Modern processors have "packet" (nowhere near as complex as ethernet/IP/TCP) based Network On Chip interconnects based with packet routing. Processors suffer f

Modern processors have "packet" (nowhere near as complex as ethernet/IP/TCP) based Network On Chip interconnects based with packet routing. Processors suffer from the classical distributed system style issues just the same, the difference is that as you said they tend to be more reliable and the configuration doesn't change at runtime, but another key aspect is that a lot of latency tradeoffs aren't as lethal due to the short distances within a chip. Accessing data that is kept in the cache of another processor only costs you 100ns at most and a lot of that overhead comes from time spent on the cache coherency protocol. Modern directory based cache coherency protocols are complicated beasts. Each processor core needs to be aware which processors have a copy of the cache line it is about to access, so that it can request exclusive write access to that cache line and mark every single one of those copies dirty upon modification. The way the distributed system problems manifest themselves on the higher levels is that cache coherency by itself doesn't get you correct software automatically. You still have to use synchronization primitives or atomics on the software level, because your registers are essentially stale read replicas. Compare and swap on the processor level is no different than compare and swap on mongodb.