Development Model

Development Model

[Chuck Wolber]

Greetings,

For months I have been reading as much as I can about the current 
stable/unstable development model, but still have a question.

Has the Linux Kernel reached a point where the majority of developers feel 
that (at least for now) no *MAJOR* "rip it out, stomp on it, burn it and 
start over" parts of the kernel exist any longer? In other words, do you 
feel that we're in a good place at this point and that incremental 
improvements will rule the day until $COOL_IDEA comes along and requires a 
refactoring of 2.x (where x is an odd number) porportions?


Thank you,

..Chuck..


P.S. Please CC me on replies, as I am not subscribed at this time.

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Re: Development Model

[bert hubert]

> that (at least for now) no *MAJOR* "rip it out, stomp on it, burn it and 
> start over" parts of the kernel exist any longer? In other words, do you 

These ideas continue to exist. This is partly due to increasing skills of
developers but also to the changing environment. You'll find literally
scores of commits that say 'this was a good idea when were were limited to
1024 filedescriptor' or the like.

I think the tty layer has been ready to be ripped out and replaced for the
past 10 years though.

-- 
http://www.PowerDNS.com      Open source, database driven DNS Software 
http://netherlabs.nl              Open and Closed source services

Re: Development Model

[Arjan van de Ven]

On Mon, 2005-04-18 at 22:31 -0700, Chuck Wolber wrote:
> Greetings,
> 
> For months I have been reading as much as I can about the current 
> stable/unstable development model, but still have a question.
> 
> Has the Linux Kernel reached a point where the majority of developers feel 
> that (at least for now) no *MAJOR* "rip it out, stomp on it, burn it and 
> start over" parts of the kernel exist any longer? In other words, do you 
> feel that we're in a good place at this point and that incremental 
> improvements will rule the day until $COOL_IDEA comes along and requires a 
> refactoring of 2.x (where x is an odd number) porportions?


actually we have shown (and I like the model very much, it's a great way
to get many features production ready and in the hand of users/customers
really fast) that it doesn't take an odd number release branch to get
major changes in. Instead it takes careful design and sufficient testing
and review and most of the changes can go in anyway.

A good example is the 4 level page tables... we entirely changed how
pagetables worked (eg added another level) midway the 2.6 series and we
could because of the factors I wrote above. It even didn't majorly
destabilize the 2.6 tree to become unusable (although the change was
obviously not pain free for kernel architecture maintainers). 

The VM got replaced as well on the fly. The tty layer got half fixed and
seems to be in progress to be fixed even more. The scsi layer has gone
through an overhaul with the creation of transport classes etc etc. All
on the fly by doing careful design (eg stepwise), testing and review.

If we can do all that... what WOULD warrant a odd numbered release which
would be out of the hands of users for a long time (resulting in
features not being available for the users for a likewise long time,
which in turn means very little testing etc etc)

Re: Development Model

[Rik van Riel]

On Tue, 19 Apr 2005, Arjan van de Ven wrote:

> actually we have shown (and I like the model very much, it's a great way
> to get many features production ready and in the hand of users/customers
> really fast) that it doesn't take an odd number release branch to get
> major changes in. Instead it takes careful design and sufficient testing
> and review and most of the changes can go in anyway.

Perhaps even more importantly, things get merged one change
at a time, and stabilised one change at a time.  This is a
big change from the even/odd numbered kernel series, where
sometimes a bug crops up without anybody knowing exactly
what change introduced it.

The current development model seems to go much smoother than
anything I've seen before.

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan

Re: Development Model

[Ralf Baechle]

On Tue, Apr 19, 2005 at 03:24:00PM -0400, Rik van Riel wrote:

> The current development model seems to go much smoother than
> anything I've seen before.

It violates conventional wisdom and that psychological thing is the lion
share of why some people feel uneasy about it.

Dealing with the parallel work on 2.4 and 2.5 was very much like the
attempt of drinking from a firehose, so I'm very happy only having only to
deal with 2.6, not 2.7 also.

  Ralf

Re: Development Model

[Florian Weimer]

* Chuck Wolber:

> Has the Linux Kernel reached a point where the majority of developers feel 
> that (at least for now) no *MAJOR* "rip it out, stomp on it, burn it and 
> start over" parts of the kernel exist any longer?

The IP stack is likely to see some development activity, at leat there
are some specs floating around which contain requirements which the
current IP routing implementation cannot match (deterministic
forwarding and things like that).

I don't know if the results will be published and integrated in the
main kernel tree, though.