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arXiv 2201.01811cs.LGcs.AIcs.NIstat.ML
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CausalSim:用于无偏迹线驱动模拟的因果框架

CausalSim: A Causal Framework for Unbiased Trace-Driven Simulation

MIT(麻省理工学院)

Abdullah Alomar, Pouya Hamadanian, Arash Nasr-Esfahany, Anish Agarwal, Mohammad Alizadeh, Devavrat Shah

AI总结:

CausalSim提出因果框架,通过张量补全消除迹线偏差,实现无偏模拟,在真实数据上误差降低53%和61%,并揭示ABR算法新见解。

摘要:

我们提出了CausalSim,一个用于无偏迹线驱动模拟的因果框架。当前的迹线驱动模拟器假设被模拟的干预(例如,新算法)不会影响迹线的有效性。然而,现实世界的迹线常常受到算法在迹线收集过程中所做选择的影响而产生偏差,因此在干预下重放迹线可能导致错误的结果。CausalSim通过学习系统动态的因果模型以及捕捉迹线收集期间潜在系统条件的潜在因素来解决这一挑战。它使用固定算法集下的初始随机对照试验(RCT)来学习这些模型,然后在模拟新算法时应用这些模型来消除迹线数据中的偏差。CausalSim的关键是将无偏迹线驱动模拟映射为一个具有极其稀疏观测的张量补全问题。通过利用RCT数据中存在的基本分布不变性,CausalSim实现了新颖的张量补全方法,尽管观测稀疏。我们在真实和合成数据集上对CausalSim进行了广泛评估,包括来自Puffer视频流系统的超过十个月的真实数据,结果表明它提高了模拟准确性,与专家设计和监督学习基线相比,平均误差减少了53%和61%。此外,与有偏基线模拟器相比,CausalSim提供了关于ABR算法的显著不同见解,我们通过实际部署进行了验证。

英文摘要:

We present CausalSim, a causal framework for unbiased trace-driven simulation. Current trace-driven simulators assume that the interventions being simulated (e.g., a new algorithm) would not affect the validity of the traces. However, real-world traces are often biased by the choices algorithms make during trace collection, and hence replaying traces under an intervention may lead to incorrect results. CausalSim addresses this challenge by learning a causal model of the system dynamics and latent factors capturing the underlying system conditions during trace collection. It learns these models using an initial randomized control trial (RCT) under a fixed set of algorithms, and then applies them to remove biases from trace data when simulating new algorithms. Key to CausalSim is mapping unbiased trace-driven simulation to a tensor completion problem with extremely sparse observations. By exploiting a basic distributional invariance property present in RCT data, CausalSim enables a novel tensor completion method despite the sparsity of observations. Our extensive evaluation of CausalSim on both real and synthetic datasets, including more than ten months of real data from the Puffer video streaming system shows it improves simulation accuracy, reducing errors by 53% and 61% on average compared to expert-designed and supervised learning baselines. Moreover, CausalSim provides markedly different insights about ABR algorithms compared to the biased baseline simulator, which we validate with a real deployment.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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