By: Howard Chu (hyc.delete@this.symas.com), August 28, 2014 9:17 pm
Room: Moderated Discussions
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.
Pretty good comparison of x86, PPC, and ARM here http://preshing.com/20140709/the-purpose-of-memory_order_consume-in-cpp11/
> 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.
Pretty good comparison of x86, PPC, and ARM here http://preshing.com/20140709/the-purpose-of-memory_order_consume-in-cpp11/