Re: Linux 2.6.7-rc1

From: Jeff Garzik
Date: Sun May 23 2004 - 17:22:45 EST


William Lee Irwin III wrote:
William Lee Irwin III wrote:

I wouldn't qualify either of the major VM patch series merged as
rewrites. I saw:
(1) move unmapping function/helpers to different algorithm to save space
(2) NUMA API and support functions


On Sun, May 23, 2004 at 05:30:55PM -0400, Jeff Garzik wrote:

You missed the pte chains going away, a fundamental change in the way reverse mapping is done?


(1) describes that in more detail than "pte_chains going away". It's
just a search algorithm. For anonymous pages, anon_vma just strobes
offsets into vma inheritance chains, and anonmm just strobes vaddrs in
all forks between execs, for file-backed memory they both use ->i_mmap.
Yes, they can both be summarized in the same sentence. The scope of the
changes are very limited and the presentation of them is a very clearly
documented and incremental series of small changes.


You're getting lost in the details... the scope of the anonvma change is _everybody_. If you accept the premise that we are in a _stable_ kernel series, the core goal should be stability. Non-trivial VM changes like this do not enhance stability in the short term, even if they are a good idea in the long run. It's the whole idea behind minimizing changes and breakage in a stable series.

You've got all the major Linux vendors preparing (or releasing) 2.6.x-based product and IMO the 2.6 kernel is still a moving target, with non-trivial behavior (and sometimes API) changes every couple of kernel versions.

Jeff


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