Re: [boost] [xint] Third release is ready, requesting preliminary review

Subject: Re: [boost] [xint] Third release is ready, requesting preliminary review
From: Chad Nelson (chad.thecomfychair_at_[hidden])
Date: 2010-05-02 21:36:10

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On 05/02/2010 07:20 PM, Jeffrey Lee Hellrung, Jr. wrote:

>> I've just posted the results of my testing. As to *why* it's that much
>> faster, I can only provide educated guesses.
> 
> I think it is important to understand what the discrepancy is, because
> it may be that you're not writing your algorithms in a move-aware way,
> producing copies unnecessarily.  This wouldn't surprise me if you wrote
> the original implementations with COW primarily in mind (which I can't
> blame you for).

I did, of course. But with the exception of operator+ and operator-, I
don't see anything that could benefit from additional move-specific
overloads.

>>> So, bottom line:  Give me a real example of an algorithm where COW
>>> gives superior performance to move semantics, and I'll buy into the
>>> COW implementation.
>>
>> I'll give you one better: the actual timings, which you can reproduce
>> yourself if you doubt their accuracy. :-) Just let me know if you want
>> the code I used to come up with them... the rules I read say that I'm
>> not supposed to post any files to this list, so if you want them, I'll
>> need to upload the changes somewhere.
> 
> I'll take a look at the performance testing code when I get a chance,
> but I'm guessing a problem *could* be that you're not maximizing the
> opportunities to moven from or otherwise modify temporaries.

It's possible. Show me a better way and I'll adopt it. I don't think the
operator+ and operator- are going to make a lot of difference to the
results though.
- -- 
Chad Nelson
Oak Circle Software, Inc.
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