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Samsung will present the challenges of creating a dual-Android platform on the Nexus 10 using Xen on ARM. Running two copies of Android is a strong use-case to satisfy the security needs for BYOD (Bring Your Own Device), where one Android can be designated as “work” and is secure and isolated from the users “home” Android. Achieving a good user-experience in both Android is essential for this technology to succeed commercially. The Nexus 10 has ARM Cortex A15 processors. For a good user-experience, both Android need high-performance GPU-accelerated graphics which demand high throughput and low latency. Samsung will discuss the issues encountered using Xen on a mobile device in this demanding use-case, and how the changes for Xen for mobile can be contributed into the community.
Citation preview
Dual-AndroidTM on Nexus 10
10/21/2013 © Samsung Electronics 1
Samsung Research UK Presentation
for
Xen Developer Summit
24-25 Oct 2013
Edinburgh, UK
2 © Samsung Electronics
Introduction
Feasibility: 2 copies of Android on Xen on ARM?
o Xen on mobile performance?
o Virtualized GPU required
Nexus 10 device used
o CPU: ARM Cortex A15 (x2)
o GPU: ARM Mali T604
o Memory available: 2GB RAM, plenty of Flash
o Screen resolution: 2560x1504
3 © Samsung Electronics
Configuration
Software configuration – 2 VMs only
o DOM0 = 1st Android
o DOMU = 2nd Android
o Linux 3.4
o Android Jelly Bean 4.2
Xen 4.2 for ARM
o Builds on Xen on ARM for Cortex A9 work in Samsung
o Parallel development in Samsung HQ to community
Xen DOM0 kernel DOMU kernel
Memory 1GB RAM 1GB RAM
SMP Dual-core Dual-core Single-core
I/O Pass through PV Drivers
Xen PVH Architecture
4 © Samsung Electronics
DOMU DOM0
Android
Jelly Bean 4.2
GPU
Mali T604
CPU 0
(Cortex A15)
Kernel
(PL1)
User
(PL0)
HYP
(PL2)
Android
Apps
Linux 3.4
HW CPU 1
(Cortex A15)
Android
Jelly Bean 4.2
Android
Apps
Linux 3.4
Xen on ARM
Rings Physical
Drivers
Back End
Drivers
Front End
Drivers
Display,
Touch
etc.
5 © Samsung Electronics
Mobile Virtualization
I/O Challenges – Mobiles have ~50 device drivers
o Sensors: Touch, gyro, proximity, ambient light
o Media: Display, GPU, Camera, Audio, Video
o Connectivity: Charger, USB, WiFi, Bluetooth
User Switching
o Xen scheduler runs as normal.
o “Foreground” VM – user devices require arbitration driver in DOM0
• Display
• Touch
Display
Switch
Foreground VM
6 © Samsung Electronics
Video
DOM0 – Blue Wallpaper DOMU – Orange Wallpaper
Switching icon
Demo video
o Switching between Android Icon or Volume key
o Angry Birds in DOMU Near-native performance of PV drivers
o Angry Birds in DOM0 and DOMU concurrently Two independent Android
o 3D Benchmark clip
Passthrough drivers PV Drivers
7 © Samsung Electronics
Near-Native Performance Challenges
60 frames per second = 16.6ms per frame
o GPU renders each surface GPU composes the surfaces frame
Virtualized graphics options
o API Remoting done above GPU driver for chipset portability
Android JB has “butter smooth” technology
o Triple buffering
o Needs reliable Vsync interrupt Xen event channel stressed
o Deferred waiting using sync points & fences
15 0 30 45 60 time (ms)
Composition frame buffers
0
1
2
0
1
2 App frame buffers
8 © Samsung Electronics
Results
0
20
40
60
80
100
120
140
160
0
10
20
30
40
50
60
70
Packets
/sec (
k)
FP
S
Dual-Android, GPU composition
DOM0 DOMU Packets/sec (k)
9 © Samsung Electronics
Event Channel Under Stress
DOMU Vsync arrival time delta
16.67
0
5
10
15
20
25
30
35
10 11 12 13 14 15 16 17 18 19 20
De
lta
Tim
e (
ms
)
Benchmark Time (sec)
Some
missed
events
10 © Samsung Electronics
Xen For Mobile
Multi-page ring
o Needed for throughput performance running benchmarks
o Ensure low-latency
Non-linear grant references
o Old grants are re-used. PV drivers assume linearity
RAM Allocation limit 512MB
o Buddy allocator is unable to allocate contiguous chunk of memory from the Domheap
memory
Per-VM interrupts unreliable when stressed
o Must ensure Vsync is received in DOMU with minimal latency
Contribution to community
o Samsung will work to share Xen changes with community
o Some code is proprietary
11 © Samsung Electronics
Conclusion
Two Android can run with near-native graphics performance
Xen runs well on mobile devices
Using PV drivers, no major changes to Xen architecture required
Android is a trademark of Google Inc.
The Android robot is reproduced or modified from work created and shared by Google and used according to terms described in the Creative Commons 3.0 Attribution License.
Linux® is the registered trademark of Linus Torvalds in the U.S. and other countries.
ARM is a registered trademark of ARM Limited. Mali is a trademark of ARM Limited.
STAR WARS and related properties are trademarks in the United States and/or in other countries of Lucasfilm Ltd. and/or its affiliates. © 2012 Lucasfilm Ltd. All rights reserved.
Angry Birds is a trademark of Rovio Entertainment Ltd.
