u/ANDRVV_

I’m looking for guidance on designing or choosing a high-performance hashmap with the following characteristics:

• Key: 64-bit integer
• Value: 64-bit integer
• Cache line: 128 bytes
• Goal: Accessing a key should automatically bring the corresponding value into cache (implicit prefetching)
• Performance: Extremely low latency, minimal cache misses

I know that some C++ libraries like flat_hash_map or robin_hood::unordered_map achieve this by storing key/value pairs contiguously in memory and using open addressing instead of chaining.

Questions:

• What is the most cache-friendly hashmap design for 64-bit key/value pairs?
• Are there alternatives to open addressing that achieve similar cache performance?
• Any practical advice or references for hashmaps optimized for 128B cache lines?

Looking for insights from anyone who has built or benchmarked ultra-fast hashmaps with minimal cache misses. Thanks!