Subject: Re: [boost] [Block Pointer] Up to 600% faster than Shared Pointer
From: Phil Bouchard (philippeb8_at_[hidden])
Date: 2016-03-12 13:40:49
On 03/12/2016 01:06 PM, Glen Fernandes wrote:
> 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
>> 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).
Good point. If I compare make_shared<>() with new block<>() then the
speeds are almost the same:
auto_ptr: 25614443 ns
shared_ptr: 26603216 ns <-
auto_ptr: 23529804 ns
shared_ptr: 49876800 ns
block_ptr: 29975876 ns <-
If I compare make_shared<>() with new fastblock<>() I have a 300% speedup:
auto_ptr: 25672479 ns
shared_ptr: 27077638 ns <-
auto_ptr: 22647604 ns
shared_ptr: 53317702 ns
block_ptr: 8911600 ns <-
> You might as well start replacing auto_ptr with unique_ptr, just to
> honor the fact that the former is deprecated. :-)
I tried to quickly but for some reason auto_ptr<> is still the one
dangling around in my GCC API.
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