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SubjectRe: [PATCH 08 of 11] anon-vma-rwsem


On Thu, 8 May 2008, Andrea Arcangeli wrote:
>
> Unfortunately the lock you're talking about would be:
>
> static spinlock_t global_lock = ...
>
> There's no way to make it more granular.

Right. So what?

It's still about a million times faster than what the code does now.

You comment about "great smp scalability optimization" just shows that
you're a moron. It is no such thing. The fact is, it's a horrible
pessimization, since even SMP will be *SLOWER*. It will just be "less
slower" when you have a million CPU's and they all try to do this at the
same time (which probably never ever happens).

In other words, "scalability" is totally meaningless. The only thing that
matters is *performance*. If the "scalable" version performs WORSE, then
it is simply worse. Not better. End of story.

> mmu_notifier_register can take ages. No problem.

So what you're saying is that performance doesn't matter?

So why do you do the ugly crazy hundred-line implementation, when a simple
two-liner would do equally well?

Your arguments are crap.

Anyway, discussion over. This code doesn't get merged. It doesn't get
merged before 2.6.26, and it doesn't get merged _after_ either.

Rewrite the code, or not. I don't care. I'll very happily not merge crap
for the rest of my life.

Linus


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