A Survey of VM

1
A Survey of VM04 and OSDI04

• Kenji Kaneda

2
??????????

• Towards Scalable Multiprocessor Virtual Machine
• Using Model Checking to Find Serious File System
  Errors
• Enhancing Server Availability and Security
  Through Failure-Oblivious Computing
• Recovering Device Drivers
• CP-Miner A Tool for Finding Copy-paste and
  Related Bugs in Operating System Code
• Configuration Debugging as Search Finding the
  Needle in the Haystack

3
Towards Scalable Multiprocessor Virtual Machines

• Volkmar Uhlig
• Joshua LeVasseur
• Espen Skoglund
• Uwe Dannowski
• (Universitat Karsruhe)

4
Background Multiprocessor Virtual Machine

• ?????MP???????MP???????
• E.g.) VMWare ESX server, cellular disco

PU
PU
PU
PU
PU
PU
Memory
Memory
Memory
Virtual
Physical
PU
PU
PU
PU
Memory
5
Background Multiprocessor Virtual Machine

• Multiplexing multiple virtual PUs
  on one physical PUs

PU
PU
PU
PU
PU
PU
Memory
Memory
Memory
Virtual
Physical
PU
PU
PU
PU
Memory
6
Problems with Scheduling of VMs (1/2)

• spin-lock??PU??????????
• ? Lock-holder?????????Lock?????????
• ???lock?????????PU???????

Lock???
Lock????
PU
PU
PU
PU
PU
PU
Virtual
???
Physical
PU
PU
PU
PU
7
Problems with Scheduling of VMs (2/2)

• ?PU????asymmetric???
• ? Guest OS?scheduling????????

??PU?100???
??PU? 50???
PU
PU
PU
PU
PU
PU
Virtual
Physical
PU
PU
PU
PU
8
Research Goal

• Scalable multiprocessor VM
• Avoids lock-holder preemption
• Schedules jobs with knowledge of asymmetric CPU
  speed

9
Lock-holder Preemption Avoidance

• Intrusive approach
• Guest OS?????
• Non-intrusive approach
• Guest OS??????

10
Intrusive Approach
?????OS????
???????OS????
lock??? critical section??? lock???
???????VM??? lock??? critical
section??? lock??? ???????VM???
11
Non-intrusive Approach

• ??????????????????????preemption?????
• user-level????
• HLT?????
• protocol handler?invoke?????

12
Scheduling with Knowledge of Asymmetric CPU Speed

• Time ballooning
• ??PU??????????????workload???

??PU?100???
Virtual machine
??PU? 50???
PU1
PU2
??workload
PU1?runqueue
PU2?runqueue
13
Experiments

• L4Ka???micro-kernel?????
• Apache2 benchmark??spin-lock? ?????
• ?10?????

14
Summary

• Scalable multiprocessor VM
• Avoids lock-holder preemption
• ? Intrusive and non-intrusive approach
• Schedules jobs with knowledge of asymmetric CPU
  speed
• ? Time ballooning

15
Using Model Checking to Find Serious File System
Errors

• Junfeng Yang
• Paul Twohey
• Dawson Engler
• Madanlal Musuvathi
• (Stanford University)
• (Microsoft Research)

16
File System Checker (Fisc)

• ?????????????????
• C Model Checker (CMC)??????????????
• Abstract specification????????????????????

17
Model Check???

• ??
• ?????????????
• ????
• ?????????????????????
• ?????????????????????
• ??????invariant
• fsck?recover?????
• ?????????????????????????

18
Experiments

• ext3, JFS, ReiserFS????????
• ?600??10K?????? (ext3)
• ? ?????????????????????

19
Enhancing Server Availability and Security
Through Failure-Oblivious Computing

• Martin Rinard
• Cristian Cadar
• Daniel Dumitran
• Daniel M. Roy
• Tudor Leu
• William S. Beebee, Jr.
• (MIT, Cambrige)

20
Background

• Memory errors are a common source of program
  failures
• E.g.) Buffer overflow
• ??????????????
• E.g.) safe-C compilers

21
Problems

• ???safe-C compiler?????? memory
  error?????????stuck??

22
Fail-Oblivious Computing (1/2)

• memory error??????????? ??????????
• ? An instance of Acceptability-oriented computing
  M. Rinard OOPSLA03
• Replaces the concept of program correctness with
  a set of acceptability properties

23
Fail-Oblivious Computing (2/2)

• Benefits
• Availability
• Security
• Minimal adoption cost
• Reduced administration overhead
• Drawbacks
• Unanticipated execution paths
• Bystander effect

24
Implementation (1/3)

• ???????????????????
• ????????????
• R. Jones and P. Kelly. Backwards-compatible
  bounds checking for arrays and pointers in C
  programs. In intl. workshop On Automatic
  Debugging, 1997.
• O. Ruwase and M. S. Lam. A Practical Dynamic
  Buffer Overflow Detector. In Annual Network and
  Distributed System Security Symposium, 2004.

25
Implementation (2/3)

• ?????????? ? ????
• ?????????? ??????????
• ?????????
• ??loop??????????

26
Implementation (3/3)

• ??????????????
• pointer in-equality comparison

27
Experiments

• Applications
• Apache, Sendmail, Pine, Midnight commander
• Results
• ????8????????
• ????????????????????????

28
Summary

• Fail-Oblivious Computing
• Enhances availability, resilience, and security
  by continuing to execute through memory errors

29
CP-Miner A Tool for Finding Copy-paste and
Related Bugs in Operating System Code

• Zhenmin Li
• Shan Lu
• Suvda Myagmer
• Yuanyuan Zhou
• (University of Illinois)

30
Background

• Copy-paste??????????????????
• E.g.) ?????????

31
Copy-paste?????????
for (iter 0
iterltnum_regs iter) prom_phys_totaliter.s
tart_adr prom_reg_memlistiter.phys_addr
prom_phys_totaliter.num_bytes
prom_reg_memlistiter.reg_size
prom_phys_totaliter.theres_more
prom_phys_totaliter1

for (iter 0
iterltnum_regs iter) prom_prom_takeniter.s
tart_adr prom_reg_memlistiter.phys_addr
prom_prom_takeniter.num_bytes
prom_reg_memlistiter.reg_size
prom_prom_takeniter.theres_more
prom_phys_totaliter1

prom_prom_taken????
32
CP-Miner

• data-mining????????? copy-paste??????????

33
Overview of Algorithm (1/4)

• ???????parse???statement??????????
• statement?token???
• E.g.) ??????????token?????
• E.g.) ???????????token?????
• token?????????????

for (iter 0 iterltnum_regs iter)
prom_phys_totaliter.start_adr
prom_reg_memlistiter.phys_addr
prom_phys_totaliter.num_bytes
prom_reg_memlistiter.reg_size
prom_phys_totaliter.theres_more
prom_phys_totaliter1
67651256
133862016
133862016
82589171
34
Overview of Algorithm (2/4)

• ??????????????sequence???????
• ????????????sequence?????sequence?????????

35
Overview of Algorithm (3/4)

• ??subsequence??
  ?????sequence?????????2?????????????
• CloSpan??????????????????????

36
Overview of Algorithm (4/4)

• ????????
• E.g.) ??????????????????

37
Experiments

• copy-paste?????????20??????
• Linux 190,000?
• FreeBSD 150,000?
• copy-paste????????
• Linux 28?
• FreeBSD 23?

38
Recovering Device Drivers

• Michael M. Swift
• Muthukaruppan Annamalai
• Brian N. Bershad
• Henry M. Levy
• (University of Washington)

39
Background

• Device Driver????????????????????
• E.g.) 85 of Windows XP crashes

40
Recovering Device Drivers

• ?????????????????????OS?????
• ???????????

41
System Overview
OS Kernel

• Shadow Driver? ?????

Kernel Interface
Sound Driver Class Interface
Sound Card Device Driver
Sound Card
42
System Overview

• ??????????????????????
• Nooks?????????
• ???????????????????????

43
??????
OS Kernel

• ????????
• E.g.) ioctl???????

Kernel Interface
Sound Driver Class Interface
Sound Card Device Driver
Sound Card
44
??????
OS Kernel

• ???????????????
• ????????????????????

Kernel Interface
Sound Driver Class Interface
Sound Card Device Driver
Sound Card
45
Configuration Debugging as Search Finding the
Needle in the Haystack

• Andrew Whitaker
• Richard S. Cox
• Steven D. Gribble
• (University of Washington)

46
Background

• Configuration errors
• E.g.) ?????????????????
• ??????????????????????????????????

47
Chronus

• ????probe??????????????????????????

48
System Overview

• Time-travel disk
• ????????????
• ?????????????????????????
• µDenali virtual machine

49
???????

• Binary search
• Time-travel disk????????????????????
• ??????????VM?boot???
  probe?????

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