From: Geert Bosch <bo...@adacore.com> Date: Mon, 27 Jun 2011 22:21:47 -0400
> On Jun 27, 2011, at 19:53, David Miller wrote: > >> Adding a ldstub here is going to be really expensive, on UltraSparc >> that can be 36+ cycles even on a cache hit. > > Yes, synchronization in multi-CPU systems is expensive. > If it's really cheap, you're probably doing something wrong. First, I fundamentally disagree with this assertion. The reason proper memory barriers exist is so that you don't need nonsense like these proposed atomics to get proper memory operation ordering. A proper membar on your v9 test system is orders of magnitude cheaper than this stbar+ldstub business. You then go on to speak about LEON, does LEON implement PSO?
