1.46 to 1.49× more conversations per H100, bit-identical output. KV Exact stores your KV cache in 0.687 of its original size. The cost is stated plainly: attention runs at about 0.6 to 0.8× speed per step on H100 (measured, 2026-10-10).
Inference is the biggest line on the bill, and the KV cache caps how many conversations each GPU can serve. KV Exact frees about 30% of the memory the cache uses so each H100 holds 1.46 to 1.49× more conversations, with output identical bit for bit. The cost is speed: attention runs at about 0.6 to 0.8× speed per step on H100 (measured, 2026-10-10).
| Per conversation, DeepSeek-V2-Lite | Standard cache | KV Exact |
|---|---|---|
| GPU memory, 32k tokens | 1.02 GB | ~0.71 GB |
| Share of one 80 GB H100 | 1.3% | 0.9% |
| Conversations per H100 at 32k / 64k / 128k | 39 / 19 / 9 | 55 / 27 / 13 |
| Answer quality | reference | bit-identical |
Range across configurations 0.55 to 1.03. You trade some attention speed per step for 1.46 to 1.49× more conversations on the same GPU.
Measured on H100, 2026-10-10, bit-identical output.
| Fleet limited by | Gain | H100s needed | Saving, reserved | Saving, on demand |
|---|---|---|---|---|
| GPU memory (concurrent conversations), estimate | 1.4× | 715 | ~$5.0M | ~$9.0M |
DeepSeek-V2-Lite cache in bf16 is 31,104 bytes per token. Per-GPU figures assume about 40 GB of each H100 is left for cache after the model weights. KV Exact frees about 30% of cache memory including memory-page overhead (measured on one long prompt; more prompts pending) and fits 1.46 to 1.49× the concurrent long-context conversations at the same cache memory on an H100 (measured; first verified at about 1.4× on a consumer GPU). The 1.46 to 1.49× conversation capacity and the 0.6 to 0.8× attention speed were measured on an H100 on 2026-10-10 with bit-identical output; the 1.4× in the fleet estimate is the more conservative figure first verified on a consumer GPU. Reserved H100 capacity at about $2.00 per hour ($17,500 per GPU-year); on-demand at about $3.61 per hour.
Restoring a conversation from CPU memory or SSD, reusing a shared prompt prefix, and handing a request from a prefill server to a decode server all wait on a link. KV Exact moves a third fewer bytes over every one of them, and keeps answers bit-identical.
| Metric | Original | weights.zip | Improvement |
|---|---|---|---|
| Restore from CPU memory over PCIe (consumer GPU) | 1.00× | 1.43× | 43% faster |
| Bytes moved for offload, restore and prefill to decode | 1.00× | 0.68× | 32% less |
| Offload to CPU memory over PCIe (consumer GPU) | 1.00× | 1.35 to 1.43× | up to 43% faster |
| Conversations cached per GB of RAM or SSD | 1.00× | 1.46× | 46% more |
Restore and offload measured on a consumer GPU with a 113 MB conversation cache; data-center GPU timing is pending. In a fleet that spends 10% of GPU time waiting on cache restore or transfer, cutting that wait by 32% frees about 3% of GPU time: about $30M a year on a $1B inference budget. That is an illustration, not a measurement; your share depends on how link-bound your cache traffic is.
| Measure | Result | Status |
|---|---|---|
| Concurrent conversations per H100 at fixed cache memory, DeepSeek-style models | 1.46 to 1.49× | measured on H100, 2026-10-10, bit-identical output |
| Attention speed per step against uncompressed bf16 at the same batch, DeepSeek-style | about 0.6 to 0.8× | measured on H100, 2026-10-10: median 0.63, best later kernel median 0.77, range 0.55 to 1.03 |
| GPU memory freed for the KV cache, including page overhead | about 30% | measured on one long prompt; more prompts pending |
| Model output with the cache restored inside attention, 32k to 128k tokens | bit-identical | measured |
| Cache size on a real standard-attention model (Llama-3.1-8B class), keys and values | 0.686 to 0.687 | measured, 8k-token reference |
| Speed on standard-attention models | pending | not yet tested on real standard-attention caches |
| Measure | Result | Status |
|---|---|---|
| Cache size, bit-exact, held-out data | 0.687 of original | independently verified: real file written and rebuilt bit for bit by a separate decoder |
| Cache size, GPU version | 0.683 of original | independently verified, bit-exact |
| Cache size on GLM-4.7-Flash, same cache style as DeepSeek, no retuning | 0.687 of original | measured, bit-exact |
| Conversation restore from CPU memory over PCIe | 1.43× faster | measured on a consumer GPU (RTX 4060) |
| Conversation offload to CPU memory over PCIe | 1.35 to 1.43× faster | measured on a consumer GPU (RTX 4060) |
| Cached conversations per GB of CPU RAM or SSD | 1.46× | follows from size |
As of October 2026, none of the major open serving stacks (vLLM, SGLang, TensorRT-LLM, LMCache) ships lossless KV compression. Serving Llama? KV Cache stores Llama caches 1.59× smaller, also bit for bit.
All figures are measured on public models (Qwen2.5 0.5B and 1.5B, Llama-3.1 8B and 70B, Pythia-160M, GPT-2 and a 27B FP8 model) on NVIDIA H100 SXM, H200 and RTX 4060 GPUs. Every restore was checked byte for byte against the original. zstd comparisons use zstd level 19 or NVIDIA nvCOMP Zstd on the same files. Dollar figures assume S3 Standard-class storage at about $24 per TB-month and typical cloud egress pricing. Results depend on the model and data type, so the free benchmark measures yours.