Core Insights - The article discusses the challenges of achieving reproducibility in large language model (LLM) inference, highlighting that even with the same input, different outputs can occur due to the probabilistic nature of the sampling process [10][11] - It introduces the concept of "batch invariance" in LLM inference, emphasizing the need for consistent results regardless of batch size or concurrent requests [35][40] Group 1 - Thinking Machines Lab, founded by former OpenAI CTO Mira Murati, has launched a blog series called "Connectionism" to share insights on AI research [3][8] - The blog's first article addresses the non-determinism in LLM inference, explaining that even with a temperature setting of 0, results can still vary [10][12] - The article identifies floating-point non-associativity and concurrency as key factors contributing to the uncertainty in LLM outputs [13][24] Group 2 - The article explains that the assumption of "concurrency + floating-point" as the sole reason for non-determinism is incomplete, as many operations in LLMs can be deterministic [14][16] - It discusses the importance of understanding the implementation of kernel functions in GPUs, which can lead to unpredictable results due to the lack of synchronization among processing cores [25][29] - The article emphasizes that most LLM operations do not require atomic addition, which is often a source of non-determinism, thus allowing for consistent outputs during forward propagation [32][33] Group 3 - The concept of batch invariance is explored, indicating that the results of LLM inference can be affected by the batch size and the order of operations, leading to inconsistencies [36][40] - The article outlines strategies to achieve batch invariance in key operations like RMSNorm, matrix multiplication, and attention mechanisms, ensuring that outputs remain consistent regardless of batch size [42][60][64] - It concludes with a demonstration of deterministic inference using batch-invariant kernel functions, showing that consistent outputs can be achieved with the right implementation [74][78]

Core Viewpoint - The article discusses the challenges of achieving reproducibility in large language models (LLMs) due to the lack of batch invariance, which leads to nondeterministic outputs even under controlled conditions [10][41][46]. Group 1: Introduction to the Issue - Thinking Machines Lab, founded by former OpenAI CTO Mira Murati, published its first article addressing nondeterminism in LLM inference [1][3]. - The blog aims to cover a wide range of topics related to their research, including numerical computation and prompt engineering [3]. Group 2: Understanding Nondeterminism - Reproducibility is a cornerstone of scientific progress, yet obtaining consistent results from LLMs is challenging [10]. - Even with the temperature parameter set to 0, LLM APIs can still produce nondeterministic outputs [11]. - The nondeterminism is attributed to floating-point non-associativity and concurrency, which affects the order of operations in GPU computations [13][30]. Group 3: The Root Cause of Nondeterminism - The article argues that the common assumption linking concurrency and floating-point operations to nondeterminism does not fully explain the issue [14][30]. - Floating-point non-associativity leads to different results based on the order of operations, especially in parallel computations [19][26]. - The actual implementation of kernel functions in LLMs contributes to the nondeterministic behavior observed [27][30]. Group 4: Batch Invariance - The lack of batch invariance is identified as a key factor causing nondeterminism in LLM outputs [41][46]. - Batch size changes can lead to different results for the same input, which is counterintuitive for mathematical functions [43]. - The article emphasizes that ensuring kernel functions are batch invariant is crucial for achieving consistent outputs in LLM inference [46]. Group 5: Solutions for Achieving Determinism - The article outlines strategies to implement batch invariance in key operations such as RMSNorm, matrix multiplication, and attention mechanisms [49][60][71]. - By ensuring that the operations do not depend on batch size, the LLM inference can produce consistent results [46][81]. - The authors provide a demonstration of deterministic inference using their batch-invariant kernel function library [82]. Group 6: Performance Considerations - Initial performance tests indicate that while the batch-invariant kernel functions may not be fully optimized, they do not lead to catastrophic performance declines [89]. - The article highlights the importance of maintaining performance while achieving deterministic outputs in LLMs [88]. Group 7: Implications for Reinforcement Learning - The article discusses how achieving deterministic inference can facilitate true on-policy reinforcement learning by ensuring consistent outputs between training and inference [90]. - This consistency is essential for effective training and sampling processes in reinforcement learning environments [90]. Group 8: Conclusion - The article advocates for a proactive approach to understanding and addressing the sources of nondeterminism in LLMs, encouraging the community to strive for reproducibility in AI systems [93].