Message-ID: <538DF836.5000206@ontolinux.com>
Date: Tue, 03 Jun 2014 18:30:46 +0200
From: Christian Stroetmann <stroetmann@ontolinux.com>
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To: "Theodore Ts'o" <tytso@mit.edu>
CC: Dave Chinner <david@fromorbit.com>, Daniel Phillips <daniel@phunq.net>,
        Linux Kernel <linux-kernel@vger.kernel.org>,
        Linux FS Devel <linux-fsdevel@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Subject: Re: [RFC][PATCH 1/2] Add a super operation for writeback
References: <538B9DEE.20800@phunq.net> <538C360F.7020901@ontolinux.com> <20140603033940.GB14410@dastard> <538D5D78.6040102@ontolinux.com> <20140603145749.GB12890@thunk.org>
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On the 3rd of June 2014 16:57, Theodore Ts'o wrote:
> On Tue, Jun 03, 2014 at 07:30:32AM +0200, Christian Stroetmann wrote:
>> In general, I do not believe that the complexity problems of soft updates,
>> atomic writes, and related techniques can be solved by hand/manually. So my
>> suggestion is to automatically handle the complexity problem of e.g.
>> dependancies in a way that is comparable to a(n on-the-fly) file-system
>> compiler so to say that works on a very large dependancy graph (having
>> several billions of graph vertices actually). And at this point an
>> abstraction like it is given with Featherstitch helps to feed and control
>> this special FS compiler.
> Well, if you want to try to implement something like this, go for it!

I am already active since some weeks.

> I'd be very curious to see how well (a) how much CPU overhead it takes
> to crunch on a dependency graph with billions of vertices, and (b) how
> easily can it be to express these dependencies and maintainable such a
> dependency language would be.  Sounds like a great research topic, and

To a) A run is expected to take some few hours on a single computing node.

Also, such a graph processing must not be done all the time, but only if 
a new application demands a specific handling of the data in respect to 
e.g. one of the ACID criterias. That is the reason why I put 
"on-the-fly" in paranthesis.

To b) I hoped that file system developers could make some suggestions or 
point to some no-gos.
I am also thinking about Petri-Nets in this relation, though it is just 
an idea.

I would also like to mention that it could be used in conjunction with 
Non-Volatile Memory (NVM) as well.

> I'll note the Call For Papers for FAST 2015 is out, and if you can
> solve these problems, it would make a great FAST 2015 submission:
>
> https://www.usenix.org/conference/fast15/call-for-papers

Are you serious or have I missed the 1st of April once again?
Actually, I could only write a general overview about the approach 
comparable to a white paper, but nothing more.

> Cheers,
>
> 					- Ted
>

Best regards
Christian
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