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Date: Wed, 19 Jun 2013 16:36:24 +0100
From: Andrew Haley <aph@redhat.com>
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Subject: Re: [Qemu-devel] Java volatile vs. C11 seq_cst (was Re: [PATCH v2
 1/2] add a header file for atomic operations)
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Torvald Riegel <triegel@redhat.com>, qemu-devel@nongnu.org, Liu Ping Fan <qemulist@gmail.com>, Anthony Liguori <anthony@codemonkey.ws>, "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>, Richard Henderson <rth@twiddle.net>

On 06/19/2013 10:30 AM, Paolo Bonzini wrote:
> Il 18/06/2013 19:38, Andrew Haley ha scritto:
>>>> Or is Java volatile somewhere between acq_rel and seq_cst, as the last
>>>> paragraph of
>>>> http://www.cs.umd.edu/~pugh/java/memoryModel/jsr-133-faq.html#volatile
>>>> seems to suggest?
>> As far as I know, the Java semantics are acq/rel.  I can't see anything
>> there that suggests otherwise.  If we'd wanted to know for certain we
>> should have CC'd Doug lea.
> 
> acq/rel wouldn't have a full store-load barrier between a volatile store
> and a volatile load.

Ahhh, okay.  I had to check the C++11 spec to see the difference.  I'm
so deep into the Java world that I hadn't noticed that C++11 was any
different.

Andrew.