columbia universitycdall/pubs/cells_sosp2011-clean.pdfa virtual smartphone architecture 23rd acm...

A virtual Smartphone Architecture

23rd ACM Symposium on Operating Systems Principles, Cascais, Portugal, October 2011

Jeremy Andrus Christoffer Dall Alexander Van’t Hof Oren Laadan Jason Nieh

Columbia Universityin the city of new york

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Slides © 2011 Jeremy C. Andrus <[email protected]>

Personal PhoneBusiness Phone

Developer Phone

Children’s Phone

EvaluationOverview Graphics Cell Radio DemoMotivation Architecture

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VirtualizationEvaluationOverview Graphics Cell Radio DemoMotivation Architecture

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mailto:[email protected]





OSKernel

OSKernel

OSKernel

Bare-Metal Hypervisor

Hypervisor / VMM


Hardware

Server Virtualization

poor device support / sharing

4




OSOS

Host OS Kernel

OS

Hypervisor / VMM


Hosted HypervisorDesktop Virtualization

kernelmodule

Hardware

host user space

poor device performance

emulateddevices

5


OS Kernel


User Space SDKNon-Virtualization

no standard appsless secure custom user

space API for isolated apps

Hardware6




• device diversity

• mobile usage model➡ graphics-accelerated UI

Key Challenges

Power Buttons

WiFi

GPS

Cell Radio FramebufferGPU

Binder IPC

Touchscreen

Accelerometer

Compasspmem

microphone headset

speakers

microphone

camera(s)

h.264 accel.

RTC / Alarms


7




Cells

microphoneEvaluationOverview Graphics Cell Radio DemoMotivation Architecture

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Cells


Key Observation

large: lots of windows/apps

small:one app at a time

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Cells


Key Observation

screen real-estate is limited, and mobile phone users are accustomed to interacting with one thing at time

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Cells


Usage Model

foreground / background

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Cells


• multiple, isolated virtual phones (VPs) on a single mobile device

• 100% device support in each VP‣ unique phone numbers - single SIM!‣ accelerated 3D graphics!

Complete Virtualization

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Cells


• less than 2% overhead in runtime tests• imperceptible switch time among VPs

Efficient Virtualization

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Cells


• each VP sees / uses all devices• user can run any unmodified apps• foreground VP switches like an app

Transparent Virtualization

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LinuxKernel

•••

VP 3VP 2VP 1


Single Kernel: Multiple VPs

virtualize at OS interface

isolated collectionof processes

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LinuxKernel

•••


Single Kernel: Device Support

all VPs access the same device simultaneouslyPower

Cell Radio

Binder IPC

Accelerometer

Compasspmem

speakerscamera(s)

hw codec

RTC / Alarms

VP 3VP 2VP 1

Buttons

WiFi

GPS

FramebufferGPU

Touchscreen

microphone headset

•••

Sens

ors

Inpu

t

And

roid

...

Aud

io/V

ideo

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LinuxKernel

Pow

er

WiF

i

Cell

Radi

o

Fram

ebuf

fer

GPU

RTC

/ A

larm

s

•••

Sens

ors

Inpu

t

And

roid

...

Aud

io/V

ideo

•••


Device Namespaces

safely, correctly multiplex access

to devices

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device namespaces

VP 3VP 2VP 1




•••

LinuxKernel

Pow

er

WiF

i

Cell

Radi

o

Fram

ebuf

fer

GPU

RTC

/ A

larm

s

•••

Sens

ors

Inpu

t

And

roid

...

Aud

io/V

ideo


Cells

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VP 3VP 2VP 1

+device namespaces

foreground / background

device namespacesComplete, Efficient, TransparentMobile Virtualization

=




LinuxKernel

Pow

er

WiF

i

Cell

Radi

o

Fram

ebuf

fer

GPU

RTC

/ A

larm

s

•••

Sens

ors

Inpu

t

And

roid

...

Aud

io/V

ideo

GPU

Fram

ebuf

fer

19

device namespaces


Cell

Radi

o

efficient basic graphics virtualization

hardware accelerated graphics

proprietary/closed interface




virtual addressesphysical addresses


screen memory

Approach 1: Single Assignment

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GPU

Framebuffer


Framebuffer virtual state


screen memory

Approach 2: Emulated Hardware

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emulated framebuffer




virtual addressesphysical addresses

mux_fb

screen memory


VP 3

backgroundmux_fb presentsidentical deviceinterface to all VPsusing device namespaces

swap virt addr mappings:point to different phys addr

Cells: Device Namespaces

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VP 1

Framebuffer

VP 2

backgroundforeground


screen memory


Accelerated Graphics

MMU

context

VP 2

OpenGL

VP 1

context

OpenGL OpenGL

context

VP 3

graphics virtual addressesphysical addresses

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Framebuffer

GPU

VP: just a setof processes!

process isolation


GPUMMU graphics virtual addresses

physical addresses

screen memory


Device Namespace + Graphics Context

context

VP 2

OpenGL

VP 1

context

OpenGL OpenGL

context

VP 3

background

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foreground background


LinuxKernel


Drivers

Baseband: GSM / CDMA

RilD

VoIP?

VoIP VoIPVendor RIL

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LinuxKernel


GSM/CDMA

RilD

Dual-SIM?

Vendor RIL

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GSM / CDMA

Drivers Drivers

RilD

Vendor RIL





Root Namespace

LinuxKernel

vendor API


Drivers

Baseband: GSM / CDMA

Cells RIL

RilD

VP 2

Cells RIL

RilD

VP 1

RilD

Cells RIL

VP 3Cells: User-Level Namespace Proxy

backgroundbackgroundforeground

Vendor RIL

proprietary hardware/software requires a well-defined interface.

27

CellD



Experimental ResultsSetup

• Nexus S• five virtual phones

• overhead vs. stock 〈Android 2.3〉

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Experimental ResultsSetup

• CPU 〈Linpack〉

• graphics 〈Neocore〉

• storage 〈Quadrant〉

• web browsing 〈Sun Spider〉

• networking 〈Custom WiFi Test〉

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Runtime Overhead

0.00!

0.20!

0.40!

0.60!

0.80!

1.00!

1.20!

1.40!

Linpack NeoCore Quadrant I/O

Sun Spider

Network

1-VP! 2-VP! 3-VP! 4-VP! 5-VP!Negligible

Overhead In 3D Measurements!


Experimental Results

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Demo


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• device namespaces‣ safely and efficiently share devices

• foreground / background‣ designed specifically for mobile devices

• implemented on Android• less than 2% overhead on Nexus S

CellsComplete, Efficient, Transparent

Mobile Virtualization

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More Info

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cellrox.comcells.cs.columbia.edu



http://cellrox.com

http://cellrox.com

http://cells.cs.columbia.edu

http://cells.cs.columbia.edu

columbia universitycdall/pubs/cells_sosp2011-clean.pdfa virtual smartphone architecture 23rd acm...

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