On Mon, Oct 15, 2007 at 10:09:24AM +0200, Nick Piggin wrote:
I'm not performance-words at all, so I can't help you, sorry. But, I
understand people who care about this, and think there is a popular
conviction barriers and locked instructions are costly, so I'm
surprised there is any "problem" now with finding these gains...
I'm not sure this is the right way to tell it. If there is no
distinction between what is and what could be, how can I believe in
similar Alpha or Itanium stuff? IMHO, these manuals sometimes look
like they describe some real hardware mechanisms, and sometimes they
mention about possible changes and reserved features too. So, when
they don't mention you could think it's a present behavior.
As a matter of fact it's not natural for me at all. I expected the
other direction, and I still doubt programmers' intentions could be
"automatically" predicted good enough, so IMHO, it's not for long.
Of course, it doesn't seem to be any help for linux or bsd
programmers, which still have to think about different architectures.