Research map / Large language models / Reasoning and chain of thought
Hogwild! Inference: Parallel LLM Generation via Concurrent Attention
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Proposes Hogwild! Inference, which runs multiple instances of the same LLM in parallel over a shared, concurrently updated KV cache using RoPE-based cache rotation, letting reasoning models collaborate zero-shot.
Problem
Existing parallel LLM inference schemes (voting, SoT-style fixed decomposition, asynchronous threads) impose a fixed collaboration framework that suits only some tasks and cannot re-plan; the paper asks whether LLM workers can coordinate on the fly without a predefined framework while avoiding costl
Approach
Run several workers of the same LLM in one batch that share a single KV cache: each worker sees other workers' tokens as they are generated by rotating KV blocks to worker-specific positions, implemented by rotating only the current query per block (RoPE property), with a chat-like step-structured cache layout and s1-style prompts; no fine-tuning is used.
Key results
- On LIMO with QwQ-32B, Hogwild! Inference reaches higher accuracy than the sequential baseline at equal sequential-step budgets, with larger gains as workers increase from 2 to 4.
- On QwQ-32B-AWQ on an NVIDIA L40S, Hogwild! generates tokens about 2x faster with 2 workers and about 3.2-3.6x faster with 4 workers.
- GPT-4o collaborativeness scores are much higher for token-wise synchronized Hogwild! than for independent generation (no sync) or step-wise sync.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| Use Hogwild! Inference instead of sequential generation | QwQ-32B-AWQ · LIMO | accuracy at a fixed time budget | Helped |
| Use Hogwild! Inference with 2 workers instead of sequential inference | QwQ-32B-AWQ · token generation | tokens per second: nearly twice as fast | Helped |
| Use Hogwild! Inference with 4 workers instead of sequential inference | QwQ-32B-AWQ · token generation | tokens per second: 3.2{-}3.6× faster | Helped |
| Use Hogwild! Inference instead of the single-worker baseline | QwQ-32B · LIMO | accuracy at a fixed number of consecutive steps | Helped |
| Use Hogwild! Inference instead of the single-worker baseline | QwQ-32B · GSM8K×5 | per-question accuracy | No clear effect |
| Use the combined cache layout rather than the contiguous layout (ablation) | Hogwild! Inference · LIMO | accuracy at longer reasoning budgets | Helped |
| Use token-wise synchronization rather than step-wise synchronization (ablation) | Hogwild! Inference · LIMO | accuracy at smaller budgets | Helped |
| Add the collaboration prompt asking whether the worker is doing redundant work (ablation) | Hogwild! Inference · LIMO | accuracy-budget trade-off | Helped |
| Use cache rotation instead of re-encoding worker tokens at new positions (ablation) | Hogwild! Inference · LIMO | accuracy | Mixed |
| Use multiple workers rather than a single worker (ablation) | Hogwild! Inference · LIMO, smaller budgets | accuracy | Helped |
| Synchronize workers token-wise rather than only after completed reasoning steps (ablation) | Hogwild! Inference · LIMO | GPT-4o collaborativeness score | Helped |
Surprising findings
- Off-the-shelf reasoning models (QwQ-32B, Qwen3, Phi-4-R+, DeepSeek-R1) collaborate via the shared cache without any fine-tuning.
- Qwen3-1.7B and to a lesser extent Qwen3-4B get distracted and fail to adapt to the shared-cache collaboration setup.
Limitations
- Reduced robustness on smaller models and longer contexts.
- Collaboration quality is judged by a proprietary model (GPT-4o), limiting reproducibility.
- Relies on prompting; models often but not always detect redundant work.
Experimental setup
Datasets: GSM8K LIMO LiveCodeBench OlympiadBench AIME'25
Benchmarks: GSM8K x5 (synthetic) LIMO LiveCodeBench v5 OlympiadBench AIME'25
Metrics: accuracy vs sequential token budget Pass@1 collaborativeness score (1-6) tokens per second latency
Baselines: Baseline (sequential with early stopping) Skeleton-of-Thought Self-consistency
Builds on: Self-Consistency Skeleton-of-Thought Hogwild! SGD Flash-Decoding PagedAttention s1
Closest papers by meaning
- RelayCaching: Accelerating LLM Collaboration via Decoding KV Cache Reuse (ICML 2026 · similarity 0.89)
- Bag of Tricks for Inference-time Computation of LLM Reasoning (NeurIPS 2025 · similarity 0.89)
- PARALLELPROMPT: Extracting Parallelism from Large Language Model Queries (NeurIPS 2025 · similarity 0.89)
- Skeleton-of-Thought: Prompting LLMs for Efficient Parallel Generation (ICLR 2024 · similarity 0.89)
- Cache-to-Cache: Direct Semantic Communication Between Large Language Models (ICLR 2026 · similarity 0.89)
- A Two-Tier Perspective on Inference-Time Parallelism in Multi-Agent LLM Systems (ICML 2026 · similarity 0.88)
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