30 ms·
The usual way that barriers were implemented was to simply stall the CPU pipeline. So yes, they do indeed have blocking semantics. IIRC mfence still does stall
by gpderetta 2y ago
The usual way that barriers were implemented was to simply stall the CPU pipeline. So yes, they do indeed have blocking semantics. IIRC mfence still does stall the pipeline on x86, but I think the CPU is a bit smarter for locked instructions.