Storing KV cache in different memory tiers (HBM, DDR, Flash) involves trade-offs between retrieval cost, storage cost, and hold time. Optimizing involves balancing these factors, with faster tiers like HBM being more expensive per byte but quicker to access, while slower tiers like DDR or Flash are cheaper but have longer retrieval times.

Impact: High. Strategic use of memory tiers is essential for managing the vast memory requirements of LLMs, directly impacting operational costs and inference speed.

In the source video, this keypoint occurs from 01:48:52 to 01:51:56.

Sources in support: Dwarkesh Patel (Host)