[boost] Re: Re: Re: problem with shared_ptr

From: Philippe A. Bouchard (philippeb_at_[hidden])
Date: 2003-11-17 19:07:15

Hurd, Matthew wrote:

[...]

> That link seems to suggest it is good for Windows Server 2003 only...
> Is that the case?
>
> InterlockedIncrement suggests it supports
> ___________
>
> Client: Included in Windows  XP, Windows  2000 Professional, Windows
> NT
> Workstation, Windows  Me, Windows  98, and Windows  95.
> Server: Included in Windows Server  2003, Windows  2000 Server, and
> Windows  NT Server.
> ___________

Actually InterlockedIncrementAcquire works only on Windows 2003 Server but
InterlockedIncrement works on every Windows platform:
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/bas
e/interlockedincrement.asp

> For win32 the fastest approach I've found is to turn on the using
> intrinsics optimization for win32... though your mileage may vary.
> Also
> be warned I've found a roughly 3 to 1 difference between AMD and Intel
> P4s on this because of the processor differences.

Interesting...  Intel is usually faster for those memory-access operations.

[...]

> Then perhaps something long the lines of this:
>
> class atomic_op
> {
> public:
>   template< typename word_size_type>
>   static word_size_type inc(word_size_type& v)
>     {
>        assert(sizeof(word_size_type) == sizeof(LONG));
>        return InterlockedIncrement (reinterpret_cast< LONG volatile
> *>( &v ) );
>     }
>
> et cetera...
>
>
> At the end of the day you only get tens of millions of increments a
> second for multithreaded code versus some billions per second for
> single
> thread increments using ++ ;-)

The interesting part is to speed up existing code with minimal dependencies,
knowing it cannot be faster.  I am looking forward for eventual benchmarks
against Hans-Boehm's garbage collectors ;)  To be honest with you, working
on this full-time...  I would implement my "real-time" collector to get rid
instantaneously of cyclic references and add atomic reference count
operations immediately.

Regards.

Philippe