It is difficult to runtime optimize away the difference between a CPU and GPU

Article: Introduction to OpenCL
By: anon (anon.delete@this.anon.com), December 12, 2010 4:24 pm
Room: Moderated Discussions
hobold (hobold@vectorizer.org) on 12/12/10 wrote:
---------------------------
>Mark Roulo (nothanks@xxx.com) on 12/12/10 wrote:
>---------------------------
>[...]
>> Or are you more optimistic than I am?
>>
>Slightly more optimistic.
>
>An illustrative analogy: GMP (an open source bignum library) isn't really parameterized
>the way I described, but it does contain very different algorithms for some of its
>functions. Wide integer multiply, for instance, has implementations for various
>relative speeds of multiply vs add machine operations, or implementations using
>the FPU, or hybrids that use both integer and FP multiplier hardware. I think there
>is even a SIMD variant. On a higher level, GMP can do very large multiplies by the
>schoolbook algorithm, or based on some recurrence with lower than quadratic complexity,
>or based on integer FFT in logarithmic time.

Don't you mean linearithmic?


>All of the different low level algorithms were originally devised for different
>machines. Every single one is basically unportable, because they are implemented in the respective assembly language.
>
>If they were all implemented in a common language, it would suddenly be practical
>to check which works best for some new hardware architecture. That best candidate
>might be nowhere near a specifically tailored variant for the new machine, but it
>would be a much better starting point than some plain reference implementation.
>
>So yes, we'll keep writing special code for each and every machine. But we'll have
>a much easier time bringing something up on a new kind of machine. And the very
>first version will be not nearly as bad as first versions used to be. OpenCL is
>not fairy dust. But it is an expert tool that IMHO will lead to a real improvement
>of the whole "custom coprocessor" hen-egg problem.
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      It is difficult to runtime optimize away the difference between a CPU and GPUMark Roulo2010/12/10 07:50 PM
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          It is difficult to runtime optimize away the difference between a CPU and GPUMark Roulo2010/12/12 01:20 PM
            It is difficult to runtime optimize away the difference between a CPU and GPUhobold2010/12/12 03:31 PM
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