Re: Intel Memory Ordering White Paper

Nick Piggin
2007-09-08T08:15:51Z

On Sunday 09 September 2007 03:48, Nick Piggin wrote:

> There is some suggestion in the source code that non-temporal stores
> (movntq) are weakly ordered. But AFAIKS from the documents, it is ordered
> when operating on wb memory. What's the situation there?

Sorry, it looks from the AMD document like nontemporal stores to wb
memory can go out of order. It is a bit hard to decipher what the types
mean.

If this is the case, we can either retain the sfence in smp_wmb(), or noop
it, and put explicit sfences around any place that performs nontemporal
stores...

Anyway, the lfence should be able to go away without so much trouble.