cvs commit: www/en/projects/ideas index.sgml

Alexander Leidinger Alexander at
Fri Jul 28 12:22:36 UTC 2006

Quoting Robert Watson <rwatson at> (from Fri, 28 Jul 2006  
09:52:33 +0100 (BST)):

[moving to hackers at ... feel free to redirect if you think there's a  
more appropriate list]

> On Fri, 28 Jul 2006, Joel Dahl wrote:
>> Modified files:
>>   en/projects/ideas    index.sgml
>> Log:
>> -  Extend the ktrace project with a new task. [1]

[adding some warnings to this project]

Thanks for reviewing and the heads up regarding problems which may  
arise. Yes, we should add them to the entry.

> BTW, a problem that has occurred a number of times in the past is that
> people have approached us with implementations of ideas in the idea
> list that it has later transpired we aren't actually interested in
> (sometimes at all).  I think it might not be a bad idea to sprinkle the

My impression is, that we lack some committers which not only have  
time to review the submissions, but also have the necessary domain  
specific knowledge at the same time.

> idea list with some additional cautionary language -- often ideas
> listed there are things to explore, not to adopt without very careful
> consideration.  For example, the "FPU subsystem overhaul", "Process

Uhm... the FPU one... ok. AFAIK bde reviewed it. I haven't seen the  
review (or I don't remember it), but so far it looks like it would be  
beneficial to commit it (AFAIR). I'm not able to review the code (I  
lack the necessary domain specific knowledge), but I wanted to give it  
a try on my system and then send a mail to arch to get some technical  
reasons why to not commit commit it.

Similar for the new TCP checksumming code. Initially there was a  
problem, it got fixed, and now nobody takes care of it since everyone  
seems to think "it's flawed". At least this is the impression I got.

> checkpointing", "Pluggable disk shceduler", "Magic Symlinks", "NFS
> Lockd (kernel implementation)", and several others -- the task here
> often isn't to port/write the code, the task is to port/write and then
> perform a detailed and careful evaluation of the changes to decide
> whether they are a good idea, and then consider adopting the code only
> if the evaluation suggests it is a good idea and after significant
> refinment.

So far we got not much responses from committers/developers. There's a  
lot of interest in working on some of the entries, but so far we don't  
get much review for the entries/ideas themself. Any refinement is  
welcome and appreciated. So if someone has some thoughts about  
specific entries: please, share them with us.

> Some of the ideas on this list are distinctly "explore this direction
> as a computer scientist, not a code hacker" sorts of problems -- for
> example, the "Process checkpointing" task seems to suggest that if you
> can read the DFBSD repository and write some C code, you're set.  In
> fact, this is not remotely the case.  Checkpointing is a very difficult
> problem in computer science, with little consensus on how it should be
> done (and indeed whether it should be done at all) by general purpose
> operating systems.  Not only that, but we would not adopt the DFBSD
> implementation as-is, as it solves a few of the easy problems, and none
> of the hard ones (i.e., security).  The requirements here aren't just
> the ability to write code, but an understanding of distributed systems,
> our application/execution model, a strong understanding of the
> performance and security requirements, and willingness to not just look
> at code but the extensive research literature on this topic.

AFAIR the process checkpointing in DFly has to be enabled (or am I  
mixing this up with the magic symlinks?) in the kernel. And the man  
page contains some text what is possible and what not, and about  
security implications. Yes, they don't use a model which is able to  
solve all cases, but for some cases where the programs (those which  
don't make heavy use of I/O and thus can open/close I/O channels when  
they are needed) are written to make use of this feature, you can make  
some users happy and the developers can concentrate at the problem at  
hand. So it's one of those 80/20 solutions. While I agree that a 100%  
solution would be nice, I think an implementation of this in -current  
would be nice to have.

> I think people often grab ideas from the list thinking that if
> implemented as described, they will get committed, and this is not the
> case.  In many of the sorts of "scientific" cases it's likely we'll
> look at the results and say, "Oh, that was a bad idea", or maybe
> slightly more likely, "Oh, hmm, not so sure about that".  The existing

Joel and I already talked briefly about an "we don't do that" or "been  
there, done that, wasn't a good idea" page because of this.

> cautionary language captures that there might be disagreements on the
> specifics, but fails to capture that there may be disagreements on the
> fundamental ideas themselves.  I like the ideas list idea a lot, and

Ok, we should change that. Thanks for providing a big picture view for  
those of us which don't see the forest while sitting in front it...

> don't want to see it removed, but I also don't want people getting the
> false impression that this is a "todo" list.  Some items are todo items
> and obvious short-order commit candidates, others are out-there ideas
> that have potential and should be characterized as "high risk" when it
> comes to the results actually being used.  Maybe what we should be
> thinking about is classifying the todo list items into rote items
> (things where the chances of adoption of a decent implementation are
> high, subject to review) and researchy things (where the chances of
> adoption are low, not just because the chances of a good implementation
> are low, but because there are lots of open and very difficult
> questions involved).  This would help prevent misunderstandings, if
> nothing else.

We need some reviewers here... while I'm able to come up with a nice  
technical description of roughly expressed ideas (as long as I get the  
idea), I'm not a TRB and as such aren't aware of every implication.  
And some ideas are expressed in a way which make them sound like it's  
"common knowledge to people which work in this field" (ATM I refer to  
the NFS lockd in kernel implementation idea).

So: helping hands are welcome!

Thanks for taking some time to review some parts of the list.


All great discoveries are made by mistake.
		-- Young    Alexander @ PGP ID = B0063FE7       netchild @  : PGP ID = 72077137

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