On Thu, Oct 01, 2015 at 07:03:01PM +0100, Paul E. McKenney wrote: > On Thu, Oct 01, 2015 at 07:13:04PM +0200, Peter Zijlstra wrote: > > On Thu, Oct 01, 2015 at 08:09:09AM -0700, Paul E. McKenney wrote: > > > On Thu, Oct 01, 2015 at 02:24:40PM +0200, Peter Zijlstra wrote: > > > > > > I must say I'm somewhat surprised by this level of relaxation, I had > > > > expected to only loose SMP barriers, not the program order ones. > > > > > > > > Is there a good argument for this? > > > > > > Yes, when we say "relaxed", we really mean relaxed. ;-) > > > > > > Both the CPU and the compiler are allowed to reorder around relaxed > > > operations. > > > > Is this documented somewhere, because I completely missed this part. > > Well, yes, these need to be added to the documentation. I am assuming > that Will is looking to have the same effect as C11 memory_order_relaxed, > which is relaxed in this sense. If he has something else in mind, > he needs to tell us what it is and why. ;-)
I was treating them purely as being single-copy atomic and not providing any memory ordering guarantees (much like the non *_return atomic operations that we already have). I think this lines up with C11, minus the bits about data races which we don't call out anyway. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
