From: Rob Landley <rob@landley.net>
To: larmbr <nasa4836@gmail.com>
Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com,
dhowells@redhat.com, nasa4836@gmail.com
Subject: Re: [PATCH] Documentation/memory-barriers: fix a error that mistakes a CPU notion in Section Transitivity
Date: Fri, 30 Aug 2013 23:16:26 -0500 [thread overview]
Message-ID: <1377922586.2737.149@driftwood> (raw)
In-Reply-To: <20130827103422.GA17355@larmbr-lcx> (from nasa4836@gmail.com on Tue Aug 27 05:34:22 2013)
On 08/27/2013 05:34:22 AM, larmbr wrote:
> The memory-barriers document may has a error in Section TRANSITIVITY.
>
> For transitivity, see a example below, given that
>
> * CPU 2's load from X follows CPU 1's store to X, and
> CPU 2's load from Y preceds CPU 3's store to Y.
I'd prefer somebody with a better understanding of this code review it
before merging. I'm not a memory barrier semantics expert, I can't tell
you if this _is_ a bug.
> +The key point is that CPU 1's storing 1 to X preceds CPU 2's loading
> 1
precedes
> +from X, and CPU 2's loading 0 from Y preceds CPU 3's storing 1 to Y,
precedes
> +which implies a ordering that the general barrier in CPU 2
> guarantees:
an ordering
> +all store and load operations must happen before those after the
> barrier
> +with respect to view of CPU 3, which constrained by a general
> barrier, too.
the view of (or possibly "from the point of view of", the current
phrasing is awkward)
which is constrained
Rob
next prev parent reply other threads:[~2013-08-31 4:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-27 10:34 [PATCH] Documentation/memory-barriers: fix a error that mistakes a CPU notion in Section Transitivity larmbr
2013-08-31 4:16 ` Rob Landley [this message]
2013-08-31 4:34 ` Zhan Jianyu
2013-08-31 15:44 ` Paul E. McKenney
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