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Subject: Re: [boost] Final benchmark graphs for Colony vs std:: containers now available
From: Soul Studios (matt_at_[hidden])
Date: 2016-05-03 05:01:52

> I think that too much information is missing from the benchmark setup which
> makes the results hard to interpret (see below for some of my questions). A
> good rule of thumb for how much information to include when describing the
> setup of a benchmark is that anybody should, based solely on the
> information provided, be able to re-implement the benchmarks and get the
> same (or very similar) results.
>> The first test measures time to insert N elements into a given container,
> the second measures the time taken to erase 25% of those same elements from
> the container, and the third test measures iteration performance after the
> second test has taken place.
>> Note: because plf::colony is an unordered container and subsequently we
> are not concerned about insert order, push_front has been used with
> std::list instead of push_back, in order to provide a fair performance
> comparison.
> Are you using "push_back"/ "insert(end, N, T())" on vector and deque?
> Reserving memory upfront? Is the final size greater than the capacity
> before the insertion?
> For example if the containers have initially zero size and capacity prior
> to the insertion I cannot understand how anything can be faster than
> "std::vector::vector(N, T())". If the initial capacity is larger than the
> container size after the insertion I cannot understand how anything can be
> faster than "std::vector::insert(end, N, T())". Both of these cases are
> very relevant to the game development application you mention since there
> one typically has an upper bound of the number of elements within a
> container (like maximum number of entities).
>> Erase Performance
> The curve for vector and deque looks like O(N^2): are you using
> erase-remove-if?

Hi Gonzalo, I take your points, but the source code for the tests is
listed on the site:

You can look there if you have further questions.
Regards vector insertion I think you need to check your assumptions
there. It is not a fast insertor due to the fact that it reallocates to
a new memory block upon expansion past capacity. Deque does not do this.
Nor does colony.
Regards insertion, it is all the fastest method available to that class,
so push_back for most, push_front for list. As noted at the top of the
benchmarks, "I have not included results involving 'reserve()' functions
as the differences to overall insertion performance were not adequate.".
This is true, and what's also true is that I find reserve irrelevant. If
you know the size you need, use an array, that's my philosophy.

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