4.11.7 Memory Barrier
Format:
MB | !Memory format |
Operation:
{Guarantee that all subsequent loads or stores will not access memory until after all previous loads and stores have accessed memory, as observed by other processors.}
Exceptions:
None
Instruction mnemonics:
MB | Memory Barrier |
Qualifiers:
None
Description:
The use of the Memory Barrier (MB) instruction is required only in multiprocessor systems.
In the absence of an MB instruction, loads and stores to different physical locations are allowed to complete out of order on the issuing processor as observed by other processors. The MB instruction allows memory accesses to be serialized on the issuing processor as observed by other processors. See Chapter 5 for details on using the MB instruction to serialize these accesses. Chapter 5 also details coordinating memory accesses across processors.
Note that MB ensures serialization only; it does not necessarily accelerate the progress of memory operations.
