Re: Linux 2.6.21

[mel@skynet.ie (Mel Gorman)]

On (26/04/07 09:40), Linus Torvalds didst pronounce:
> 
> 
> On Thu, 26 Apr 2007, Jan Engelhardt wrote:
> >
> > I really appreciate the lot of -rcs, especially if there are so many 
> > intrusive changes/regressions. Like Andrew, I have a feeling that it 
> > gets buggier, but at least, it seems to be made up every ... two 
> > releases.
> 
> I wouldn't say that, but yes, there is at least *some* tendency to not 
> merge scary stuff after a painful release.
> 
> For example, I can certainly say that after 2.6.21, I'm likely to be very 
> unhappy merging something that isn't "obviously safe". I knew the timer 
> changes were potentially painful, I just hadn't realized just *how* 
> painful they would be (we had some SATA/IDE changes too, of course, it's 
> not all just about the timers, those just ended up being more noticeable 
> to me than some of the other things were).
> 
> > About 2.6.21 - will see, rc has been to my liking.
> 
> I actually hope that 2.6.21 isn't even all that bad, despite all the 
> worries about it. And I may be complaining about the problems the timers 
> caused, but it was definitely something that was not only worth it, it was 
> overdue - and those NO_HZ issues had been brewing literally for years. So 
> considering issues like that, I think we're actually doing fairly well.
> 
> One of the bigger issues is that I think -mm (and I'm pretty sure Andrew 
> will agree with me on this) has really had a rather spotty history. It's 
> been unstable enough at times that I suspect people have largely stopped 
> testing it, with just the most die-hard testers running -mm.
> 

test.kernel.org also picks up -mm and additional machines run -mm
kernels. It doesn't catch everything but a few bugs get rattled out. That
said, it's automated with Andy Whitcroft and Steve Fox kicking it along
periodically. After spending the day tracking just two issues in -mm and
simple ones at that, the lack of testing may be simply because it's really
bloody boring even with the access to an automated system. There is no
avoiding this really, fixing regressions will never be entertaining.

> So -mm is still very useful just because *Andrew* tests it, and finds all 
> kinds of issues with it, but I literally suspect that Andrew himself is 
> personally a big part of that, which is kind of wasteful - we should be 
> able to spread out the pain more. Andrew is also too damn polite when 
> something goes wrong ;)
> 

A few more "you're a spanner" mails probably would not hurt even though
I'm pretty sure I'll receive a fair number of them :/

> So we should have somebody like Christoph running -mm, and when things 
> break, we'll just sic Christoph on whoever broke it, and teach people 
> proper fear and respect! As it is, I think people tend to send things to 
> -mm a bit *too* eagerly, because there is no downside - Andrew is a "cheap 
> date" testing-wise, and always puts out ;)
> 
> 			Linus

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab