Re: [boost] Re: shifted_ptr<> w/ lock mechanism

From: Peter Dimov (pdimov_at_[hidden])
Date: 2003-01-30 11:12:05

From: "Greg Colvin" <Gregory.Colvin_at_[hidden]>
> At 06:23 AM 1/30/2003, Peter Dimov wrote:
> >
> >To be fair, a factor of two improvement cannot just be shrugged off. But
one
> >point to keep in mind is that
> >
> >shared_ptr<X> px(new X);
> >
> >performs two allocations. We can optimize the count allocation until
we're
> >blue in the face but in a real project the whole expression will probably
> >remain a bottleneck; so it's likely that X will acquire a class-specific
> >operator new. And a X with a class-specific new can no longer be used
with
> >shifted_ptr.
>
> I read a paper yesterday from the latest OOPSLA proceedings
> that argued that a class-specific new is almost never a win
> compared to a high-quality general purpose allocator like
> LEA.

This is the argument I've been using every time the question of adding an
optimized count allocator to shared_ptr came up.