Re: [boost] [spinlock] Spin on volatile read, NUMA fairness?

Subject: Re: [boost] [spinlock] Spin on volatile read, NUMA fairness?
From: Niall Douglas (s_sourceforge_at_[hidden])
Date: 2014-12-04 08:21:55

On 3 Dec 2014 at 23:52, Stephan T. Lavavej wrote:

> [Niall Douglas]
> > I think the Intel paper was referring to MSVC only, which is an 
> > unusual compiler in that its atomics all turn into InterlockedXXX 
> > functions irrespective of what you ask for. In other words, all 
> > seq_cst.
> 
> Absolutely untrue for VC-ARM. Also untrue for VC 2015 x86/x64, where
> <atomic> avoids Interlocked machinery when an ordinary load/store with a
> compiler barrier will suffice due to the strength of the architecture's
> guarantees. (The versions are blurring together, so I forget when we
> made this change.) 

Which would explain why a volatile read has no difference to an 
atomic consume read, which is an obvious duh on my part. Thanks for 
the catch Stephan.

Niall
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