On Saturday 08 September 2007 20:19, Andi Kleen wrote: > On Friday 07 September 2007 21:57:35 Nick Piggin wrote: > > > > Anyway, the lfence should be able to go away without so much trouble. > > > > > > You mean sfence? lfence in rmb is definitely needed. > > > > I mean lfence in smp_rmb(). > > One point of rmb is to stop speculative loads and I don't think we > can get that without lfence.
smp_rmb() should not need to do anything because loads are done in order anyway. Both AMD and Intel have committed to this now. The important point is that they *appear* to be done in order. AFAIK, the CPUs can still do speculative and out of order loads, but throw out the results if they could be wrong. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/