【摘要】：在虛擬化環(huán)境下，通過改變底層的存儲硬件可以大幅提升虛擬機讀寫性能及效率。固態(tài)硬盤（SSD）與傳統(tǒng)的機械硬盤相比，具有低延時，低能耗，高吞吐率，高帶寬等眾多優(yōu)勢。但需要注意的是，在虛擬化環(huán)境下引入SSD并不是簡單的物理替換，由于其自身的結(jié)構(gòu)和特點，使得SSD的重要設(shè)備指令trim不能通過虛擬機傳遞至底層的SSD，從而引起了SSD使用性能的嚴重下降。因此，如何打破虛擬機與底層硬件的語義鴻溝，在引入SSD后準確的將trim指令傳遞至底層硬件，成為亟待解決的問題。 虛擬化環(huán)境下引入SSD的優(yōu)化系統(tǒng)Vtrim（trim for Virtual Block Devices）可以實時將trim指令傳遞至底層的SSD。trim指令需要經(jīng)由操作系統(tǒng)的刪除操作進行觸發(fā)，但在虛擬機中的刪除操作由于虛擬化語義鴻溝的存在無法觸發(fā)trim指令。針對這種情況，，Vtrim系統(tǒng)將虛擬機中的刪除操作進行實時的監(jiān)控。當虛擬機文件要被刪除時，Vtrim系統(tǒng)截獲這種行為并實時的將刪除語義傳至虛擬機管理域（domain0），而后將虛擬機中的刪除行為在domain0中進行相應(yīng)的語義解析。解析語義完畢后，將會獲得對應(yīng)虛擬機磁盤鏡像文件上所需要刪除的位置及刪除長度，利用domain0的刪除操作可以觸發(fā)trim指令的特點，在domain0中將虛擬機磁盤鏡像上需要刪除的部分使用文件打洞的方式進行刪除，從而觸發(fā)trim指令，實現(xiàn)了SSD在虛擬化環(huán)境下的性能的優(yōu)化。 功能測試證明，Vtrim可以在虛擬機運行的情況下，實時的截獲、傳遞、解析、并在本地執(zhí)行刪除操作，有效的將trim指令傳遞至底層SSD的主控中。性能分析證明，針對使用半虛擬化的虛擬機而言，使用Vtrim進行長期優(yōu)化的虛擬機，相比長期未優(yōu)化的虛擬機來說，虛擬機磁盤隨機寫性能最大可提高將近150%，平均響應(yīng)時延最大可減少至原來的40%左右。
[Abstract]:In virtualized environment, the performance and efficiency of virtual machine reading and writing can be greatly improved by changing the underlying storage hardware. Compared with traditional mechanical hard disk, (SSD) has many advantages, such as low delay, low energy consumption, high throughput and high bandwidth. However, it is important to note that the introduction of SSD in a virtualized environment is not a simple physical replacement, because of its own structure and characteristics, The important device instruction trim of SSD can not be passed through virtual machine to the underlying SSDs, which results in a serious deterioration of SSD performance. Therefore, how to break the semantic gap between the virtual machine and the underlying hardware and accurately transfer the trim instructions to the underlying hardware after the introduction of SSD has become an urgent problem to be solved. Vtrim (trim for Virtual Block Devices), an optimization system that introduces SSD into virtualization environment, can transfer trim instructions to the underlying SSD.trim instructions in real time, which need to be triggered by the delete operation of the operating system. However, the delete operation in virtual machine can not trigger the trim instruction because of the semantic gap of virtualization. In this case, the Vtrim system monitors the delete operation in the virtual machine in real time. When the virtual machine file is to be deleted, the Vtrim system intercepts this behavior and transmits the deletion semantics to the virtual machine management domain (domain0) in real time. Then the delete behavior in the virtual machine is parsed in the domain0. After parsing the semantics, the location and length of deletion needed to be deleted on the corresponding virtual machine disk image file will be obtained. The deletion operation of domain0 can trigger the characteristics of the trim instruction. In domain0, some parts of virtual machine disk image that need to be deleted are deleted by the way of file hole, which triggers the trim instruction, and realizes the optimization of the performance of SSD in the virtualization environment. The function test shows that Vtrim can intercept, transfer, parse and delete the trim instructions in real time when the virtual machine is running, and effectively transfer the trim instructions to the master control of the underlying SSD. Performance analysis shows that for virtual machines with paravirtualization, virtual machines with Vtrim for long-term optimization, compared with long-unoptimized virtual machines, The maximum random write performance of virtual machine disk can be improved by nearly 150 and the average response delay can be reduced to about 40%.
【學位授予單位】：華中科技大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TP333.35

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