Subj : Re: RCU+SMR
To   : comp.programming.threads
From : Joe Seigh
Date : Sat Jul 09 2005 10:52 am

Chris Thomasson wrote:
>>Way back, I came up with a scheme where you make the queue a lock-free
>>LIFO stack using compare and swap.  The single reader just grabbed the
>>entire queue using compare and swap, reversed order making it FIFO
>>and worked off of that util it was empty and then repeated the whole
>>process by grabbing the shared LIFO stack again.
> 
> 
> Yep. That works very well. I have used the simple scheme for a while as 
> well. I used an atomic exchange for the consumers:
[...]
> LIFO producers are inherently not affected by aba. On the other hand, LIFO 
> consumers are affected, but only if there is a "compare" type method being 
> used for synchronization. Using an atomic exchange to set the stack anchor 
> to zero can get around aba wrt LIFO lock-free stacks. Was that similar to 
> your initial solution?
> 
> 
Yes.  The null object has special properties.  Remember null is an arbitrary
definition.  It doesn't have to be (void *)0 (except for C++).  You should
be able to make it an arbitrary designated address.  In other words any
designated placeholder object will work as well.


-- 
Joe Seigh

When you get lemons, you make lemonade.
When you get hardware, you make software.

.