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Subj : Re: full-blown experiential smr-based reference counted pointer impl...
To   : comp.programming.threads
From : Chris Thomasson
Date : Fri Apr 01 2005 12:27 pm

> Yes.  Though with classical RCU the quiesent states aren't so near the 
> critical
> regions and the membars are around the quiesent state itself, so they're 
> not
> near the critical regions either.  But the RCU implementation I did uses
> membars like your example shows.

Yeah. So does mine, I basically have it down to something like this:


// Acquire RCU
1. store 1 into per-thread rcu_quiescent
2. ( acquire barrier )
3. increment per-thread rcu_generation


  //  gc region


// Release RCU
4. ( release barrier )
5. store 0 into per-thread rcu_quiescent


As long as step 3 is made visible before step 5 is made visible, everything 
rocks. Plus, its loop-less and requires fewer memory barriers. Sure seems 
there would be a lot less overhead when protecting the increments of a 
single-word reference count...

.

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