Re: [GD-General] cross platform 64bit lock free FIFO?

[Jon W. <hp...@mi...>]

More than one question in the same message.

Typically, a lock-free FIFO supports only a single writer and a single 
reader. If that's all you need, then you don't even need the special 
instructions, because the writer will always write the same variable, 
and the reader will always read the other same variable. If your cache 
is not 100% read-after-write coherent, then you may have a temporary 
situation where there's something written that the reader doesn't yet 
see (or vice versa), but on Intel, that can never happen.

If you need multiple readers, or multiple writers, then correct 
lock-free implementation suddenly becomes a *lot* harder.

Cheers,

                / h+


Andras Balogh wrote:
> I've found info on know how to implement a lock free FIFO on 32bit  
> systems, but I've also read that making it work for 64bit systems with the  
> current instruction sets is very difficult and extremely error prone. So I  
> would prefer to use a proven solution, instead of trying to roll my own.  
> On Windows, it's easy, because the Win32 API provides an interlocked  
> SList, that is supposed to work on 64 bit platforms too. But what about  
> other operating systems? Also, AFAIK these new 64bit systems don't really  
> have a 64bit address space, but 40-44? Does this mean, that all these  
> 64bit implementations are doing is only using the top 20 bits for ABA  
> resolution?? I'm confused :)
>