Difference between revisions of "Operating Systems 2019W Lecture 22"
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Latest revision as of 21:11, 3 April 2019
Video
The video for the lecture given on April 3, 2019 is now available: Part 1, Part 2.
Notes
Lecture 22 ---------- Atomic operations Networking hardware virtualization Atomic operations ----------------- atom means "indivisible" in the original greek? an atomic operation is thus indivisible - it completes or it doesn't happen a transaction is a simulation of an atomic operation - if parts of the transaction fail, you undo everything Hardware virtualization ----------------------- want to run multiple operating systems on one system - so multiple kernels But kernels are special. They expect access to: - hardware-level interrupts - run in supervisor mode - devices - page tables - software interrupts (system call invocations) Two strategies: - fake it (emulation) - to make it fast, just emulate the privileged operations - original strategy of vmware on x86 - hardware virtualizes resources - hypervisor mode over supervisor mode (ring -1) - shadow page tables (virtualization of page tables) - devices are faked or do their own virtualization