Multiprocessors and Thread-Level Parallelism Models of Memory Consistency “ I'm radically increasing Sun's focus on storage today” Sun President Jonathan Schwartz (Oct, 2007)

What behavior should we expect?

Sequential consistency model Data-race-free programs Synchronization mechanism are extremely tricky The programmer's view

Sequential consistency model

Data-race-free programs

Synchronization mechanism are extremely tricky

W->R: total store ordering / processor consistency W->W: partial store order R->W / R->R: weak ordering, PowerPC, release consistency Relaxed Consistency Models

W->R: total store ordering / processor consistency

W->W: partial store order

R->W / R->R: weak ordering, PowerPC,

release consistency

Thank you! Author: Prof. Sergio Takeo, Marcelo Arbore. Bibliography: Patterson, D. A.; Hennessy, J. L. Computer Architecture: A quantitative Approach, 4 th Ed. Morgan Kaufmann Publishers. “ I'm radically increasing Sun's focus on storage today” Sun President Jonathan Schwartz (Oct, 2007)