Re: [boost] [Block Pointer] benchmark

Subject: Re: [boost] [Block Pointer] benchmark
From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2011-05-25 16:39:12

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On Wednesday, May 25, 2011, Phil Bouchard wrote:
> 
> So we have shared_ptr being initialized with an object created by
> operator new.  shared_ptr will then allocate another reference counter.
>   2 allocations is faster than the make_shared counterpart so yes
> copying a pointer is slower than 2 heap allocations.

What version of boost are you referring to?  make_shared used to be slow due 
to it doing a lot of unnecessary copying of the storage area for the 
pointee, but that should have been fixed probably a couple years back now.  
Copying a shared_ptr is fairly slow due to the atomic reference counting, 
but I would expect a compiler to be able to elide the copy of the 
make_shared return value.

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