<figo1802@xxxxxxxxx> Message-ID: <589ca54b-4171-4164-b9ba-dc3a5bad6376@xxxxxxxxxxxxxxxxx> Yes, if you have concrete scenarios we can discuss them. "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx> wrote: >On Tue, Nov 26, 2013 at 04:46:54PM -0800, H. Peter Anvin wrote: >> On 11/25/2013 07:16 PM, Paul E. McKenney wrote: >> > >> > My biggest question is the definition of "Memory ordering obeys >causality >> > (memory ordering respects transitive visibility)" in Section 3.2.2 >of >> > the "Intel® 64 and IA-32 Architectures Developer's Manual: Vol. 3A" >> > dated March 2013 from: >> > >> > >http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-3a-part-1-manual.html >> > >> > I am guessing that is orders loads as well as stores, so that a >load >> > is said to be "visible" to some other CPU once that CPU no longer >has >> > the opportunity to affect the return value from the load. Is that >a >> > reasonable interpretation? >> >> The best pointer I can give is the example in section 8.2.3.6 of the >> current SDM (version 048, dated September 2013). It is a bit more >> complex than what you have described above. > >OK, I did see that example. It is similar to the one we are chasing >in this thread, but there are some important differences. But you >did mention that that other example operated as expected on x86, so >we are good for the moment. I was hoping to gain more general >understanding, but I would guess that there will be other examples >to help towards that goal. ;-) > >> > More generally, is the model put forward by Sewell et al. in >"x86-TSO: >> > A Rigorous and Usable Programmer's Model for x86 Multiprocessors" >> > accurate? This is on pages 4 and 5 here: >> > >> > http://www.cl.cam.ac.uk/~pes20/weakmemory/cacm.pdf >> >> I think for Intel to give that one a formal stamp of approval would >take >> some serious analysis. > >I bet!!! > >Hey, I had to ask! ;-) > > Thanx, Paul -- Sent from my mobile phone. Please pardon brevity and lack of formatting. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>