Michael S (already5chosen@yahoo.com) on 8/17/10 wrote:
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>AM (myname4rwt@jee-male.com) on 8/17/10 wrote:
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>>anon (anon@anon.com) on 8/16/10 wrote:
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>>>AM (myname4rwt@jee-male.com) on 8/16/10 wrote:
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>>>>anon (anon@anon.com) on 8/14/10 wrote:
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>>>>>So in summary, nobody has been able to come up with a credible paper proving these
>>>>>fantastic 100x performance gains despite being absolutely certain the claims are real.
>>>>
>>>>In summary, claims that GPUs' perf advantage is limited to 2.5x-5x are complete
>>>>and utter BS,
>>>
>>>AM the claim, actually, is coming from the 100x-1000x people. People here are doubting
>>>that claim because of the numbers involved, but it is not up to them to disprove
>>
>>As a matter of fact, some people here (to be precise, Mark Roulo) asserted that
>>the "real" perf advantage of GPUs over CPUs is 2.5x-5x. Hence my suggestion to him
>>(and David Kanter wrt his own statements) to show how can it possibly be true with
>>a selection of papers as small as 10. Haven't seen anyone of them in the thread since.
>
>I'd like to hear what is your own claim?
>Say, on CPU side i5-760 (4 cores, 2.8 GHz, 8MB L3, no HT, official price=$205),
>multithreaded , SIMD-optimized (not by compiler).

If we allow hand optimization for the CPU, it's obvious that the same should apply to the GPU side. Or rely on compiler in both cases.

>On GPU side best NVidea can offer under $250 (official price, not random internet link).

I wonder what you mean by the official price. AFAIK Nvidia doesn't have some kind of publicly available price list; I think all they do is [sometime] quote target prices for complete products in PRs at the time of release, but needless to say, they change over time.

Besides, LGA 1156 is a cost adder that should be taken into account as well (after all, I agreed with correction for CPU price). Which is $30-$40 as of today, cheap vs cheap.

>Calculation should not take advantage of texture interpolation capabilities (using
>texture cache is, not only allowed but highly desireble) of GPU since, first, it's
>extremely rare in non-3D-rendering code and as such non-representative, second,
>when it happens everybody, including David Kanter and Mark Roulo probably agree that >50x speedup is possible.
>So what speedup do you expect under conditions like above?

Why are you saying interpolation is extremely rare? Whenever we solve numerically a problem which simulates something by representing the reality in discretized form, we can't do without interpolation as long as we want our functions to be at least C0-continuous.

Besides, making good use of texture-interpolation hw was specifically emphasized in one of the papers Intel selected to "debunk" the "myth", but all they did is take some other Monte-Carlo code instead for comparison.

As for your questions re. my claim/expectation,
1) I joined when I saw the comment by Kanter which seems to not be supported with any research/work whatsoever;
2) if we are to take a closer look at i5-760 vs GPU, then we need to clear possible disagreements first anyway (hence my comments above);
3) so far the only article which was clearly shown to be totally misleading is the one by Lee et al.

http://portal.acm.org/citation.cfm?id=1816021&coll=GUIDE&dl=GUIDE&CFID=11111111&CFTOKEN=2222222&ret=1

"Debunking the 100X GPU vs. CPU myth: an evaluation of throughput computing on CPU and GPU"