臺灣博碩士論文加值系統

本論文主要針對嵌入式系統的緩衝區管理策略上，提出減少執行期間 Context Switching 的方式以提高系統效能，並對 Task 執行期間 Deadline 的監控方面提出一個位於 Kernel Space 的方式，藉由 Task Miss Deadline 與否動態管理緩衝區以提高系統效能，此外由於 Context Switching 的減少並可同時減少系統的耗電量。
在耗電量管理方面，提出 Application Level DPM 的方法，配合 MontaVista Power Policy以管理不同應用程式的執行頻率，藉由降低執行頻率以減少系統耗電量。

A procedure is submitted to reduce Context Switching to improve system performance for buffer management strategy of the embedded system. And a Task Deadline Monitor Mechanism in Kernel Space is carried to dynamically manage buffer strategy by checking Task Miss Deadline to increase the system efficiency. Besides, it can reduce the power consumptions due to the decreasing of Context Switching.
For the management of power consumption, a way of Application Level DPM and MontaVista Power Policy to reduce the executing frequency for different application to save power consumption while system running.

一 緒論 1
1.1. 研究背景 1
1.2. 研究動機與目的 1
1.3. 章節概要 2
二 相關研究探討 3
2.1. 電源管理 3
2.1.1. 與系統耗電量的關係 4
2.1.2. 系統中主要耗電裝置與省電方式 6
2.1.3. 系統執行與工作電壓 7
2.1.4. DPM Policy 7
2.1.5. DPM Implement Layer 13
2.1.6. MontaVista 電源管理方式 14
2.2 DMA緩衝區 16
2.2.1 Audio DMA緩衝區行為模式 16
2.2.2 Semaphores 及 DMA 緩衝區 17
2.2.3 緩衝區大小與 Task Deadline 21
2.3 效能評估工具與方式 23
2.3.1 Context Switching Cost Benchmark 23
2.3.2 Context Switching 數量測量 24
2.3.3 Buffer Copy Latency Cost 25
三 系統設計 26
3.1 SYSTEM WIDE STATE MACHINE AND DEVICE STATE MACHINE 28
3.1.1. 使用UML設計 System Wide State Machine 28
3.1.2. System Wide State Machine 與系統頻率設定 34
3.1.3. Device State Machine及System Wide State Machine的相關性 35
3.2 SHUTDOWN MECHANISM 36
3.2.1. Device Shutdown 36
3.2.2. System Sleep 36
3.3 UP_TRIGGER METHOD 38
3.3.1 up_trigger Method DMA 緩衝區的使用情況 40
3.3.2 Task Deadline 監控與“Dynamic up_trigger Method” 43
四 實作與測試結果 46
4.1 UP_TRIGGER METHOD 系統效能測試 46
4.1.1 Context Switching 數量測試比較 47
4.2 CS 與系統耗電量測試 50
4.3 DPM POWER POLICY 管理耗電量測試 52
4.4 TASK DEADLINE 監控與動態 TRIGGER LEVEL系統效能測試 55
4.4.1 Context Switching 數量測試比較 55
4.4.2 Miss Task Deadline 測試比較 57
五 結論與未來展望 59
5.1 結論 59
5.1.1 CS 次數減少 59
5.1.2 Write Procedure Cost 減少 59
5.1.3 檔案讀寫效能增加 60
5.1.4 Context Switching 減少對系統功耗的幫助 60
5.1.5 System Wide State Machine (DPM) 與系統功耗關係 61
5.2 未來展望 61
參考資料 62

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