TACCL: Guiding Collective Algorithm Synthesis using Communication Sketches
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Abstract (arXiv)
Machine learning models are increasingly being trained across multiple GPUs and servers. In this setting, data is transferred between GPUs using communication collectives such as AlltoAll and AllReduce, which can become a significant bottleneck in training large models. Thus, it is important to use efficient algorithms for collective communication. We develop TACCL, a tool that enables algorithm designers to guide a synthesizer into automatically generating algorithms for a given hardware configuration and communication collective. TACCL uses a novel communication sketch abstraction to get crucial information from the designer to significantly reduce the search space and guide the synthesizer towards better algorithms. TACCL also uses a novel encoding of the problem that allows it to scale beyond single-node topologies. We use TACCL to synthesize algorithms for three collectives and two hardware topologies: DGX-2 and NDv2. We demonstrate that the algorithms synthesized by TACCL outperform the Nvidia Collective Communication Library (NCCL) by up to 6.7x. We also show that TACCL can speed up end-to-end training of Transformer-XL and BERT models by 11%--2.3x for different batch sizes.
Key facts. Cited by 38 papers in the map (data through 7 Oct 2026). Builds on 15 of its 51 references that are in the map. First posted on arXiv 8 Nov 2021.
Builds on
15 of 51 references.
References · 15
- 2018BERT: Pre-training of Deep Bidirectional Transformers for Language Understandingcited by 40,204
- 2021Switch Transformers: Scaling to Trillion Parameter Models with Simple and Efficient Sparsitycited by 3,014
- 2019Transformer-XL: Attentive Language Models Beyond a Fixed-Length Contextcited by 1,830
- 2019Megatron-LM: Training Multi-Billion Parameter Language Models Using Model Parallelismcited by 1,829
- 2020GShard: Scaling Giant Models with Conditional Computation and Automatic Shardingcited by 1,601
- 2018Horovod: fast and easy distributed deep learning in TensorFlowcited by 275
- 2021Software-Hardware Co-design for Fast and Scalable Training of Deep Learning Recommendation Modelscited by 78
- 2017Learning to Infer Graphics Programs from Hand-Drawn Imagescited by 73
- 2019Scaling Distributed Machine Learning with In-Network Aggregationcited by 62
- 2019Blink: Fast and Generic Collectives for Distributed MLcited by 34
- 2020Synthesizing Optimal Collective Algorithmscited by 30
- 2020Is Network the Bottleneck of Distributed Training?cited by 19
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Citing papers per year: 2022: 1; 2023: 4; 2024: 9; 2025: 12; 2026: 12.
38 papers.
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- 2024FLUX: Fast Software-based Communication Overlap On GPUs Through Kernel Fusioncited by 53
- 2025MegaScale-Infer: Serving Mixture-of-Experts at Scale with Disaggregated Expert Parallelismcited by 31
- 2023CASSINI: Network-Aware Job Scheduling in Machine Learning Clusterscited by 26
- 2024T3: Transparent Tracking & Triggering for Fine-grained Overlap of Compute & Collectivescited by 15
- 2024Communication-Efficient Large-Scale Distributed Deep Learning: A Comprehensive Surveycited by 9
- 2025MSCCL++: Rethinking GPU Communication Abstractions for AI Inferencecited by 9
- 2024Swing: Short-cutting Rings for Higher Bandwidth Allreducecited by 8
- 2024Domino: Eliminating Communication in LLM Training via Generic Tensor Slicing and Overlappingcited by 8
- 2022Efficient Direct-Connect Topologies for Collective Communicationscited by 5
- 2025Characterizing the Efficiency of Distributed Training: A Power, Performance, and Thermal Perspectivecited by 5
- 2023TACOS: Topology-Aware Collective Algorithm Synthesizer for Distributed Machine Learningcited by 4
- 2024Enhancing Large-Scale AI Training Efficiency: The C4 Solution for Real-Time Anomaly Detection and Communication Optimizationcited by 4
26 more
- 2025Collective Communication for 100k+ GPUscited by 4
- 2025Reliable and Resilient Collective Communication Library for LLM Training and Servingcited by 4
- 2026UniEP: Unified Expert-Parallel MoE MegaKernel for LLM Trainingcited by 4
- 2024Communication Optimization for Distributed Training: Architecture, Advances, and Opportunitiescited by 3
- 2025Towards Easy and Realistic Network Infrastructure Testing for Large-scale Machine Learningcited by 3
- 2025Robust Heuristic Algorithm Design with LLMscited by 3
- 2024ForestColl: Throughput-Optimal Collective Communications on Heterogeneous Network Fabricscited by 2
- 2023Bandwidth Optimal Pipeline Schedule for Collective Communicationcited by 1
- 2023Network Contention-Aware Cluster Scheduling with Reinforcement Learningcited by 1
- 2025Efficient AllReduce with Stragglerscited by 1
- 2026Stage-Aware Communication Scheduling for Disaggregated LLM Servingcited by 1
- 2026GF-DiT: Scheduling Parallelism for Diffusion Transformer Servingcited by 1
- 2024MLCC: A Congestion Control Technique to Accelerate ML Trainingcited by 0
- 2025GPU-centric Communication Schemes for HPC and ML Applicationscited by 0
- 2025LUMION: Fast Fault Recovery for ML Jobs Using Programmable Optical Fabricscited by 0
- 2025Morphlux: Transforming Torus Fabrics for Efficient Multi-tenant MLcited by 0
- 2025Enabling Reconfiguration-Communication Overlap for Collective Communication in Optical Networkscited by 0
- 2026FreeScale: Distributed Training for Sequence Recommendation Models with Minimal Scaling Costcited by 0
- 2026HetCCL: Enabling Collective Communication For Mixed-Vendor Heterogeneous Clusterscited by 0
- 2026Don't Let a Few Network Failures Slow the Entire AllReducecited by 0
- 2026AoiZora: Topology-Aware Auto-Parallel Optimization for Inference of Diffusion Transformerscited by 0
- 2026Distributed Training using an Intelligent Networkcited by 0
- 2026Tuning Collective Patterns to Alleviate Congestion in Shared AI Clusterscited by 0
- 2026HDA-MoE: Hybrid Parallelism and Dynamic, Adaptive Scheduling for Mixture-of-Experts with 3D Near-Memory Processingcited by 0
- 2026mKernel: Fast Multi-GPU, Multi-Node Fused Kernelscited by 0
- 2026Purlin: Separating Orchestration from the Datapath of Collectivescited by 0
- 2026Purlin: Separating Orchestration from the Datapath of Collectives29 Sep 2026
- 2026mKernel: Fast Multi-GPU, Multi-Node Fused Kernels11 Sep 2026
- 2026HDA-MoE: Hybrid Parallelism and Dynamic, Adaptive Scheduling for Mixture-of-Experts with 3D Near-Memory Processing8 Sep 2026
- 2026Tuning Collective Patterns to Alleviate Congestion in Shared AI Clusters3 Sep 2026
- 2026Distributed Training using an Intelligent Network26 Aug 2026
- 2026AoiZora: Topology-Aware Auto-Parallel Optimization for Inference of Diffusion Transformers16 Jun 2026
- 2026GF-DiT: Scheduling Parallelism for Diffusion Transformer Serving11 Jun 2026
- 2026Don't Let a Few Network Failures Slow the Entire AllReduce1 Jun 2026
- 2026HetCCL: Enabling Collective Communication For Mixed-Vendor Heterogeneous Clusters29 May 2026
- 2026FreeScale: Distributed Training for Sequence Recommendation Models with Minimal Scaling Cost27 Apr 2026
- 2026UniEP: Unified Expert-Parallel MoE MegaKernel for LLM Training21 Apr 2026
- 2026Stage-Aware Communication Scheduling for Disaggregated LLM Serving18 Mar 2026
26 more
- 2025Reliable and Resilient Collective Communication Library for LLM Training and Serving31 Dec 2025
- 2025Collective Communication for 100k+ GPUs23 Oct 2025
- 2025Enabling Reconfiguration-Communication Overlap for Collective Communication in Optical Networks22 Oct 2025
- 2025Robust Heuristic Algorithm Design with LLMs9 Oct 2025
- 2025Characterizing the Efficiency of Distributed Training: A Power, Performance, and Thermal Perspective12 Sep 2025
- 2025Morphlux: Transforming Torus Fabrics for Efficient Multi-tenant ML20 Jul 2025
- 2025Efficient AllReduce with Stragglers29 May 2025
- 2025LUMION: Fast Fault Recovery for ML Jobs Using Programmable Optical Fabrics29 May 2025
- 2025Towards Easy and Realistic Network Infrastructure Testing for Large-scale Machine Learning29 Apr 2025
- 2025MSCCL++: Rethinking GPU Communication Abstractions for AI Inference11 Apr 2025
- 2025MegaScale-Infer: Serving Mixture-of-Experts at Scale with Disaggregated Expert Parallelism3 Apr 2025
- 2025GPU-centric Communication Schemes for HPC and ML Applications31 Mar 2025
- 2024Domino: Eliminating Communication in LLM Training via Generic Tensor Slicing and Overlapping23 Sep 2024
- 2024FLUX: Fast Software-based Communication Overlap On GPUs Through Kernel Fusion11 Jun 2024
- 2024Enhancing Large-Scale AI Training Efficiency: The C4 Solution for Real-Time Anomaly Detection and Communication Optimization7 Jun 2024
- 2024Communication-Efficient Large-Scale Distributed Deep Learning: A Comprehensive Survey9 Apr 2024
- 2024Communication Optimization for Distributed Training: Architecture, Advances, and Opportunities12 Mar 2024
- 2024MLCC: A Congestion Control Technique to Accelerate ML Training14 Feb 2024
- 2024ForestColl: Throughput-Optimal Collective Communications on Heterogeneous Network Fabrics9 Feb 2024
- 2024T3: Transparent Tracking & Triggering for Fine-grained Overlap of Compute & Collectives30 Jan 2024
- 2024Swing: Short-cutting Rings for Higher Bandwidth Allreduce17 Jan 2024
- 2023Network Contention-Aware Cluster Scheduling with Reinforcement Learning31 Oct 2023
- 2023CASSINI: Network-Aware Job Scheduling in Machine Learning Clusters1 Aug 2023
- 2023Bandwidth Optimal Pipeline Schedule for Collective Communication29 May 2023
- 2023TACOS: Topology-Aware Collective Algorithm Synthesizer for Distributed Machine Learning11 Apr 2023
- 2022Efficient Direct-Connect Topologies for Collective Communications7 Feb 2022
- 2025MegaScale-Infer: Serving Mixture-of-Experts at Scale with Disaggregated Expert Parallelismcited by 31
- 2026UniEP: Unified Expert-Parallel MoE MegaKernel for LLM Trainingcited by 4
- 2026HDA-MoE: Hybrid Parallelism and Dynamic, Adaptive Scheduling for Mixture-of-Experts with 3D Near-Memory Processingcited by 0
- 2026HDA-MoE: Hybrid Parallelism and Dynamic, Adaptive Scheduling for Mixture-of-Experts with 3D Near-Memory Processing8 Sep 2026
- 2026UniEP: Unified Expert-Parallel MoE MegaKernel for LLM Training21 Apr 2026
- 2025MegaScale-Infer: Serving Mixture-of-Experts at Scale with Disaggregated Expert Parallelism3 Apr 2025
- 2024FLUX: Fast Software-based Communication Overlap On GPUs Through Kernel Fusioncited by 53
- 2023CASSINI: Network-Aware Job Scheduling in Machine Learning Clusterscited by 26
- 2024T3: Transparent Tracking & Triggering for Fine-grained Overlap of Compute & Collectivescited by 15
- 2024Communication-Efficient Large-Scale Distributed Deep Learning: A Comprehensive Surveycited by 9
- 2025MSCCL++: Rethinking GPU Communication Abstractions for AI Inferencecited by 9
- 2024Swing: Short-cutting Rings for Higher Bandwidth Allreducecited by 8
- 2024Domino: Eliminating Communication in LLM Training via Generic Tensor Slicing and Overlappingcited by 8
- 2022Efficient Direct-Connect Topologies for Collective Communicationscited by 5
- 2025Characterizing the Efficiency of Distributed Training: A Power, Performance, and Thermal Perspectivecited by 5
- 2023TACOS: Topology-Aware Collective Algorithm Synthesizer for Distributed Machine Learningcited by 4
- 2024Enhancing Large-Scale AI Training Efficiency: The C4 Solution for Real-Time Anomaly Detection and Communication Optimizationcited by 4
- 2025Collective Communication for 100k+ GPUscited by 4
12 most cited of 32 All 32 (JSON)
- 2026Purlin: Separating Orchestration from the Datapath of Collectives29 Sep 2026
- 2026mKernel: Fast Multi-GPU, Multi-Node Fused Kernels11 Sep 2026
- 2026Tuning Collective Patterns to Alleviate Congestion in Shared AI Clusters3 Sep 2026
- 2026Distributed Training using an Intelligent Network26 Aug 2026
- 2026Don't Let a Few Network Failures Slow the Entire AllReduce1 Jun 2026
- 2026HetCCL: Enabling Collective Communication For Mixed-Vendor Heterogeneous Clusters29 May 2026
- 2026FreeScale: Distributed Training for Sequence Recommendation Models with Minimal Scaling Cost27 Apr 2026
- 2025Reliable and Resilient Collective Communication Library for LLM Training and Serving31 Dec 2025
- 2025Collective Communication for 100k+ GPUs23 Oct 2025
- 2025Enabling Reconfiguration-Communication Overlap for Collective Communication in Optical Networks22 Oct 2025
- 2025Robust Heuristic Algorithm Design with LLMs9 Oct 2025
- 2025Characterizing the Efficiency of Distributed Training: A Power, Performance, and Thermal Perspective12 Sep 2025
12 newest of 32 All 32 (JSON)