Message-Id: <200805011353.19335.rjw@sisk.pl>
Date:	Thu, 1 May 2008 13:53:18 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Willy Tarreau <w@....eu>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Slaby <jirislaby@...il.com>
Subject: Re: Slow DOWN, please!!!

On Thursday, 1 of May 2008, Willy Tarreau wrote:
> On Wed, Apr 30, 2008 at 06:19:56PM -0700, Linus Torvalds wrote:
> > 
> > 
> > On Thu, 1 May 2008, Rafael J. Wysocki wrote:
> > > 
> > > > I do _not_ want to slow down development by setting some kind of "quality 
> > > > bar" - but I do believe that we should keep our quality high, not because 
> > > > of any hoops we need to jump through, but because we take pride in the 
> > > > thing we do.
> > > 
> > > Well, we certainly should, but do we always remeber about it?  Honest, guv?
> > 
> > Hey, guv, do you _honestly_ believe that some kind of ISO-9000-like 
> > process generates quality?
> > 
> > And I dislike how people try to conflate "quality" and "merging speed" as 
> > if there was any reason what-so-ever to believe that they are related.
> > 
> > You (and Andrew) have tried to argue that slowing things down results in 
> > better quality, and I simply don't for a moment believe that. I believe 
> > the exact opposite.
> 
> Note that I'm not necessarily arguing for slowing down, but for reduced
> functional conflicts (which slow down may help but it's not the only
> solution). I think that refining the time resolution might achieve the
> same goal. Instead of merging 10000 changes which each have 1% chance
> of breaking any other area, and have all developers try to hunt bugs
> caused by unrelated changes, I think we could do that in steps.
> 
> To illustrate, instead of changing 100 areas with one of them causing
> breaking in the other ones, and having 100 victims try to hunt the
> bug in 99 other areas, then theirs, and finally insult the faulty
> author, we could merge 50 areas in version X and 50 in X+1 (or 3*33
> or 4*25, etc...). That way, we would only have 50 victims trying to
> find the bug in 49 other areas (or 32 or 24). Less people wasting
> their time will mean faster validation of changes, and possibly
> faster release cycle with better quality.
> 
> People send you their crap every two months. If you accept half of
> it every month, they don't have to sleep on their code, and at the
> same time at most half of them are in trouble during half the time
> (since bugs are found faster).

Well, as far as I'm concerned, that will work too.

> > So if we can get the discussion *away* from the "let's slow things down", 
> > then I'm interested. Because at that point we don't have to fight made-up 
> > arguments about something irrelevant.
> 
> well, is "let's split changes" ok ?

How about:

(1) Merge a couple of trees at a time (one tree at a time would be ideal, but
    that's impossible due to the total number of trees).
(2) After (1) give testers some time to report problems introduced by the
    merge.
(3) Wait until the most urgent problems are resolved.  Revert the offending
    changes if there's no solution within given time.
(4) Repeat for another couple of trees.
(5) Arrange things so that every tree gets merged once every two months.

This would also give us an idea of which trees introduce more problems.

Thanks,
Rafael
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