anon (anon.delete@this.anon.com) on August 17, 2014 3:40 am wrote:
> Aaron Spink (aaronspink.delete@this.notearthlink.net) on August 17, 2014 12:42 am wrote:
> > anon (anon.delete@this.anon.com) on August 17, 2014 12:10 am wrote:
> > > I'd like to see actual evidence of this. Of course we've
> > > all seen graphs showing the opposite -- that release
> > > consistency (weak ordering with release barriers) is more performant than strong and processor ordering.
> > >
> > Most of the evidence is anecdotal in nature. Some is this is because processors that are strongly ordered
> > tend to spend some extra hardware resources to increase
> > performance (most x86), second because the programmers
> > tend to be extra cautious on weakly ordered architectures because they've been burned too much.
> >
> > > On the other hand, those have tended to be on academic papers, and the most recent one I've seen
> > > is quite old. So I don't put a lot of stock in those, for modern CPUs and real applications.
> > >
> > As I said, this tends to be one of those areas where theory and practice
> > don't exactly mesh. Academic papers tend to me more theory.
>
> Right, but anecdotes and practice are notoriously unreliable as well.
> Even from experts, with no offense intended to you or Linus.

I'm fully aware of the irony in saying this, by the way, but I'm not setting out to "prove" you wrong or say that weakly ordered are faster than strongly. Just that, with the background of the data we do have, it would be interesting to get some measurements or kinds of data showing where stronger ordering is a performance advantage.