombadil.infradead.org>
On Tue, Jan 17, 2017 at 10:07 PM, <willy@bombadil.infradead.org> wrote:
> On Tue, Jan 17, 2017 at 10:01:30PM -0800, Dan Williams wrote:
>> >> - Jan suggested [2] that we could use the radix tree as a cache to service DAX
>> >> faults without needing to call into the filesystem. Are there any issues
>> >> with this approach, and should we move forward with it as an optimization?
>> >
>> > Ahem. I believe I proposed this at last year's LSFMM. And I sent
>> > patches to start that work. And Dan blocked it. So I'm not terribly
>> > amused to see somebody else given credit for the idea.
>>
>> I "blocked" moving the phys to virt translation out of the driver
>> since that mapping lifetime is device specific.
>
> The problem is that DAX currently assumes that there *is* a block driver,
> and it might be a char device or no device at all (the two examples I
> gave earlier).
>
>> However, I think caching the file offset to physical sector/address
>> result is a great idea.
>
> OK, great. The lifetime problem I think you care about (hotplug) can be
> handled by removing all the cached entries for every file on every file
> on that block device ... I know there were prototype patches for that;
> did they ever get merged?
No, they didn't.. The last review comment was from Al. He wanted the
mechanism converted from explicit calls at del_gendisk() time into a
notifier chain since it's not just filesystems that may want to
register for a block-device end-of-life event.
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next prev parent reply other threads:[~2017-01-18 6:25 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-14 0:20 [LSF/MM TOPIC] Future direction of DAX Ross Zwisler
2017-01-14 8:26 ` Darrick J. Wong
2017-01-16 0:19 ` Viacheslav Dubeyko
2017-01-16 20:00 ` Jeff Moyer
2017-01-17 1:50 ` Darrick J. Wong
2017-01-17 2:42 ` Dan Williams
2017-01-17 7:57 ` Christoph Hellwig
2017-01-17 14:54 ` Jeff Moyer
2017-01-17 15:06 ` Christoph Hellwig
2017-01-17 16:07 ` Jeff Moyer
2017-01-17 15:59 ` [Lsf-pc] " Jan Kara
2017-01-17 16:56 ` Dan Williams
2017-01-18 0:03 ` Kani, Toshimitsu
2017-01-18 5:25 ` willy
2017-01-18 6:01 ` Dan Williams
2017-01-18 6:07 ` willy
2017-01-18 6:25 ` Dan Williams [this message]
2017-01-18 17:22 ` Ross Zwisler
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