MFENCE
mfence is a memory fence instruction used in the x86 architecture. It acts as a full memory barrier, enforcing ordering between memory operations so that all memory accesses issued before the fence become globally visible before any accesses issued after the fence. In practice, mfence prevents reordering of both loads and stores across the barrier and ensures that previous memory effects are completed before subsequent ones are allowed to proceed.
In x86 processors, the mfence instruction complements the processor’s memory model to provide a stronger ordering
mfence can be issued directly as an assembly instruction or through compiler-provided intrinsics and built-ins in
Cross-architecture, similar barriers exist but under different names and semantics—for example, certain ARM barriers (dmb) and