On Jun 27, 2011, at 19:00, David Miller <da...@davemloft.net> wrote:
> V8 can only reorder stores, that's why it only has a 'stbar' > instruction. I'm not so sure I agree with trying to paper over the > fact that someone has compiled code for v8 that's going to run on a v9 > cpu. That's not the issue. While it is true that all stores will be submitted in order , this does not guarantee store-load consistency. In particular on a multiprocessor, each individual processor has it's own store buffers and cannot see what is in the other CPUs store buffet. In the end all stores will be committed to memory in a sequential order, but that is not sufficient. The use of a load-store instruction is needed to achieve a full barrier. The SPARC architecture manuals describe this in detail. -Geert
