Re: [PATCH RFC tip/core/rcu] rcu: direct algorithmic SRCUimplementation

[Mathieu Desnoyers]

* Peter Zijlstra (peterz@xxxxxxxxxxxxx) wrote:
> On Thu, 2012-02-16 at 05:50 -0500, Mathieu Desnoyers wrote:
> > > Ah, so something like this?
> > > 
> > >       ACCESS_ONCE(this_cpu_ptr(sp->per_cpu_ref)->c[idx]) += 
> > >               SRCU_USAGE_COUNT + 1;
> > > 
> > > Now that you mention it, this does look nicer, applied here and to
> > > srcu_read_unlock().
> > 
> > I think Peter refers to __this_cpu_add(). 
> 
> I'm not sure that implies the ACCESS_ONCE() thing
> 

Fair point. The "generic" fallback for this_cpu_add does not imply the
ACCESS_ONCE() semantic AFAIK. I don't know if there would be a clean way
to get both without duplicating these operations needlessly.

Thanks,

Mathieu


-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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