高位元處理機下單一位址空間作業系統的虛擬位址轉換及保護

Abstract

傳統的虛擬記憶體管理多被用於像Unixㄧ樣的私有虛擬空間的作業系統. 但並不能有效地用於單一位址空間作業系統(Single Address Space Operating System). 在這篇論文中, 我們提出一個新的虛擬記憶體保護 模組來管理單一位址空間. 藉著將64位元的虛擬位址空間分成二的三十二 次方個位元的區段, 作業系統須管理關於每個行程的區段表以及每個區段 的位址轉換表. 每個區段表上記錄這個行程可存取的區段以及區段的位址 轉換表的位置. 藉著將區段表暫存在我們所提出的一個新快取記憶體架構 上, 位址之轉換及存取權限之檢查的時間都會縮短. 而且藉由分開的位址 轉換及位址保護快取架構, 傳統耗費在行程轉換所作的虛工也大量被減 少. 在我們的模擬結果中顯示, 這個虛擬記憶體管理架構的確增加了在單 一位址空間作業系統中虛擬記憶體轉換及保護的效能. 提要(英) Conventional virtual memory schemes are used to supportprivate address space operating systems, such as UNIX. They cannot handlevirtual memory management of single address space operating systems onmodern 64-bit architectures. In this thesis, we introduce a new memoryprotection model to manage single virtual address space, called thesegment based protection model (SGB). It partitions 64-bit virtual addressspace into 2^32 segments with 2^32 bytes each. With this protection model,the operating system maintains a separate segment table for each process,and each segment table records the segments this process can access andthe addresses of the translation page tables of these segments are located.Then, by caching the per-process basis segment table on a new memory cache, called the segment lookaside buffer (SLB), the virtual addresstranslation time and protection rights verification time are reduced.Furthermore, by separating the hardware mechanism for translation andprotection, data stored in translation lookaside buffer (TLB) can be sharedby all processes, and need not be flushed on context switch. The cost ofcontext switch on conventional architectures is greatly reduced. The simulation results show that our memory architecture greatlyimproves the performance of virtual address translation and protection forsingle address space operating systems on wide address architectures.