As a native English speaker, I should probably just jump in: Yes, "2x of the speed" would read to me as an awkward way of saying "2x the speed", hence "twice the speed", which means of course "twice as fast", not "twice as slow". The preposition "of" simply does not introduce some fraction. At the very least I just cannot hear any echo of it in my mind.
I recommend reading Steven Pinker's The Stuff of Thought for more on how these quirks reveal how the brain actually works (not just native English speaker ones either). And I was confused by the original statement, thinking that PyPy had just started to deliver on its JIT, instead of the other story, which is really about compatibility. And that's quite cool. - Jim On Tue, Apr 21, 2009 at 8:49 AM, Janzert <[email protected]> wrote: > Carl Friedrich Bolz wrote: > > Niko Matsakis wrote: > >> On Apr 20, 2009, at 8:36 PM, Jacob Hallén wrote: > >> > >>> I think this formulation is a bit confusing. It is not our speed > >>> that is 0.8-2x CPython, it is our performance relative to CPython > >>> that is between 0.8 and 2, with 0.8 meaning that we are faster than > >>> CPython on those benchmarks, and 2 meaning that we need twice the > >>> time to run the benchmark. > >> Maybe I am a bit confused, but I don't see a difference between those > >> two things? > >> > >> i.e., if the speed is 0.8x CPython, to me that means that it runs in > >> 80% of CPython's time (i.e., faster), whereas 2x CPython would be > >> twice as much time. > >> > >> In any case, I agree that the second formulation is phrased more > >> clearly, just curious if my understanding of 0.8x is flawed. > >> > > > > Hi Niko, > > > > FWIW, that's the reasoning we had when we wrote the thing. However, we > > keep having this discussion every time we write something about > > performance, so I guess it's not as clear as you and me think :-). > > > > Carl Friedrich > > I've seen this discussion several times and not only in pypy related > contexts. It seems that the majority of native English speakers (or > possibly it's just American's?) interpret the statement in exactly the > opposite way the majority of non-native speakers do. With "2x of the > speed" being interpreted as two times faster by native speakers and as > taking twice the amount of time by non-native speakers. > > Janzert > > _______________________________________________ > [email protected] > http://codespeak.net/mailman/listinfo/pypy-dev > -- Jim Baker [email protected]
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