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

Subject: Re: [boost] [xint] Third release is ready, requesting preliminary review
From: DE (satan66613_at_[hidden])
Date: 2010-05-03 14:01:19

on 03.05.2010 at 21:37
 Stewart, Robert wrote :

> DE wrote:
>> i suddenly have remebered a rule on optimization: measure,
>> then optimize
>> in other words: find a bottleneck and only then optimize the
>> code causing it

> That's exactly what Chad did.  That's why he added COW.  With the
> addition of move semantics, there's reason to think it shouldn't be needed.

>> in this thread things look the other way around
>> you guys make a guess and ask to change/optimize the code using that
>> guess as the basis
>> sorry, i consider it wrong

> There is nothing wrong with trying to poke holes in a design or
> implementation.  From experience, we know that COW is usually a
> pessimization rather than an optimization in MT code, so it is
> usually avoided altogether for simplicity.  Its need raises red
> flags.  When the tests suggest that the library is truly faster with
> COW, we're a little skeptical and want to understand why.  This is the scientific method in action.

>> in fact it must be like this:
>> - i use it in a <usecase>, i profiled it and found a bottleneck in the
>> following piece of code...
>>
>> otherwise there is a big chance we are wasting each others time making
>> guesses and arguing about implementation details
>> because optimizations born from that may be worthless

> I disagree.  The COW issue will be raised during review.  Chad
> needs to be ready to defend its use then.  Having done so now means
> he can explain it in the docs and avoid such discussions during the review.

i agree with almost all you've just said
however chad not only stated that his cow is faster (a pun intended)
but also provided numbers (test results -- read "the proof")
so that's you who must prove the cow is slower than whatsoever or
misapplied, not chad

-- 
Pavel
P.S.
if you notice a grammar mistake or weird phrasing in my message
please point it out