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Performance tuning in mobile devices
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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
Know your HWCPU/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: 2000~3500mAhLTE:
•下り~326Mbps 上り~86Mbps
•実効 ~60Mbps レイテンシ ~100msec
Saturday, July 26, 14
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
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
Demo: CPU throttling
Saturday, July 26, 14
Mobile Network
• 送らない
• Push通知
• ~128Byte以下
• Bulkで送る
A Close Examination of Performance and PowerCharacteristics of 4G LTE Networks
Saturday, July 26, 14
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