Re: [Xen-devel] [PATCH] xen/x86: Drop unnecessary barriers

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.01.18 at 15:17, <andrew.cooper3@xxxxxxxxxx> wrote:
> x86's current implementation of wmb() is a compiler barrier.  As a result, the
> only change in this patch is to remove an mfence instruction from
> cpuidle_disable_deep_cstate().
> 
> None of these barriers serve any purpose.  They are not synchronising with
> remote cpus, and their compiler-barrier properties are not needed for
> correctness purposes.
> 
> Furthermore, these wmb()'s specifically do not want to turn into sfence
> instructions in future changes where wmb()'s implementation is corrected.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>



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