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Re: [Xen-devel] Linux questions

To: Jan Beulich <jbeulich@xxxxxxxxxx>, Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] Linux questions
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 03 Dec 2007 18:32:24 +0000
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On 3/12/07 11:40, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:

>> rmb() is more powerful than barrier(), not the converse.
> 
> Oh, sorry, I mixed barrier() with mb(). So the proposal would then simply
> be the other way around (the use of locked operations or fence instructions
> on x86 is really unnecessary as long as WC memory or non-temporal stores
> don't need to be taken into consideration).

Then the implementation of rmb() should be equivalent to barrier(). The code
in time-xen.c is implemented to the interface definitions of barrier() and
rmb() -- the former is used just where instruction ordering is important;
the latter where dynamic execution order matters too.

 -- Keir



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