VIRTUAL MACHINE VERSATILE PLATFORM01~chapter 1 (1).ppt
- 1. Virtual Machines: Versatile Platforms for Systems and Processes J. E. Smith University of Wisconsin-Madison Ravi Nair IBM Thomas J. Watson Research Center
- 2. INTRODUCTION This material is based on the book, Virtual Machines: Versatile Platforms for Systems and Processes, Copyright 2005 by Elsevier Inc. All rights reserved. It has been used and/or modified with permission from Elsevier Inc.
- 3. Introduction 3 Course Objectives Study VM architectures and applications Study key implementation technologies Focus on architecture and microarchitecture aspects Cover significant case studies
- 4. Introduction 4 Introduction Why are virtual machines interesting? They allow transcending of interfaces (which often seem to be an obstacle to innovation) They enable innovation in flexible, adaptive software & hardware, security, network computing (and others) They involve computer architecture in a pure sense Virtualization will be a key part of future computer systems A fourth major discipline? (with HW, System SW, Application SW)
- 5. Introduction 5 Advantages of Standard Interfaces Major design tasks are decoupled • In space and time Different hardware and software development schedules Software can run on any machine supporting a compatible interface PowerPC MacOS MacIntosh apps. x86 Linux Linux apps x86 Windows Windows apps.
- 6. Introduction 6 There are also disadvantages… Software compiled for one ISA will not run on hardware with a different ISA • Apple Mac (PowerPC) binaries on an x86? Even if ISAs are the same, OSes may differ • Windows NT applications on a Solaris x86? Binary may not be optimized for the specific hardware platform it runs on • Intel Pentium 4 binaries on an AMD Athlon? MacOS MacIntosh apps x86 x86 Windows apps. Linux
- 7. Introduction 7 Disadvantages (contd.) Innovation may be inhibited by fixed ISA • Hard to add new instructions OR remove obsolete ones • What was the most recent (successful) new ISA? Or new OS? Difficult for software to interact directly with implementation • Performance features • Power management • Fault tolerance • Software is supposed to be implementation independent
- 8. Introduction 8 Hardware Resources Conventional system software manages hardware resources directly • An OS manages the physical memory of a specific size • I/O devices are managed as physical entities Difficult to share resources except through OS • All users of hardware must use the same OS • All users are vulnerable to attack from other users sharing the resource (via security holes in OS)
- 9. Introduction 9 Abstraction Computer systems are built on levels of abstraction Higher level of abstraction hide details at lower levels Example: files are an abstraction of a disk file file abstraction I/O devices and Networking Controllers System Interconnect (bus) Controllers Memory Translation Execution Hardware Drivers Memory Manager Scheduler Operating System Libraries Application Programs Main Memory Software Hardware
- 10. Introduction 10 Virtualization An isomorphism from guest to host • Map guest state to host state • Implement “equivalent” functions Si S Si ' Sj' Guest Host V(Si) V(Sj) e(Si) e'(Si') j
- 11. Introduction 11 Virtualization Similar to abstraction Except • Details not necessarily hidden Construct Virtual Disks • As files on a larger disk • Map state • Implement functions VMs: do the same thing with the whole “machine” file file virtualization
- 12. Introduction 12 Application Program Interface • API • User ISA + library calls The “Machine” Different perspectives on what the Machine is: OS developer Compiler developer Application programmer Instruction Set Architecture • ISA • Major division between hardware and software Application Binary Interface • ABI • User ISA + OS calls I/O devices and Networking System Interconnect (bus) Memory Translation Execution Hardware Application Programs Main Memory Operating System Libraries
- 13. Introduction 13 The “Machine” Different perspectives on what the Machine is: OS developer Instruction Set Architecture • ISA • Major division between hardware and software I/O devices and Networking System Interconnect (bus) Memory Translation Execution Hardware Application Programs Main Memory Operating System Libraries
- 14. Introduction 14 The “Machine” Different perspectives on what the Machine is: Compiler developer Application Binary Interface • ABI • User ISA + OS calls I/O devices and Networking System Interconnect (bus) Memory Translation Execution Hardware Application Programs Main Memory Operating System Libraries
- 15. Introduction 15 The “Machine” Different perspectives on what the Machine is: Application programmer Application Program Interface • API • User ISA + library calls I/O devices and Networking System Interconnect (bus) Memory Translation Execution Hardware Application Programs Main Memory Operating System Libraries
- 16. Introduction 16 Hardware "Machine" OS Applications Virtualizing Software Virtual Machine OS Applications Guest VMM Host Virtual Machines add Virtualizing Software to a Host platform and support Guest process or system on a Virtual Machine (VM) Example: System Virtual Machine
- 17. Introduction 17 The Family of Virtual Machines Lots of things are called “virtual machines” IBM VM/370 Java VMware Some things not called “virtual machines”, are virtual machines IA-32 EL Dynamo Transmeta Crusoe
- 18. Introduction 18 Taking a Unified View “The subjects of virtual machines and emulators have been treated as entirely separate. … they have much in common. Not only do the usual implementations have many shared characteristics, but this commonality extends to the theoretical concepts on which they are based” -- Efrem G. Wallach, 1973
- 19. Introduction 19 Major Program Interfaces ISA Interface -- supports all conventional software System Calls User ISA System ISA ISA Application Software Operating System System Calls User ISA System ISA ABI Application Software Operating System Application Binary Interface (ABI) -- supports application software only
- 20. Introduction 20 System Virtual Machines Provide a system environment Constructed at ISA level Persistent Examples: IBM VM/360, VMware, Transmeta Crusoe guest process HOST PLATFORM virtual network communication Guest OS VMM guest process guest process guest process Guest OS2 VMM guest process guest process
- 21. Introduction 21 System Virtual Machines Native VM System • VMM privileged mode • Guest OS user mode • Example: classic IBM VMs User-mode Hosted VM • VMM runs as user application Dual-mode Hosted VM • Parts of VMM privileged; parts non-privileged • Example VMware Non-privileged modes Privileged Mode Virtual Machine VMM Hardware Virtual Machine Host OS Hardware VMM Virtual Machine Host OS Hardware VMM
- 22. Introduction 22 Process VMs Execute application binaries with an ISA different from hardware platform Couple at ABI level via Runtime System Examples: IA-32 EL, FX!32 Virtualizing Software Application Process Machine OS Hardware Guest Runtime Host Application Process Virtual Machine
- 23. Introduction 23 Process Virtual Machines Constructed at ABI level Runtime manages guest process Not persistent Guest processes may intermingle with host processes As a practical matter, guest and host OSes are often the same Dynamic optimizers are a special case Examples: IA-32 EL, FX!32, Dynamo HOST OS Disk file sharing network communication guest process create host process guest process runtime runtime guest process runtime host process
- 24. Introduction 24 Same-ISA Dynamic Binary Optimizers Optimize Binary at Runtime An ABI level optimization A type of Process VM Example HP Dynamo • Can optimize for dynamic properties of program • Can optimize for a specific processor implementation HP PA UNIX HP Apps
- 25. Introduction 25 HLL VMs Java and CLI are recent examples Binary class files are distributed “ISA” is part of binary class format OS interaction via APIs (part of VM platform) Sparc Workstation Java Binary Classes x86 PC Apple Mac VM implementation VM implementation VM implementation Java VM Architecture
- 26. Introduction 26 High Level Language Virtual Machines Raise the level of abstraction • User higher level virtual ISA • OS abstracted as standard libraries Process VM (or API VM) HLL Program Intermediate Code Memory Image Object Code (ISA) Compiler front-end Compiler back-end Loader HLL Program Portable Code (Virtual ISA ) Host Instructions Virt. Mem. Image Compiler VM loader VM Interpreter/Translator Traditional HLL VM
- 27. Introduction 27 Co-Designed VMs VLIW Windows X86 Apps Perform both translation and optimization VM provides interface between standard ISA software and implementation ISA Primary goal is performance or power efficiency Use proprietary implementation ISA Transmeta Crusoe and IBM Daisy best-known examples
- 28. Introduction 28 Composition ISA 2 OS 1 apps 2 OS 1 apps 1
- 29. Introduction 29 Composition: Example Java application Linux x86 JVM Windows x86 VMware Crusoe VLIW Code Morphing
- 30. Introduction 30 Summary (Taxonomy) VM type (Process or System) Host/Guest ISA same or different Multiprogrammed Systems Java VM MS CLI Transmeta Crusoe same ISA different ISA Process VMs System VMs Virtual PC for Mac different ISA same ISA IBM VM/370 VMware HP Dynamo IA-32 EL FX!32
- 31. Introduction 31 Course Topics Introduction & VM Overview Emulation: Interpretation & Binary Translation Process VMs & Dynamic Translators Dynamic Binary Optimization Co-Designed VMs HLL VMs System VMs Emerging Applications
- 32. Introduction 32 Case Studies Shade Sun WABI Compaq FX!32 HP Dynamo VMware Transmeta Crusoe IBM Daisy Intel VT-x …. and others