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SubjectRe: [PATCH v5 8/9] x86-64: Emulate legacy vsyscalls

* pageexec@freemail.hu <pageexec@freemail.hu> wrote:

> > A fastpath is defined by optimization considerations applied to a
> > codepath (the priority it gets compared to other codepaths),
> > *not* by its absolute performance.
>
> we're not talking about random arbitrarily defined paths here but
> the impact of putting well predicted branches into the pf handler
> vs. int xx (are you perhaps confused by 'fast path' vs.
> 'fastpath'?).

So please educate me, what is the difference between 'fast path'
versus 'fastpath', as used by kernel developers, beyond the space?

> that impact only matters if it's measurable. you have yet to show
> that it is. and all this sillyness is for a hypothetical situation
> since those conditional branches don't even need to be in the
> general page fault processing paths.

Is this some sort of sick joke?

Do you *really* claim that the number of instructions executed in a
fastpath do not matter and that our years-long effort to shave off an
instruction here and there from the x86 do_page_fault() code were
meaningless and that we can add branches with zero cost?

Thanks,

Ingo


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