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Date: Fri, 15 Jan 2016 22:27:14 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
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        Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [v3,11/41] mips: reuse asm-generic/barrier.h
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On Fri, Jan 15, 2016 at 09:46:12AM -0800, Paul E. McKenney wrote:
> On Fri, Jan 15, 2016 at 10:13:48AM +0100, Peter Zijlstra wrote:

> > And the stuff we're confused about is how best to express the difference
> > and guarantees of these two forms of transitivity and how exactly they
> > interact.
> 
> Hoping my memory-barrier.txt patch helps here...

Yes, that seems a good start. But yesterday you raised the 'fun' point
of two globally ordered sequences connected by a single local link.

And I think I'm still confused on LWSYNC (in the smp_wmb case) when one
of the stores looses a conflict, and if that scenario matters. If it
does, we should inspect the same case for other barriers.