Re: [boost] [Block Pointer] Up to 600% faster than Shared Pointer

Subject: Re: [boost] [Block Pointer] Up to 600% faster than Shared Pointer
From: Glen Fernandes (glen.fernandes_at_[hidden])
Date: 2016-03-12 13:06:56

On Sat, Mar 12, 2016 at 12:37 PM, Phil Bouchard  wrote:
> On 03/11/2016 11:12 PM, Glen Fernandes wrote:
>>
>> Hi Phil,
>>
>> What exactly are you measuring here? The time taken to construct an
>> std::auto_ptr<T>/std::shared_ptr<T>/block_ptr<T> inclusive of the time
>> taken for ::operator new(std::size_t) and inclusive of the
>> value-initialization T::T() ?
>
>
> Yes but it also calls ::operator delete(void *) and T::~T().
>
> If I don't use fastblock<>() then it's a simple 150% speedup compared to
> shared_ptr<>:
>
> new:
> auto_ptr:                   22279670 ns
> shared_ptr:                 47428316 ns
> block_ptr:                  31287440 ns
>
>
> My point with fastblock<>() is that it can be use very easily because it is
> already integrated.
>

Since everyone prefers make_shared<T>(args...) when possible instead
of shared_ptr<T>(new T(args...)), I'm not sure that the benchmark of
the latter is very useful.

Rather, given that the preferred use of shared_ptr<T> is with
make_shared() or allocate_shared(), I think you should at least
include that benchmark in this list.

Otherwise you're essentially measuring the cost of 2 ::operator
new(std::size_T) calls (that most people wouldn't write) instead of
the 1 ::operator new(std::size_t) call (that most people would write).

You might as well start replacing auto_ptr with unique_ptr, just to
honor the fact that the former is deprecated. :-)

Glen