[Xen-devel] Re: Linux questions

[Andi Kleen <andi@xxxxxxxxxxxxxx>]

Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> writes:

> On 4/12/07 10:23, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
>
>> I have to disagree: At least the uses of barrier() in monotonic_clock() 
>> appear
>> to be in places where in reality (and from a theoretical standpoint) rmb()
>> ought to be used.
>
> We're sync'ing against concurrent updates of a this_cpu variable. We can
> only race updates in a local ISR, and hence barrier() suffices.

Not if you use RDTSC inside the loop.

-Andi

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