INFS 803-Week 6 Cloud Resource Virtualization

第六周是讲虚拟化，其实虚拟化的架构什么的听着懵懵懂懂，但是这节课终于老师给了一道练习题，是关于计算的。因此，考试内容中可能会涉及到大量的计算，我很怀疑前面的计算也需要拿进来。所以回头得把前面的课题过一遍。

 Virtualization: motivation and concept
 Layering and virtualization.
 Dual mode execution and Processes
 Virtual memory and page replacement
 Virtual machine monitor.
 Virtual machine.
 x86 support for virtualization.
 Full and paravirtualization.
 Xen.

首先，简单介绍了抽象概念用来描述计算机系统，包括处理器，内存，和沟通的link

然后随着计算量，或者用户量的不断增加，慢慢的这种架构就面临着越来越大的挑战，例如如何处理峰值需求，heterogeneity 异质性。然后扯到了云计算的基础就是虚拟化。

Virtualization simulates the interface to a physical object by:虚拟化的几种方式
 Multiplexing: creates multiple virtual objects from one instance of a physical object. Many virtual objects to one physical. Example - a processor is multiplexed among a number of processes or threads.

多路复用
 Aggregation: creates one virtual object from multiple physical objects. One virtual object to many physical objects. Example - a number of physical disks are aggregated into a RAID disk.

聚合
 Emulation: constructs a virtual object of a certain type from a different type of a physical object. Example - a physical disk emulates a Random Access Memory (RAM).

仿真
 Multiplexing and emulation. Examples - virtual memory with paging multiplexes real memory and disk; a virtual address emulates a real address.

 Instruction Set Architecture (ISA) – at the boundary between hardware and software.
 Application Binary Interface (ABI) – allows the ensemble consisting of the application and the library modules to access the hardware; the ABI does not include privileged system instructions, instead it invokes system calls.
 ABI is the projection of the computer system seen by the process.
 Application Program Interface (API) - defines the set of instructions the hardware was designed to execute and gives the application access to the ISA; it includes high-level language (HLL) library calls which often invoke system calls

然后又开始听不懂了，全是底层架构