Source: IEEE Pervasive Computing, Vol. 8, Issue.4, Oct.2009, pp. 14 – 23
Author: Satyanarayanan, M. , Bahl, P. , Caceres, R. , Davies, N.
Adviser: Chia-Nian Shyi
Speaker: 趙家寬
Date: 2010/11/2
1
Introduction
•
•
Mobile computing have developed the core
concepts, techniques and mechanisms.
Seamlessly augments the cognitive abilities
of users.
Speech recognition
Natural language processing
Computer vision and graphics
Machine learning
Augmented reality
Planning and decision-making
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Introduction
•
•
Virtual Machine (VM) technology to
rapidly customized service software on a
nearby cloudlet, then uses that service
over a wireless LAN.
Cloudlet also simplifies meeting
bandwidth demand of multiple users,
such as HD video and high-resolution
images.
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Resource-Poor Mobile Hardware
Mobile hardware is necessarily
resource-poor relative to static client and
server hardware.
 Improving size, weight and battery life
are higher priorities than enhancing
compute power.
 Resource poverty is a major obstacle for
many applications with the potential to
seamlessly augment human cognition.

4
The Limits of Cloud Computing
Cloud computing - solution to the
resource poverty of mobile devices.
 Long WAN latencies are a fundamental
obstacle.
 WAN delays in the critical path of user
interaction can hurt usability.

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The Limits of Cloud Computing

Lagar-Cavilla et al shows latency can
negatively impact interactive response in
spite of adequate bandwidth.
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How Cloudlets Can Help
Resource poverty of a mobile device
can be addressed by using a nearby
resource-rich cloudlet.
 The end-to-end response time of
applications executing in the cloudlet
needs to be fast (few milliseconds) and
predictable.

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How Cloudlets Can Help

Cloudlets are decentralized and widelydispersed Internet infrastructure.
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How Cloudlets Can Help

A cloudlet only contains soft state such
as cache copies of data or code that is
available elsewhere.
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Transient Cloudlet Customization
A key challenge is to simplify cloudlet
management.
 Solution is transient customization of
cloudlet infrastructure using hardware
virtual machine (VM) technology.
 Pre-use customization and Post-use
cleanup.

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Transient Cloudlet Customization
Two different approaches to delivering
VM state to infrastructure.
 VM migration approach

 Already-executing VM is first suspended,
processor, disk and memory state are then
transferred, VM execution is resumed at
the destination.
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Transient Cloudlet Customization

The other approach is called dynamic
VM synthesis.
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Transient Cloudlet Customization

Dynamic VM synthesis differs cloud in
two key ways. First its performance is
determined solely by local resources:
Bandwidth to cloudlet
Compute power of the cloudlet

Second, WAN failures do not affect
synthesis.
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Dynamic VM Synthesis
A proof-of-concept prototype called
Kimberley.
 The controller of the transient binding
between mobile device and cloudlet called
Kimberley Control Manager (KCM).

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Dynamic VM Synthesis

The first step in the binding sequence is
the establishment of a secure TCP
tunnel using SSL between KCM on a
device and a cloudlet.

After successful authentication, the
cloudlet KCM executes a command that
fetches the VM overlay from the mobile
device.
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Dynamic VM Synthesis

Decrypts and decompresses it, and
applies the overlay to the base VM.

The VM is then launched, and is ready
to provide services to the mobile device.
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Dynamic VM Synthesis
For use in cloudlets, rapid VM synthesis
is important.
 Cloudlet handoffs should be as rapid,
invisible and seamless.

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Dynamic VM Synthesis
Significant improvement is needed for
real-world deployment.
 The major contributors to VM synthesis
time are (a) overlay transmission and (b)
decompressing and applying the overlay
on the cloudlet.

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Dynamic VM Synthesis

To reduce decompression and overlay
application times, can exploit parallelism.

Partitioning the VM image into four parts
will allow a four-core cloudlet to
synthesize the parts.
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Conclusion
Resource poverty is a fundamental
constraint.
 A vision of mobile computing that breaks
free of this fundamental constraint.


Mobile users seamlessly utilize nearby
computers to obtain the resource
benefits of cloud computing without
incurring WAN delays and jitter.
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