For low latency messaging like this you'd typically want to avoid cross socket data transfers. However, IIRC cacheline snooping across sockets is a bit quicker

For low latency messaging like this you'd typically want to avoid cross socket data transfers. However, IIRC cacheline snooping across sockets is a bit quicker (Intel QPI at least) than remote dram access so if the lines stay in cache the communication may be under 100ns. Also, depending on access pattern, hardware prefetch may hide some of the latency.