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XPDS13: Dual-Android on Nexus 10 - Lovene Bhatia, Samsung


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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.

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XPDS13: Dual-Android on Nexus 10 - Lovene Bhatia, Samsung

  1. 1. Dual-AndroidTM on Nexus 10 Samsung Research UK Presentation for Xen Developer Summit 24-25 Oct 2013 Edinburgh, UK 10/21/2013 © Samsung Electronics 1
  2. 2. Introduction  Feasibility: 2 copies of Android on Xen on ARM? o Xen on mobile performance? o Virtualized GPU required  Nexus 10 device used o o o o CPU: ARM Cortex A15 (x2) GPU: ARM Mali T604 Memory available: 2GB RAM, plenty of Flash Screen resolution: 2560x1504 © Samsung Electronics 2
  3. 3. Configuration  Software configuration – 2 VMs only o o o o DOM0 = 1st Android DOMU = 2nd Android Linux 3.4 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 SMP I/O © Samsung Electronics Dual-core DOMU kernel 1GB RAM Memory DOM0 kernel 1GB RAM Dual-core Single-core Pass through PV Drivers 3
  4. 4. Xen PVH Architecture DOM0 DOMU Android Apps Android Apps Android Jelly Bean 4.2 Linux 3.4 User (PL0) Kernel (PL1) Android Jelly Bean 4.2 Linux 3.4 Physical Drivers HYP (PL2) HW Back End Drivers Rings Front End Drivers Xen on ARM Display, Touch etc. © Samsung Electronics GPU Mali T604 CPU 0 (Cortex A15) CPU 1 (Cortex A15) 4
  5. 5. 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 © Samsung Electronics 5
  6. 6. Video  Demo video o o o o Switching between Android  Icon or Volume key Angry Birds in DOMU  Near-native performance of PV drivers Angry Birds in DOM0 and DOMU concurrently  Two independent Android 3D Benchmark clip DOM0 – Blue Wallpaper Passthrough drivers DOMU – Orange Wallpaper PV Drivers Switching icon © Samsung Electronics 6
  7. 7. 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 Composition frame buffers 0 1 2 App frame buffers 0 1 2 0 © Samsung Electronics 15 30 45 60 time (ms) 7
  8. 8. Results Dual-Android, GPU composition 70 160 60 140 FPS 100 40 80 30 60 20 Packets/sec (k) 120 50 40 10 20 0 0 DOM0 © Samsung Electronics DOMU Packets/sec (k) 8
  9. 9. Event Channel Under Stress  DOMU Vsync arrival time delta Delta Time (ms) 35 Some missed events 30 25 20 16.67 15 10 5 0 10 11 12 13 14 15 16 Benchmark Time (sec) © Samsung Electronics 17 18 19 20 9
  10. 10. 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 © Samsung Electronics 10
  11. 11. 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. © Samsung Electronics 11