Re: [Xen-devel] [PATCH v2 6/6] x86/time: relax barriers

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 03/08/16 14:04, Jan Beulich wrote:
> On x86 there's no need for full barriers in loops waiting for some
> memory location to change. Nor do we need full barriers between two
> reads and two writes - SMP ones fully suffice (and I actually think
> they could in fact be dropped, since atomic_*() operations should
> already provide enough ordering).

Missing a SoB,

Which "ones" are you referring to?  atomic_*() is only ordered with
respect to the atomic_t used.

Overall, I think the change is correct, so Reviewed-by: Andrew Cooper
<andrew.cooper3@xxxxxxxxxx>

There are definitely more mis-uses of mandatory barriers in Xen,
although I haven't done a full audit yet.

~Andrew

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