From: Mike Snitzer <snitzer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: Jan Kara <jack-AlSwsSmVLrQ@public.gmane.org>,
"linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org"
<linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org>,
chengnt <chengnt-6jq1YtArVR3QT0dZR+AlfA@public.gmane.org>,
Dave Chinner <david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org>,
colyli <colyli-l3A5Bk7waGM@public.gmane.org>,
"dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
Mikulas Patocka
<mpatocka-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
"linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: Snapshot target and DAX-capable devices
Date: Wed, 12 Dec 2018 12:50:47 -0500 [thread overview]
Message-ID: <20181212175047.GA24962@redhat.com> (raw)
In-Reply-To: <20181212161254.GA20790-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
On Wed, Dec 12 2018 at 11:12am -0500,
Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org> wrote:
> Does it really make sense to enhance dm-snapshot? I thought all serious
> users of snapshots had moved on to dm-thinp?
There are cases where dm-snapshot is still useful for people. But those
are very niche users. I'm not opposed to others proposing enhancements
for dm-snapshot in general but it is definitely not a priority (Google's
dm-bow is an example of a case where dm-snapshot may get extended to
fulfill google's needs).
But for this specific DAX case, I can only assume efforts to prop up
dm-snapshot like this are born out of legacy use-cases. The reality is
getting DAX to work with dm-snapshot is pretty involved (due to mmap,
etc). This thread got into a lot of the details:
https://www.redhat.com/archives/dm-devel/2018-August/msg00211.html
So any new attempt to reintroduce DAX support to dm-snapshot (or any
more complex DM target) will have a very high bar. One that requires
much more extensive mm and block (interlock) prep work to make DAX
safe.
Mike
WARNING: multiple messages have this Message-ID (diff)
From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jan Kara <jack@suse.cz>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
chengnt <chengnt@lenovo.com>, Dave Chinner <david@fromorbit.com>,
colyli <colyli@suse.de>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
Mikulas Patocka <mpatocka@redhat.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: Snapshot target and DAX-capable devices
Date: Wed, 12 Dec 2018 12:50:47 -0500 [thread overview]
Message-ID: <20181212175047.GA24962@redhat.com> (raw)
In-Reply-To: <20181212161254.GA20790@infradead.org>
On Wed, Dec 12 2018 at 11:12am -0500,
Christoph Hellwig <hch@infradead.org> wrote:
> Does it really make sense to enhance dm-snapshot? I thought all serious
> users of snapshots had moved on to dm-thinp?
There are cases where dm-snapshot is still useful for people. But those
are very niche users. I'm not opposed to others proposing enhancements
for dm-snapshot in general but it is definitely not a priority (Google's
dm-bow is an example of a case where dm-snapshot may get extended to
fulfill google's needs).
But for this specific DAX case, I can only assume efforts to prop up
dm-snapshot like this are born out of legacy use-cases. The reality is
getting DAX to work with dm-snapshot is pretty involved (due to mmap,
etc). This thread got into a lot of the details:
https://www.redhat.com/archives/dm-devel/2018-August/msg00211.html
So any new attempt to reintroduce DAX support to dm-snapshot (or any
more complex DM target) will have a very high bar. One that requires
much more extensive mm and block (interlock) prep work to make DAX
safe.
Mike
_______________________________________________
Linux-nvdimm mailing list
Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Huaisheng Ye <yehs2007@zoho.com>, Jan Kara <jack@suse.cz>,
Dave Chinner <david@fromorbit.com>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>,
"dm-devel@redhat.com" <dm-devel@redhat.com>,
Mikulas Patocka <mpatocka@redhat.com>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
chengnt <chengnt@lenovo.com>, yehs1 <yehs1@lenovo.com>,
colyli <colyli@suse.de>
Subject: Re: Snapshot target and DAX-capable devices
Date: Wed, 12 Dec 2018 12:50:47 -0500 [thread overview]
Message-ID: <20181212175047.GA24962@redhat.com> (raw)
In-Reply-To: <20181212161254.GA20790@infradead.org>
On Wed, Dec 12 2018 at 11:12am -0500,
Christoph Hellwig <hch@infradead.org> wrote:
> Does it really make sense to enhance dm-snapshot? I thought all serious
> users of snapshots had moved on to dm-thinp?
There are cases where dm-snapshot is still useful for people. But those
are very niche users. I'm not opposed to others proposing enhancements
for dm-snapshot in general but it is definitely not a priority (Google's
dm-bow is an example of a case where dm-snapshot may get extended to
fulfill google's needs).
But for this specific DAX case, I can only assume efforts to prop up
dm-snapshot like this are born out of legacy use-cases. The reality is
getting DAX to work with dm-snapshot is pretty involved (due to mmap,
etc). This thread got into a lot of the details:
https://www.redhat.com/archives/dm-devel/2018-August/msg00211.html
So any new attempt to reintroduce DAX support to dm-snapshot (or any
more complex DM target) will have a very high bar. One that requires
much more extensive mm and block (interlock) prep work to make DAX
safe.
Mike
next prev parent reply other threads:[~2018-12-12 17:50 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-27 16:07 Snapshot target and DAX-capable devices Jan Kara
2018-08-27 16:07 ` Jan Kara
2018-08-27 16:07 ` Jan Kara
[not found] ` <20180827160744.GE4002-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2018-08-27 16:43 ` Kani, Toshi
2018-08-27 16:43 ` Kani, Toshi
2018-08-27 16:43 ` Kani, Toshi
[not found] ` <e38303902267d2d8bae8b0c88da84a4ed668e9fb.camel-ZPxbGqLxI0U@public.gmane.org>
2018-08-28 7:50 ` Jan Kara
2018-08-28 7:50 ` Jan Kara
2018-08-28 7:50 ` Jan Kara
[not found] ` <20180828075025.GA17756-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2018-08-28 17:56 ` Mike Snitzer
2018-08-28 17:56 ` Mike Snitzer
2018-08-28 17:56 ` Mike Snitzer
[not found] ` <20180828175630.GA1197-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-08-28 22:38 ` Kani, Toshi
2018-08-28 22:38 ` Kani, Toshi
2018-08-28 22:38 ` Kani, Toshi
2018-08-30 9:30 ` Jan Kara
2018-08-30 9:30 ` Jan Kara
2018-08-30 9:30 ` Jan Kara
[not found] ` <20180830093028.GC1767-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2018-08-30 18:49 ` Mike Snitzer
2018-08-30 18:49 ` Mike Snitzer
2018-08-30 18:49 ` Mike Snitzer
[not found] ` <20180830184907.GA14867-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-08-30 19:32 ` Jeff Moyer
2018-08-30 19:32 ` Jeff Moyer
2018-08-30 19:32 ` Jeff Moyer
[not found] ` <x494lfbabwi.fsf-RRHT56Q3PSP4kTEheFKJxxDDeQx5vsVwAInAS/Ez/D0@public.gmane.org>
2018-08-30 19:47 ` Mikulas Patocka
2018-08-30 19:47 ` Mikulas Patocka
2018-08-30 19:47 ` Mikulas Patocka
[not found] ` <alpine.LRH.2.02.1808301545200.30950-Hpncn10jQN4oNljnaZt3ZvA+iT7yCHsGwRM8/txMwJMAicBL8TP8PQ@public.gmane.org>
2018-08-30 19:53 ` Jeff Moyer
2018-08-30 19:53 ` Jeff Moyer
2018-08-30 19:53 ` Jeff Moyer
2018-08-30 23:38 ` Dave Chinner
2018-08-30 23:38 ` Dave Chinner
2018-08-30 23:38 ` Dave Chinner
2018-08-31 9:42 ` Jan Kara
2018-08-31 9:42 ` Jan Kara
2018-08-31 9:42 ` Jan Kara
2018-09-05 1:25 ` Dave Chinner
2018-09-05 1:25 ` Dave Chinner
2018-09-05 1:25 ` Dave Chinner
[not found] ` <20180831094255.GB11622-4I4JzKEfoa/jFM9bn6wA6Q@public.gmane.org>
2018-12-12 16:11 ` Huaisheng Ye
2018-12-12 16:11 ` Huaisheng Ye
2018-12-12 16:11 ` Huaisheng Ye
[not found] ` <167a3303a01.11a848ab768799.5161498967766415143-ytc+IHgoah0@public.gmane.org>
2018-12-12 16:12 ` Christoph Hellwig
2018-12-12 16:12 ` Christoph Hellwig
2018-12-12 16:12 ` Christoph Hellwig
[not found] ` <20181212161254.GA20790-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2018-12-12 17:50 ` Mike Snitzer [this message]
2018-12-12 17:50 ` Mike Snitzer
2018-12-12 17:50 ` Mike Snitzer
[not found] ` <20181212175047.GA24962-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-12-12 19:49 ` Kani, Toshi
2018-12-12 19:49 ` Kani, Toshi
2018-12-12 19:49 ` Kani, Toshi
2018-12-12 21:15 ` Theodore Y. Ts'o
2018-12-12 21:15 ` Theodore Y. Ts'o
[not found] ` <20181212211547.GA24926-AKGzg7BKzIDYtjvyW6yDsg@public.gmane.org>
2018-12-12 22:43 ` Mike Snitzer
2018-12-12 22:43 ` Mike Snitzer
2018-12-12 22:43 ` Mike Snitzer
[not found] ` <20181212224321.GA2902-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2018-12-14 4:11 ` [dm-devel] " Theodore Y. Ts'o
2018-12-14 4:11 ` Theodore Y. Ts'o
2018-12-14 4:11 ` Theodore Y. Ts'o
2018-12-14 8:24 ` [External] " Huaisheng HS1 Ye
2018-12-14 8:24 ` Huaisheng HS1 Ye
2018-12-14 8:24 ` Huaisheng HS1 Ye
[not found] ` <HK2PR03MB441871946735DE9EE714D10B92A10-LG58XzHXFHCi7fCZ8j4jr682SN/2zMuYvxpqHgZTriW3zl9H0oFU5g@public.gmane.org>
2018-12-18 19:49 ` Mike Snitzer
2018-12-18 19:49 ` Mike Snitzer
2018-12-18 19:49 ` Mike Snitzer
2018-08-30 19:44 ` Mikulas Patocka
2018-08-30 19:44 ` Mikulas Patocka
2018-08-30 19:44 ` Mikulas Patocka
[not found] ` <alpine.LRH.2.02.1808301537420.30950-Hpncn10jQN4oNljnaZt3ZvA+iT7yCHsGwRM8/txMwJMAicBL8TP8PQ@public.gmane.org>
2018-08-31 10:01 ` Jan Kara
2018-08-31 10:01 ` Jan Kara
2018-08-31 10:01 ` Jan Kara
2018-08-30 22:55 ` Dave Chinner
2018-08-30 22:55 ` Dave Chinner
2018-08-30 22:55 ` Dave Chinner
2018-08-31 9:54 ` Jan Kara
2018-08-31 9:54 ` Jan Kara
2018-08-31 9:54 ` Jan Kara
2018-08-30 19:17 ` [dm-devel] " Jeff Moyer
2018-08-30 19:17 ` Jeff Moyer
2018-08-30 19:17 ` Jeff Moyer
[not found] ` <x498t4naclf.fsf-RRHT56Q3PSP4kTEheFKJxxDDeQx5vsVwAInAS/Ez/D0@public.gmane.org>
2018-08-31 9:14 ` Jan Kara
2018-08-31 9:14 ` Jan Kara
2018-08-31 9:14 ` Jan Kara
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=20181212175047.GA24962@redhat.com \
--to=snitzer-h+wxahxf7alqt0dzr+alfa@public.gmane.org \
--cc=chengnt-6jq1YtArVR3QT0dZR+AlfA@public.gmane.org \
--cc=colyli-l3A5Bk7waGM@public.gmane.org \
--cc=david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org \
--cc=dm-devel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
--cc=hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org \
--cc=jack-AlSwsSmVLrQ@public.gmane.org \
--cc=linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org \
--cc=mpatocka-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.