USENIX Association Proceedings of the Third Virtual Machine Research and Technology Symposium San Jose, CA, USA May 6–7, 2004 © 2004 by The USENIX Association All Rights Reserved For more information about the USENIX Association: Phone: 1 510 528 8649 FAX: 1 510 548 5738 Email:
[email protected] WWW: http://www.usenix.org Rights to individual papers remain with the author or the author's employer. Permission is granted for noncommercial reproduction of the work for educational or research purposes. This copyright notice must be included in the reproduced paper. USENIX acknowledges all trademarks herein. Towards Scalable Multiprocessor Virtual Machines Volkmar Uhlig Joshua LeVasseur Espen Skoglund Uwe Dannowski System Architecture Group Universitat¨ Karlsruhe
[email protected] Abstract of guests, such that they only ever access a fraction of the physical processors, or alternatively time-multiplex A multiprocessor virtual machine benefits its guest guests across a set of physical processors to, e.g., ac- operating system in supporting scalable job throughput commodate for spikes in guest OS workloads. It can and request latency—useful properties in server consol- also map guest operating systems to virtual processors idation where servers require several of the system pro- (which can exceed the number of physical processors), cessors for steady state or to handle load bursts. and migrate between physical processors without no- Typical operating systems, optimized for multipro- tifying the guest operating systems. This allows for, cessor systems in their use of spin-locks for critical sec- e.g., migration to other machine configurations or hot- tions, can defeat flexible virtual machine scheduling due swapping of CPUs without adequate support from the to lock-holder preemption and misbalanced load.