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APEX: An Extensible and Dynamism-Aware Simulator for Automated Parallel Execution in LLM Serving

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arxiv 2411.17651 v2 pith:IYLARS3Z submitted 2024-11-26 cs.DC

APEX: An Extensible and Dynamism-Aware Simulator for Automated Parallel Execution in LLM Serving

classification cs.DC
keywords apexplansservingexecutionbatchingefficientlyllmsoptimal
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Efficiently serving Large Language Models (LLMs) requires selecting an optimal parallel execution plan, balancing computation, memory, and communication overhead. However, determining the best strategy is challenging due to varying parallelism techniques (data, pipeline, tensor) and workload characteristics (e.g., compute-intensive tasks with long prompts vs. memory-intensive tasks with long generation). We propose APEX, an LLM serving system simulator that efficiently identifies optimal parallel execution plans by considering key factors of LLM serving systems, such as memory usage, batching behavior, etc. APEX performs dynamism-aware simulation to model iteration-level batching, and leverages LLMs' repetitive structure to reduce design space, scaling efficiently to trillion-scale models. APEX abstracts the key components of LLM serving systems, including the model, batching module, quantization formats, and device clusters, enabling the simulator to be general and extensible. Simulating on a CPU, APEX evaluates execution plans for various device clusters, covering diverse LLMs and workloads. APEX finds plans up to 3.37x faster than heuristics, and also plans that reduce energy consumption by up to 45% compared to latency-optimal plans. APEX performs comprehensive evaluations, reporting key system metrics like time per output token and time to first token, which can help service providers meet SLOs. APEX identifies an optimal plan within 15 minutes on a CPU, making it 71x faster and 1234x more cost-effective than cloud-based GPU deployment. APEX can be accessed at https://github.com/microsoft/apex_plus

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Forward citations

Cited by 8 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. AGENTSERVESIM: A Hardware-aware Simulator for Multi-Turn LLM Agent Serving

    cs.CL 2026-06 unverdicted novelty 7.0

    AGENTSERVESIM is a new simulator that models multi-turn LLM agent serving at program granularity and reproduces real-system performance within 6% error on commodity CPUs.

  2. Frontier: Towards Comprehensive and Accurate LLM Inference Simulation

    cs.DC 2026-05 unverdicted novelty 7.0

    Frontier is a new discrete-event simulator for disaggregated LLM serving that incorporates co-location, PDD, AFD, and optimizations, achieving under 4% throughput error and large reductions in latency prediction error...

  3. Dooly: Configuration-Agnostic, Redundancy-Aware Profiling for LLM Inference Simulation

    cs.DC 2026-05 unverdicted novelty 7.0

    Dooly reduces LLM inference profiling costs by 56.4% via configuration-agnostic taint-based labeling and selective database reuse, delivering simulation accuracy within 5% MAPE for TTFT and 8% for TPOT across 12 models.

  4. LLM-Emu: Native Runtime Emulation of LLM Inference via Profile-Driven Sampling

    cs.DC 2026-05 accept novelty 7.0

    LLM-Emu is a serving-native emulator for vLLM that replaces GPU execution with profile-driven latency sampling and achieves under 5% error on TPOT, ITL, E2E latency, and throughput across multiple models, GPUs, and workloads.

  5. KernelSight-LM: A Kernel-Level LLM Inference Simulator

    cs.PF 2026-06 unverdicted novelty 6.0

    KernelSight-LM simulates LLM inference at kernel granularity with cross-generation (12.1% per-kernel error) and target-measured (3.8% error) tiers, yielding end-to-end median errors of 15.4%/12.8%/3.0% and 14.3%/6.2%/...

  6. KernelSight-LM: A Kernel-Level LLM Inference Simulator

    cs.PF 2026-06 unverdicted novelty 6.0

    KernelSight-LM simulates token-level LLM inference to predict per-kernel latencies and end-to-end metrics (TTFT, TPOT, throughput) with 12.1% and 3.8% kernel errors in cross-generation and target-measured tiers.

  7. Dooly: Configuration-Agnostic, Redundancy-Aware Profiling for LLM Inference Simulation

    cs.DC 2026-05 unverdicted novelty 6.0

    Dooly reduces LLM inference profiling GPU-hours by 56.4% across 12 models while keeping simulation MAPE under 5% for TTFT and 8% for TPOT by making profiling configuration-agnostic and redundancy-aware.

  8. Rethinking Network Topologies for Cost-Effective Mixture-of-Experts LLM Serving

    cs.NI 2026-04 unverdicted novelty 6.0

    Switchless topologies such as 3D full-mesh are 20.6-56.2% more cost-effective than scale-up networks for MoE LLM serving, with current link bandwidths over-provisioned by up to 27%.