[TriLUG] upgrade to 2.4.17!

[Dan Chen]

On Mon, Jan 28, 2002 at 04:28:57PM -0500, John Franklin wrote:
> I don't think there is any wisdom to it.  He tried to put new code into
> a release-line kernel and got burned.  It's taken them from 2.4.10
> to 2.4.17 to get things stable again.

Pardon, but that's slightly misleading. From the stable point of view,
.11 and .15 are both unusable, so that's 6 revisions (.10, .12-.14,
.16-.17). Rik's vm (which I _still_ think is superior though perhaps not
as well-tuned) took 9 revisions.

On top of that, Linus only merged the portions that he felt needed
merging. From both Andrea's and Rik's words, bits were munged. Not
exactly what one would want with such a major subsystem.

Hardly an apples-vs.-apples comparison, however. The matrix of
subsystems that changed in each revision is much too large to carry out
an objective independent benchmark.

In essence, it _is_ "what works, works."

> That said, the new memory code is an improvement and 2.4 will benefit
> from it.  But it was still a bad software engineering decision to drop
> it into release code.

2.4.17 is vastly superior to 2.4.10, agreed. However, by 2.4.9 Linus had
pretty much wrecked Rik's vm (no offense, Linus). Given Linus's track
record of only merging bits he feels "fit," the only sensible decision
was to rip out the entire subsystem and "start anew."

What 2.4.10+ gained was a much simpler (algorithmically, among other
things) "general-case" vm. In the long run, this is much better than
practicing "good" software engineering by dragging out the mess that
unfortunately used to resemble Rik's vm.

I suggest people who are interested in the nuts and bolts take a look at
rmap. http://www.surriel.com/patches/

-- 
Dan Chen                 crimsun at email.unc.edu
GPG key:   www.unc.edu/~crimsun/pubkey.gpg.asc
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