Re: kernel changes

[arjan@fenrus.demon.nl]

In article <Pine.LNX.4.20.0109290937510.18362-100000@otter.mbay.net> you wrote:

> One aspect that bothers me is the absence of a success criteria.

I disagree here. Red Hat uses "must pass the cerberus test" as one of the
criteria for kernels. The are other similar criteria, most are obvious (must
boot :). All other distributions have similar tests and a few even use the
cerberus testsuite as well.

Maybe your problem is "absence of tests before Linus releases", well 
even that isn't fully true as distros run these tests on -pre kernels as
well (or -ac kernels, which are mostly in sync with -pre kernels)...

> The current competition for best VM is a good example. The fact is that
> every operating system will fail with a high enough load. The best you can
> hope for is a better degradation then the prior release.

There are a few basic creteria here as well, and 2.4.10 fails on some of
them so far:

1) Must not kill processes as long as there is plenty of swap
   or (possibly dirty) cache memory
2) Must not deadlock (as that is a code-bug)
3) Must not livelock without any progress

Note that no 2.4 kernel so far really achieves 1) in the presence of
highmem; the obvious deadlocks are just pushed further by tuning.

> At the moment both 2.4.10 and 2.4.9-ac16 are better then 2.2.19. But
> people keep testing under higher and higher loads and (surprise) they both
> fail... initiating a search for better degradation logic.

2.4.10 isn't better than 2.2.19 given the criteria above. 2.4.10aa2 might
be though... and 2.4.9acX+Rik's patches are solid in testing. 

Greetings,
   Arjan van de Ven