The first installment of this series was an overview of memory barriers, why they are needed in SMP kernels and how the Linux kernel handles them [August 2005]. This installment gives an overview of how several of the more popular CPUs—Alpha, AMD64, IA64, PA-RISC, POWER, SPARC, x86 and zSeries, otherwise known as IBM mainframe—implement memory barriers. Table 1 is reproduced here from the first in