That would be me. I have been offline writing for OLS and did not get
to respond before this.
When we first saw these patches the reaction was a general positive
despite skepticism on the general utility of vmemmmap. The patches
appear to provide an architecture neutral implementation. At that time
s390 was just starting to use vmemmap bringing 2x implementations into
the kernel. Now we have three. Clearly, even if vemmemap was a net
performance loss having only one implementation has to be a good thing
for maintainability/coverage.
Without some benchmarking and some general testing it certainly is
premature to be removing the other memory models, but for sure that was
the original plan. The original assumption that as time went on the
other models would wither on the vine, this has only happened on powerpc
so far.
So I will go and:
1) talk to s390 and find out if they can use this same form, as one
implementation of vmemmap only should be the goal, and
2) take the current patches and try and get some benchmarks for them
against other memory models
Christoph if you could let us know which benchmarks you are seeing gains
with that would be a help.
-apw
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