O Simple categorization of relaxed models Relaxation W→R|W→W|R→RW‖ Read Others, Read Own‖ Safety net Order Order Order Write Early Write Early SC[6] IBM370[4] serialization instructions TSO [20] RMW RMW 匚Psop0 ‖RMw, STBAR synchronization RCsc[13,12] release, acquire, nsync, RMW RCpc[13,12] I release, acquire, nsync, RMW Alpha 19 MB. WMB RMO [21] various members PowerPC[7,4]√ SYNC Figure 8: Simple categorization of relaxed models. AV indicates that the corresponding relaxation is allowed by straightforward implementations of the corresponding model. It also indicates that the relaxation can be detected by the programmer(by affecting the results of the program) except for the following cases. The"Read Own Write early?relaxation is not detectable with the SC, wo. alpha, and powerPC models. The "Read Others'Write early" relaxation is possible and detectable with complex implementations of RCsc 2021/2/11 计算机体系结构Simple categorization of relaxed models 2021/2/11 计算机体系结构 10