Re: [boost] [compute] Review

On 2014-12-30 23:41, Kyle Lutz wrote:

On Tue, Dec 30, 2014 at 6:23 PM, John Bytheway wrote:

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On 2014-12-29 02:01, Kyle Lutz wrote:

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On Sun, Dec 28, 2014 at 7:26 PM, John Bytheway wrote:

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- Why does reduce return its result through an OutputIterator?

In order to allow the algorithm to store the result in device memory and avoid a host-device synchronization point (which would be necessary if it simply returned the reduced result).

That makes sense, but seems inconsistent with accumulate, and to a lesser extent the algorithms that return bool (binary_search, equal, etc.) Are they all introducing a synchronization point? What about the ones returning iterators?

Yeah, algorithms like accumulate() which return the resulting value on the host are synchronization points. Others like transform() which return an iterator do not because the returned iterator is not actually the "result" of the operation and can be calculated and returned before the operation is actually complete.

That's true of transform, but not for most algorithms returning an iterator, surely. How would you do this with find, or set_intersection? John