shared memory

A market-data ring in /dev/shm now has identical copies on other hosts, same sequence numbers, same order: 30 µs across a LAN by multicast, 51.7 ms p99 across the Pacific.

An agent taking over acts on a fact someone else wrote. Overwriting memory hands back a stale answer with nothing on it that says so.

The hand-off between a market-data reader and a strategy loop is one of the few latencies in a trading process under our control. How we built a lock-free channel for it, what broke on a 128-core ARM box, and where the assembly landed.