quantcore-ai 0.4.2

Adaptive Memory Runtime for LLMs — compress KV cache 3-7x with vectorized GPU ops, fused compressed attention, and rigorous benchmark suite

QuantCore

Adaptive Memory Runtime for LLMs.

QuantCore compresses the Key-Value cache of transformer models during inference using the TurboQuant algorithm (ICLR 2026). It reduces KV cache memory by 2–6x with dynamic bit switching, memory budgets, and sliding window eviction — enabling longer context windows, cheaper GPU costs, and OOM-free inference.

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When QuantCore Helps

KV cache memory grows linearly with sequence length. At short contexts (< 1K tokens), KV cache is small and model weights dominate memory. QuantCore's impact becomes significant when KV cache is the bottleneck:

Scenario	KV Cache Size	QuantCore Impact
Short chat (< 512 tokens)	Small	Minimal
Long context (2K–8K tokens)	Large	Significant savings
Very long context (8K–32K tokens)	Dominant	Critical — prevents OOM
Multi-user serving (batched)	Multiplied	Major cost reduction

Real Numbers (Llama-3.1-8B, balanced mode)

Context Length	FP16 KV Cache	QuantCore	Saved
1,024 tokens	22 MB	12 MB	10 MB
4,096 tokens	88 MB	47 MB	41 MB
8,192 tokens	176 MB	94 MB	82 MB
16,384 tokens	352 MB	187 MB	165 MB

At 16K context with 8 concurrent users, that's 1.3 GB saved — enough to avoid upgrading from a 16GB to 24GB GPU.

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Quick Start

pip install quantcore-ai

from transformers import AutoModelForCausalLM
from quantcore import optimize_model

model = AutoModelForCausalLM.from_pretrained("meta-llama/Llama-3.1-8B")

# One-line integration
model = optimize_model(model, mode="balanced")

# Use normally — no other changes needed
outputs = model.generate(input_ids, max_new_tokens=1000)

# Check savings at your context length
stats = model.quantcore_stats(seq_len=4096)
print(f"Memory saved: {stats['memory_saved_mb']:.0f} MB")

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Adaptive Runtime (v2)

QuantCore v2 dynamically adjusts compression during inference based on real-time GPU memory pressure.

# Adaptive mode: auto bit-switching + memory budgets + eviction
model = optimize_model(
    model,
    mode="adaptive",
    max_memory="8GB",       # memory budget
    max_cache_len=8192,     # sliding window eviction
)

# The runtime automatically:
#  - Starts at 4-bit (best quality)
#  - Escalates to 3-bit → 2-bit as context grows
#  - Evicts oldest tokens when cache exceeds max_cache_len
#  - Never exceeds your memory budget

How Adaptive Mode Works

Context Length:   0 ──── 1K ──── 2K ──── 4K ──── 8K ──── 16K+
Bit Depth:       4-bit       3-bit       2-bit       eviction
Quality:         ████████  ██████░░  ████░░░░   ████░░░░
Memory:          ██░░░░░░  ████░░░░  ██████░░   ██████░░

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Compression Modes

Mode	Bits	Cosine Similarity	Compression	Best For
fast	4-bit	0.995	~2x	Production chatbots, high accuracy
balanced	3-bit	0.983	~3x	General purpose (recommended)
max_memory_save	2-bit	0.940	~4–6x	RAG pipelines, edge deployment
adaptive	dynamic	varies	~2–6x	Production serving, unknown workloads

Auto Mode (Policy Engine)

Let QuantCore pick the best mode for your GPU:

model = optimize_model(model, max_memory=0)  # Auto-detect GPU memory

GPU Memory	Auto-selected Mode
< 8 GB	max_memory_save (2-bit)
8–16 GB	balanced (3-bit)
16+ GB	fast (4-bit)

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Installation

pip install quantcore-ai

With all extras (torch, HF, dashboard):

pip install quantcore-ai[all]

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Supported Models

QuantCore automatically detects model architecture and extracts KV cache parameters:

• Llama (1B, 3B, 8B, 70B) — including Llama 3.x
• Mistral / Mixtral
• Phi-3 / Phi-4
• Gemma / Gemma 2
• Qwen / Qwen 2.5
• Falcon / StableLM / GPT-NeoX

Any HuggingFace PreTrainedModel with a standard config is supported. GQA and MHA architectures are handled automatically.

# Check any model's compatibility
quantcore info --model meta-llama/Llama-3.1-8B
quantcore info --model Qwen/Qwen2.5-7B
quantcore info --model google/gemma-2-9b

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CLI Tools

# Check model compatibility and see memory estimates
quantcore info --model meta-llama/Llama-3.1-8B

# Run synthetic benchmark (no GPU needed)
quantcore benchmark --mode all

# Start live monitoring dashboard
quantcore dashboard --port 8080

# Launch vLLM API server with compressed KV cache
quantcore serve --model meta-llama/Llama-3.1-8B --mode adaptive --max-memory 12GB

# Show version
quantcore version

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vLLM Integration (Production Serving)

from quantcore.vllm_integration import QuantCoreLLM

# Drop-in replacement for vllm.LLM with compressed KV cache
llm = QuantCoreLLM(
    "meta-llama/Llama-3.1-8B",
    mode="adaptive",
    max_memory="12GB",
    max_cache_len=8192,
)

outputs = llm.generate(["Explain KV cache compression in detail"])
print(outputs[0].outputs[0].text)

Or launch as an OpenAI-compatible API server:

quantcore serve --model meta-llama/Llama-3.1-8B --mode adaptive --max-memory 12GB

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Triton Fused Kernel (GPU Acceleration)

QuantCore includes a Triton fused attention kernel that computes Q·K^T directly from compressed uint8 indices — never materializing fp16 keys in GPU memory.

Standard:  Load fp16 keys → 2 bytes/elem → matmul
QuantCore: Load uint8 idx → 1 byte/elem → fused lookup+dot  (2x less HBM traffic)

The kernel auto-selects when a CUDA GPU with Triton is available. CPU inference falls back to PyTorch automatically.

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Monitoring Dashboard

quantcore dashboard --port 8080

Real-time browser dashboard showing:

• Memory savings (FP16 vs compressed)
• Compression ratio by mode
• KV cache growth over sequence length
• Interactive mode comparison

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How It Works

User Request
     |
LLM (HuggingFace / vLLM)
     |
QuantCore Layer (optimize_model)
     |
     +-- Random orthogonal rotation
     +-- Lloyd-Max scalar quantization (Beta-optimal codebook)
     +-- AdaptivePolicy (dynamic bit switching based on memory pressure)
     +-- Sliding window eviction (bounded memory)
     +-- Compressed KV Cache (2–4 bit per dimension)
     |
Efficient Inference (same output quality)

The algorithm applies a random orthogonal rotation to KV vectors, which induces a known Beta distribution on each coordinate. A Lloyd-Max codebook optimized for this distribution then quantizes each coordinate independently — no calibration data, no per-channel scales, works online.

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Benchmark Methodology

Read this before interpreting any benchmark numbers.

TurboQuant has two separate benchmark suites that measure different things.

Suite 1 — KV Compression Microbenchmarks (benchmarks/benchmark_suite.py)

These benchmarks evaluate KV compression fidelity and compressed attention microkernels using synthetic KV tensors — no model weights are loaded.

What they measure: VRAM reduction, compression ratio, cosine similarity, inner-product correlation (q·k vs q·k̂), RMSE, attention throughput, and quality drift across context lengths (4K / 8K / 32K).

What they do NOT measure: end-to-end LLM output quality, perplexity, full transformer decoding throughput, or production serving performance.

The tokens/sec figure is compressed KV inner-product throughput, not LLM generation speed. These differ by roughly 100×.

Suite 2 — End-to-End Evaluation (benchmarks/eval_e2e.py)

Real transformer forward passes with TurboQuant's cache patched in, measuring: perplexity delta (Δ PPL), needle-in-haystack retrieval, attention KL divergence, and greedy generation token agreement.

The default configuration uses a randomly-initialised GPT-2 architecture model (no download required). The compression code path is identical to what runs on pretrained models. To evaluate on pretrained weights, replace build_model("gpt2-small-sim") with AutoModelForCausalLM.from_pretrained(...).

Pass thresholds:

Bit depth	Max Δ PPL
4-bit	≤ 1.05
3-bit	≤ 1.15
2-bit	≤ 1.40

What is proven:

• ✅ Compression correctness and VRAM reduction (3–7×)
• ✅ Attention-space inner-product preservation (IP corr ≥ 0.99 at 4-bit)
• ✅ Context-length-independent quality
• ✅ Perplexity within threshold on architecture-equivalent model

What is not yet proven:

• ❌ Perplexity on pretrained models (WikiText-2, PG-19, LongBench)
• ❌ Real GPU throughput (requires CUDA hardware)
• ❌ Production serving metrics (vLLM batch throughput)

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Limitations (Honest)

• Short context (< 1K tokens): KV cache is small, savings are negligible. Model weights dominate memory.
• Output divergence: Compressed KV slightly shifts attention weights. At 4-bit this is nearly invisible; at 2-bit, generation may diverge from baseline after many tokens. Semantic meaning is preserved.
• Triton requirement: The fused GPU kernel requires a CUDA GPU + Triton. CPU inference uses PyTorch fallback (functional but slower).

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Feature Status

• HuggingFace plug-and-play integration
• Multi-architecture support (Llama, Mistral, Phi, Gemma, Qwen)
• Policy Engine (auto mode selection)
• CLI tools and monitoring dashboard
• Triton fused attention kernel (GPU-accelerated compression)
• vLLM integration (production serving)
• Adaptive runtime (dynamic bit switching + memory budgets)
• Sliding window eviction (bounded memory)
• PyPI release (pip install quantcore-ai)

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Paper

Based on: TurboQuant: Online Vector Quantization with Near-optimal Distortion Rate Zandieh, Daliri, Hadian, Mirrokni — Google Research, ICLR 2026 arxiv.org/abs/2504.19874

License

Apache 2.0