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SubjectRe: [rfc] x86: optimise page fault path a little


On Fri, 14 Nov 2008, Nick Piggin wrote:
>
> True, but is it any better to jam them all into a 300 line function
> with gotos?

That wasn't what I was saying.

Theere are two "good" cases:

- don't mess with things.

This is good. Stability is good.

- Clearly improve things.

This is great.

And I'll happily do either of the above.

Your patch had some improvement, but it had some clear not-so-improved
parts. That makes it INFERIOR to just leaving things well alone.

The thing is, I'm not very much interested in just a micro-optimization
that seems to be all about just gcc code generation. Long-term, that's
just bad.

But if it's a clear and undeniable _cleanup_, then long-term, it's
actually a win. If it also happens to fix some gcc stack allocation issues
etc, then that is just gravy.

See my point? Cleanup is good. But it had better _be_ a cleanup. Random
micro-optimization is not so good, especially not if it them makes the
code do things that good code simply shouldn't be doing.

As it is, I don't think your patch is appropriate to be merged.

Linus


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