Performance tuning in mobile devices

1. Mobile 機器の
パフォーマンス最適化
Hakuro Matsuda
@hak / hakuroum@gmail.com
Saturday, July 26, 14

2. 最適化のゴール
• Better UX
• Smooth animation
• 60FPS の達成
• Quicker response time
• Longer Battery life
• (Richer contents)
Saturday, July 26, 14

3. Know your HW
CPU/GPU: Cortex-A15 相当 2~4 コア + モバイル GPU
• 100~300 GFLOPS
RAM:1GB~3GB
• LPDDR3/DDR3L 帯域 6.4GB/s~17GB/s
Screen: 1080p~WQXGA(2560x1600)
• 240~480dpi
Battery: 2000~3500mAh
LTE:
• 下り~326Mbps 上り~86Mbps
• 実効 ~60Mbps レイテンシ ~100msec
Saturday, July 26, 14

4. バッテリー消費
• Radio
• LCD
• CPU/GPU
Suspended State
(68 mW)
Video Playback
(450 mW + backlight)
Android G1 energy consumption
“An Analysis of Power Consumption in a Smartphone”, USENIX 2010
Saturday, July 26, 14

5. Variable CPU Cycles
• 可変クロックレート
• CPU governor
• Thermal Throttling
• CPU load throttling
• 300 Mhz ~2.3 Ghz (N5) http://arstechnica.com/gadgets/2013/11/
when-benchmarks-arent-enough-cpu-performance-in-the-nexus-5/
Saturday, July 26, 14

6. Demo: CPU throttling
Saturday, July 26, 14

7. Mobile Network
• 送らない
• Push通知
• ~128Byte以下
• Bulkで送る
A Close Examination of Performance and Power
Characteristics of 4G LTE Networks
Saturday, July 26, 14

8. まとめ
• 携帯電話機の HW 特性について
• Android NDK を使った Low level 最適化
について(追加テスト中で資料略)
• C++11 rocks!!
Saturday, July 26, 14