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Enterprise AI Analysis: Enhancing LLM Efficiency: Targeted Pruning for Prefill-Decode Disaggregation in Inference

Enterprise AI Analysis

Enhancing LLM Efficiency: Targeted Pruning for Prefill-Decode Disaggregation in Inference

Authors: Hao Zhang, Mengsi Lyu, Yulong Ao, Yonghua Lin

Affiliation: Beijing Academy of Artificial Intelligence

Executive Impact

Our innovative pruning method for Large Language Models delivers significant performance gains and cost reductions, making advanced AI more accessible and efficient for enterprise deployment.

0 Inference Speedup
0 Bandwidth Reduction
0 Avg. Performance Score (PD Disaggregation)

Deep Analysis & Enterprise Applications

Select a topic to dive deeper, then explore the specific findings from the research, rebuilt as interactive, enterprise-focused modules.

Overview
Methodology
Experiments
Conclusion

Strategic LLM Pruning for Enhanced Efficiency

Large Language Models (LLMs) demonstrate exceptional capabilities across various tasks, but their deployment is constrained by high computational and memory costs. Model pruning provides an effective means to alleviate these demands. However, existing methods often ignore the characteristics of prefill-decode (PD) disaggregation in practice. Our novel pruning method for PD disaggregation inference enables more precise and efficient block and KV Cache pruning, achieving a 20.56% inference speedup and a 4.95× reduction in data transmission bandwidth consumption.

20.56% Average Inference Speedup
4.95x Data Transmission Bandwidth Reduction

Stage-Aware Pruning & KV Cache Optimization

We propose a novel pruning method for PD disaggregation inference, enabling more precise and efficient block and KV Cache pruning. Our approach constructs pruning and distillation sets to perform iterative block removal independently for the prefill and decode stages, obtaining better pruning solutions. We introduce a token-aware cache pruning mechanism that retains all KV Cache in the prefill stage but selectively reuses entries for the first and last token sequences in selected layers during decode, reducing communication costs with minimal overhead.

Enterprise Process Flow: Prefill-Decode Disaggregation with Pruning

Prefill Node Processes Prompts
Distinct Block Removal (Pruning & Distillation) Applied
KV Cache Generated (Full on Prefill)
Selected KV Cache Transmitted to Decode
Decode Node Processes Tokens with Pruned Model & KV Cache
Key Differentiators of Our Method
Feature Our Method Traditional Pruning
Approach to Prefill-Decode
  • Stage-aware: Independent pruning for prefill and decode stages
  • Uniform pruning across stages, ignoring distinct sensitivities
Block Pruning Strategy
  • Iterative block removal with dedicated pruning and distillation sets for better solutions
  • Often greedy selection, unstable, limited to local optimal solutions
KV Cache Pruning
  • Token-aware, selective reuse for first/last tokens in selected layers, minimal overhead, reduced bandwidth
  • Often requires retraining, management overhead, overlooks attention heads' granularity
Efficiency Focus
  • Reduced bandwidth via targeted KV Cache pruning, precise block removal
  • Primarily model size reduction, less focus on communication costs in disaggregated systems

Robust Performance Across Models & Benchmarks

Extensive experiments demonstrate that our approach consistently achieves strong performance in both PD disaggregation and PD unified settings without disaggregation. Our method achieves a 20.56% inference speedup and a 4.95× reduction in data transmission bandwidth consumption, outperforming existing baselines across various LLMs and benchmarks including LLaMA3.1-8B, LLaMA2-13B, and Qwen2.5-7B.

Performance Comparison (LLaMA3.1-8B, Avg Score)
Method Avg Score
Dense65.46
LLM-Pruner56.07
FLAP56.11
Shortened53.66
ShortGPT56.08
SLEB48.42
Ours62.99
Data Transmission & Speed (LLaMA3.1-8B)
Method DataVol (G) Speed (µs)
Original4.011628
Ours0.82347
PD Disaggregation vs. Unified Performance (LLaMA2-13B)
Strategy Avg Score
Unified47.31
Disaggregation (Ours)49.50

Qualitative Generation Performance

Despite substantial reduction in model size, our pruned model consistently generates coherent, information-rich, and well-structured responses, retaining the core semantics of the original output. This confirms strong generation capabilities and factual consistency.

Prompt: Explain what artificial intelligence is.

Original Output: Artificial intelligence (AI) is the simulation of human intelligence processes by machines, especially computer systems. These processes include learning, reasoning, and self-correction. Particular applications of AI include...

Pruned Output: Artificial intelligence, or AI, is a field of computer science that deals with the creation of machines that can perform tasks that normally require human intelligence. This includes things such as understanding natural language, recognizing objects in images, and making decisions based on complex data.

Summary & Future Directions

We proposed a pruning method deeply integrated with PD disaggregation, constructing pruning and distillation sets for iterative block removal independently tailored to prefill and decode stages, achieving superior solutions. Our token-aware KV Cache pruning mechanism reduces bandwidth usage with negligible overhead. Experimental results confirm strong performance in both PD disaggregation and PD unified settings. Future work includes pruning-aware memory management strategies and MoE pruning within the PD disaggregation framework, further enhancing efficiency.

Calculate Your Potential ROI

See how targeted LLM efficiency can translate into significant operational savings and reclaimed hours for your enterprise.

Estimated Annual Savings $0
Total Hours Reclaimed Annually 0

Your AI Implementation Roadmap

Our structured approach ensures a smooth integration of advanced LLM efficiency techniques into your existing enterprise infrastructure.

Phase 1: Discovery & Assessment

Comprehensive analysis of your current LLM deployment, identifying key optimization opportunities and assessing existing infrastructure for Prefill-Decode Disaggregation suitability.

Phase 2: Strategy & Customization

Develop a tailored pruning and KV Cache optimization strategy, leveraging our stage-aware block removal and token-aware cache pruning methods, customized to your specific models and workloads.

Phase 3: Implementation & Integration

Execute the pruning and optimization plan, seamlessly integrating the efficient LLM into your enterprise systems. Includes model fine-tuning and validation on your specific datasets.

Phase 4: Monitoring & Ongoing Optimization

Continuous performance monitoring, iterative refinement of pruning parameters, and adaptive adjustments to ensure sustained efficiency and optimal performance in dynamic environments.

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Our experts are ready to help you implement targeted pruning for unprecedented performance and cost savings. Don't let computational overhead limit your AI's potential.

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