Virtualizing a Multiprocessor Machine on a Network of Computers

1. Virtualizing a Multiprocessor Machine on a Network of Computers Easy & efficient utilization of distributed resources Goal Kenji Kaneda Yoshihiro Oyama Akinori Yonezawa University of Tokyo JST Our Approach • Hide HW/SW complexityusingvirtualization techniques

2. Virtualization SMP with N processors N single-processor machines Virtual Multiprocessor Guest OS Virtual machine … Processor Processor Processor Shared memory I/O devices VMM VMM VMM Host OS Host OS Host OS Physical machine Physical machine Physical machine … Processor Processor Processor Memory Memory Memory I/O devices I/O devices I/O devices • ISA-level virtualization • Designed for Intel Pentium architecture • Paravirtualization

3. Virtualizing a Multiprocessor Machine on a Network of Computers Kenji Kaneda Yoshihiro Oyama Akinori Yonezawa University of Tokyo JST Implementation • Virtualizing processors Scheme to carry out instruction I on a virtual machine Physical machine’s processor carries out I directly I is sensitive? No Yes VMM interprets I (by trapping a general protection fault) • Instructions are sensitive if they interfere with the state of an underlying VMM or host OS

4. Virtualizing a memory • Paging mechanism • VMM maps pages to a memory according to a VM’s page directory/table • Kernel address space of a guest OS is shifted to avoid overlap with a host OS • Page fault exceptions • VMM intercepts exceptions that a physical machine generates • Memory consistency • VMM provides the illusion of a shared memory on top of distributed memories • Virtualizing I/O devices • VMM intercepts all I/O operations issued by a guest OS 0x00000000 0xa0000000 0xc0000000 0xffffffff User space Kernel space (Guest OS) Kernel space (Host OS) Linear address space Write X … Processor Processor Processor Virtual machine Shared memory Write X Processor Processor Processor … Physical machines Memory Memory Memory