[PATCH] Change atomic operations to use fences for memory barriers

[Scott Long]

John Baldwin wrote:

> The patch below changes the atomic operations on amd64 to use the cheaper 
> fence instructions for memory barriers.  I'd like people to test it to see if 
> 1) it breaks things or not, and 2) if it impacts performance either in a good 
> way or a bad way.  For this last I'm curious about both UP and SMP as my 
> initial guess is that it will help on UP but might hurt on SMP.
> 

I think you forgot the patch.

Scott