Cloudflare frees 100TB of RAM by reengineering its DNS cache in Rust
Cloudflare cut the 1.1.1.1 DNS cache’s memory footprint by more than half—about 100TB across its network—without new hardware by reworking Big Pineapple in Rust. Changes shrank each cache entry from 953 to 420 bytes, replaced growable data structures with fixed-size slices, and stored responses as a single buffer with two-byte offsets and length-prefixed wire-format data. Throughput rose from 625k to 893k inserts/sec, lookups halved latency (828ns to 670ns), and p99 memory per instance fell from 9.3GB to 5.3GB. With over 250 billion DNS entries cached, the savings free RAM for larger caches, boosting hit rates and reducing traffic to authoritative servers; the effort follows a prior Rust rewrite of Cloudflare’s FL2 layer.
