Executive Summary
On April 24, 2026, DeepSeek released V4, its fourth-generation large language model, representing a significant leap in efficient AI architecture design. The model introduces a hybrid attention mechanism combining Chunked Shared Attention (CSA) and Hash-based Chunked Attention (HCA), a novel Mixture-of-Experts configuration with 384 experts, and aggressive KV cache compression that enables 1 million token context windows on commodity hardware.
V4-Flash inference cost is 12× lower than V4-Pro at <10% quality loss. The Pro/Flash split is the first credible price-tier split within a single frontier open-weights family — a direct challenge to GPT-4-class pricing floors.
Key Innovations
V4 is not one breakthrough but a stack of eight coordinated architectural decisions, each addressing a specific bottleneck exposed by 2025's inference scaling wall. This report decomposes every one, mapped onto the Roofline model of memory-vs-compute economics.
Multi-Latent Attention (MLA)
7168 → 512 KV compression128× KV cache reduction via low-rank projection. Trades a modest compute injection (up-projection) for massive memory-traffic savings, pushing the attention kernel deep into compute-bound territory.
384-Expert MoE Router
6 shared + 1 routed per tokenExtreme sparsity ratio: only ~3% of parameters active per forward pass. Combined with mHC residual connection to avoid the classic MoE routing collapse under aggressive sparsity.
TileLang · Muon · FP4-Native
Kernel DSL + optimizer + quantA vertically integrated kernel + training stack. TileLang lets researchers hand-fuse attention kernels; Muon replaces AdamW for MoE stability; FP4-native training removes the post-hoc quantization tax.
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The remaining 7 chapters cover the full Architecture Visualization (with an interactive SVG blueprint of both prefill and decoding phases), MLA vs MHA dimension transform (animated), the live Performance Calculator (batch size × context length × expert count), Shocking Conclusions (H100 vs B200 leapfrog math), Thematic Analysis (5 themes with tabbed navigation), the Competitive Landscape matrix (12 models mapped), and the full Roofline Regime Shift analysis.