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研究生: 吳邁龍
Wu, Mai-Lung
論文名稱: 已知與未知工作量排程最佳化工作流程時間的ℓ2範數
Optimizing the ℓ2-Norm of Job Flow Time with Clairvoyant and Non-Clairvoyant Schedules
指導教授: 郭桐惟
口試委員: 孫士勝
王超
學位類別: 碩士
Master
系所名稱: 資訊學院 - 資訊科學系
Department of Computer Science
論文出版年: 2026
畢業學年度: 114
語文別: 英文
論文頁數: 48
中文關鍵詞: 線上排程L2-範數流程時間自適應框架非全知排程ℓ2-範數
外文關鍵詞: Online Scheduling, L2-Norm, Flow Time, Adaptive Framework, Non-clairvoyant Scheduling, ℓ2-Norm
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  • 在線上排程中,沒有任何單一策略能在所有工作負載下表現良好。SRPT 能最小化平均流程時間,但當短工作持續到達時,大工作可能遭受飢餓;FCFS 依到達順序處理工作以防止飢餓,卻在大工作阻塞眾多小工作時造成浪費。流程時間的 ℓ₂-範數介於兩者之間:其平方懲罰對長延遲的抑制比平均值更為積極,但又不像最大值那樣僅關注單一最差工作。針對此目標,目前最佳的全知結果為 BAL,其競爭比為 O(n¹ᐟ³)——然而 BAL 需要事先得知工作總數,且其保障隨 n 增長而衰退。在非全知設定中,工作大小在完成前未知,現有演算法主要針對 ℓ₁-範數進行設計與分析,ℓ₂-範數作為策略選擇準則尚未被探索。本論文提出一個自適應框架,週期性地以近期工作負載歷史重播兩個競爭候選策略,並選擇 ℓ₂-範數較低者。三種實例展示此構想:Dynamic_BAL(BAL 對 FCFS,全知)、Dynamic(SRPT 對 FCFS,全知,無需工作總數)、以及 RFDynamic(RMLF 對 FCFS,非全知,採用池化模擬處理未知工作大小)。在 Bounded Pareto 與 Truncated Normal 工作負載、系統負載 0.75 至 1.50 的範圍內,每個實例在多數配置下均能匹配或優於其任一候選策略單獨使用的表現。


    1. Introduction 1
    1.1 Background and Motivation 1
    1.2 Two Problem Settings 2
    1.3 Research Contributions 3
    1.4 Thesis Organization 4
    2. Background 5
    2.1 Motivating Examples 5
    2.2 Clairvoyant Scheduling Algorithms 8
    2.2.1 SRPT 8
    2.2.2 FCFS 8
    2.2.3 BAL 9
    2.3 Non-Clairvoyant Scheduling Algorithms 9
    2.3.1 MLFQ and RMLF 10
    2.4 Summary: The Need for Adaptation 11
    3. Adaptive Framework Design 12
    3.1 Overview 12
    3.2 Core Mechanisms 13
    3.2.1 Batch-Based Execution 13
    3.2.2 Lookback and Policy Selection 13
    3.3 Clairvoyant Evaluation: Direct Replay 14
    3.4 Non-Clairvoyant Evaluation: Pool-Based Simulation 15
    3.4.1 The Challenge 15
    3.4.2 Bootstrap Phase 15
    3.4.3 Job Size Pool and Incomplete-Job Filling 15
    3.4.4 Simulation-Based Evaluation and Unified Pseudocode 16
    4. Experimental Evaluation 18
    4.1 Experimental Setup 18
    4.1.1 Job Arrival Process 18
    4.1.2 Job Size Distributions 18
    4.1.3 Baselines and Metrics 18
    4.2 Clairvoyant Results: Dynamic_BAL and Dynamic 19
    4.3 Non-Clairvoyant Results: RFDynamic 24
    4.4 Lookback Sensitivity Analysis 28
    4.5 Batch Size Sensitivity Analysis 30
    4.6 Time-Varying Workload 32
    4.7 Summary 34
    4.8 Discussion 34
    5. Related Work 36
    5.1 Minimizing Flow Time: Clairvoyant Setting 36
    5.2 Minimizing Flow Time: Non-Clairvoyant Setting 37
    5.3 Learning-Augmented Scheduling 39
    5.4 Summary 40
    6. Conclusion 41
    6.1 Summary of Contributions 41
    6.2 Future Work 42
    Reference 43

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