CS 533 Concepts of Operating Systems Class 16

CS 533 Concepts of Operating Systems Class 16 Exokernel & Specialization CS 533 - Concepts of Operating Systems 1

Questions q What is the difference between virtualization and secure multiplexing? o o q What do Exokernel and Disco have in common? What do Exokernel and Xen have in common? Do Xen or Disco do secure multiplexing? Does Exokernel create virtual machines? Is Exokernel a micro-kernel? o What abstractions does it support? CS 533 - Concepts of Operating Systems 2

Questions q q What is a "process" in the Exokernel? Does the Exokernel "paravirtualize" privileged instructions? How are address translations and physical memory managed in the Exokernel? How does Exokernel’s visible revocation relate to scheduler activations? o q How does it differ from Xen and Disco in this respect? How does PCT relate to LRPC? o What is the difference between synchronous and asynchronous PCT? CS 533 - Concepts of Operating Systems 3

Questions q q q How does Exokernel use hardware support to improve performance? How are "software caches" used to improve performance? How is "downloaded code" used to improve performance? o o o q How does this relate to Sandboxing? How does this relate to SPIN? How does this relate to Specialization? What do hardware support, software caches and downloaded code have in common? CS 533 - Concepts of Operating Systems 4

Questions q What does specialization have to do with extensibility? o o o Why do people want extensible kernels? Is the interface or the implementation the problem? What does specialization do? CS 533 - Concepts of Operating Systems 5

Questions q q What impact do conventional forms of extensibility have on software engineering concerns? What impact does specialization have on software engineering concerns? o o What if its tool-assisted? What if its fully automated? CS 533 - Concepts of Operating Systems 6

Reminder q For information on hand-coded specialization see: "Optimistic Incremental Specialization: Streamlining a Commercial Operating System", Calton Pu, Tito Autrey, Andrew Black, Charles Consel, Crispin Cowan, Jon Inouye, Lakshmi Kethana, Jonathan Walpole, and Ke Zhang, In Proceedings of the 15 th ACM Symposium on Operating Systems Principles (SOSP'95), December 3 -6, 1995, Copper Mountain, Colorado. http: //www. cs. pdx. edu/~walpole/papers/sosp 1995. pdf q Send me a draft of your slides early CS 533 - Concepts of Operating Systems 7