Messages in this thread | | | Date | Tue, 7 Jun 2011 10:30:59 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v5 8/9] x86-64: Emulate legacy vsyscalls |
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* 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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