Saving another 100TB of RAM with math (and Rust)

Good reminder that the cheapest capacity win is sometimes a page of maths. Cloudflare’s Pingora Backend Router was spending up to 6GB per instance on consistent hash rings, so they derived the coefficient of variation and found the last 90,000 of 100,000 hashes per server bought all of 0.7% improvement. Drop the hash count by 90%, shrink a struct from 8 bytes to 6, and that’s 100TB of RAM back across the network.