COMP 409 Lecture Notes - Lecture 11: Java Virtual Machine, Spinlock, White Paper
22 Mar 2018
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T1 can see: (b, c) = (0, 0), (0, 1), (1, 1), (0, 2), (1, 2), (2, 2) We also get a timeline for y. a = 0 or 3. We are allowed to see (a, b, c) = {0, 3} {all possibilities for (b, c)} Processor consistency: separate timeline for every process. T3 d = x (3) (cid:315) y = 4 (cid:315) (cid:315) = y (2) e = y (4) f = x (1) f sees: Notice this is not coherent! (cid:314) operations on x are not ordered. Note: there also exists examples that are coherent, but not processor consistent. About midterm: open book, covers all material up to and including today. History: implied in the hardware manuals, white paper. I. r. i. w. (independent read, independent write: probably we do not want, not ruled out. P3 ecx = y edx = x eax = 1 ebx = 0 ecx = 1 edx = 0.
