Exam 2 Review Brian Kocoloski CSE 522 S

Exam 2 Review Brian Kocoloski CSE 522 S - Advanced Operating Systems Washington University in St. Louis, MO 63130 1

Exam 2 • 6 Questions on comprehension – True/false, multiple choice, matching, open answer – No programming questions this time around • Recommended preparation: – Read the virtualization papers • Focus on the major architectural design – E. g. , KVM/Xen: » Type 1 or type 2 hypervisor? » Emulation or paravirtualization? » Shadow/nested paging? – Review the virtualization slides – Read the assigned LKD/LSP chapters – Review the studios CSE 522 S – Advanced Operating Systems 2

Core Concepts Virtualization was the main focus of the second half of the semester – focus most of your attention on the slides/papers on these topics CSE 522 S – Advanced Operating Systems 3

Core Concepts CPU Virtualization –Differences between hardware I/O Virtualization virtualization and emulation –Emulation vs Paravirtualization –New privilege separation mode vs Direct Assignment –Trap+emulate –Which modes require guest kernel changes? –What additional hardware Memory Virtualization support is needed for direct –Shadow paging vs nested assignment? paging – how they work –Shadow paging vs nested paging – which applications prefer which? –Address translation (how guest virtual->guest physical -> host physical works) CSE 522 S – Advanced Operating Systems 4

Core Concepts Process Forensics –/proc virtual filesystem –Types of things you can do with GDB (and how they work at the architectural level – e. g. , use of hardware registers) Memory Forensics –Dynamic memory allocation mistakes –MALLOC_CHECK, mallopt(), mallinfo() – cgroups memory limits Timing Forensics –Benchmarks vs. microbenchmarks (what are the differences and why both are important) –Kernel mechanisms to reduce non-determinism Internal anomalies –Local fork cascades –Using top and htop –Using /proc/ to find parentchild relationships, etc. CSE 522 S – Advanced Operating Systems 5

Next Wednesday (11/20) • Project Update Presentations • An opportunity for the instructor+other groups to provide early feedback – … and advice in case something is not working out as you had hoped! • Target 10 min + 2 or 3 min Q&A • Presentation does not need to be very polished, but should provide enough information to show that you’ve started making progress • Should include: 1. 2. 3. Motivation (why did you choose it / why is it interesting? ) Current status Challenges encountered + challenged expected CSE 522 S – Advanced Operating Systems 6