On Tue, Feb 04, 2014 at 10:58:40AM -0800, Linus Torvalds wrote: > On Tue, Feb 4, 2014 at 10:41 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > Still doesn't make sense, because if we need the first sync to stop > > writes from being re-ordered with the ll-sc, we also need the second > > sync to avoid the same. > > Presumably octeon doesn't do speculative writes, only *buffered* writes. Speculative writes are bad.. :-) > So writes move down, not up. Right, but the ll-sc store might move down over a later store. Say because the ll-sc needs to first get exclusive ownership of the cacheline where the later store would be to an already owned line.
