下一站, android

下一站， AndroidJim Huang ( 黃敬群 /jserv)

From 0xlab - http://0xlab.org/

Dec 12, 2009

http://0xlab.org/

「下一站」到底有多遠？特立獨行的 Android ：相容性探討系統效能分析與評估功能層面的改進：以無線通訊為例

I/DEBUG ( 547): Build fingerprint: 'generic/sdk/generic/:1.5/CUPCAKE/148875:eng/test-keys'

I/DEBUG ( 547): pid: 732, tid: 746 >>> com.flexilis <<<

I/DEBUG ( 547): signal 11 (SIGSEGV), fault addr 00000002

I/DEBUG ( 547): r0 0000000b r1 00000000 r2 487ae000 r3 80000400

I/DEBUG ( 547): r4 00000002 r5 80000400 r6 001e6368 r7 00000000

I/DEBUG ( 547): r8 00000001 r9 4360d2f8 10 40008238 fp ad083e10

I/DEBUG ( 547): ip 00000002 sp 46319288 lr 00000004 pc ad01663c cpsr 20000010

I/DEBUG ( 547): #00 pc 0001663c /system/lib/libdvm.so

I/DEBUG ( 547): #01 pc 00016b78 /system/lib/libdvm.so

I/DEBUG ( 547): #02 pc 00014678 /system/lib/libdvm.so


I/DEBUG ( 547): #04 pc 000148ac /system/lib/libdvm.so

I/DEBUG ( 547): #05 pc 00016bc0 /system/lib/libdvm.so

I/DEBUG ( 547): #06 pc 0001535c /system/lib/libdvm.so

I/DEBUG ( 547): #07 pc 00047c94 /system/lib/libdvm.so

I/DEBUG ( 547): #08 pc 00058a16 /system/lib/libdvm.so

I/DEBUG ( 547): #09 pc 00042dba /system/lib/libdvm.so



I/DEBUG ( 547): #12 pc 000520ec /system/lib/libdvm.so

「下一站」到底有多遠？

DDMS 是您的好朋友

Dalvik heap, GC, call stack, log, intent/activity

特立獨行的 Android

GTK

FFmpeg

Linux Kernel

Glibc

Alsa

X11

CairoPangoOpenGL

SSL

在 Android中，您所熟悉的套件

Linux Kernel

OpenGL

SSL

都被取代了

Android的組成

glibc bionic→

Cairo Skia→

FFmpeg/GStreamer opencore→

ld.so linker→

Mesa3D/OpenGL

→ PixelFlinger + OpenGL|ES

init

(Dalvik)

砍掉重練不是壞事只是重新長出來的東西很不一樣

Android砍掉重練

glibc - OK!

bionic : 一連串的錯誤(非 POSIX相容 )

libc大不同

在 sys/cdefs.h 定義

gcc: mntent.h → features.h → cdefs.h

bionic: mntent → ???

兩邊的實作方式不一樣

libc大不同

Iptables, wireless-toolsglibc

#include <net/ethernet.h>bionic

#include <net/if_net.h>

glibc#include <sys/soundcard.h>

bionic#include <linux/soundcard.h>

ipv6glibc: /usr/include/netinet/in.hbionic: ???

沒有 getline, dprintf, vdprintf...etcVery limited support for SysV, POSIX

/usr/include/bits/socket.h

/* Type for length arguments in socket calls. */#ifndef __socklen_t_definedtypedef __socklen_t socklen_t;# define __socklen_t_defined#endif

bionic/libc/include/sys/socket.h

typedef int socklen_t;

這些都算小問題，雖然會增加移植的成本終究還是能夠解決

libc大不同

bionic/libc/docs/SYSV-IPC.TXT

Android does not support System V IPCs, i.e. the facilities provided by the following standard Posix headers:

<sys/sem.h> /* SysV semaphores */ <sys/shm.h> /* SysV shared memory segments */ <sys/msg.h> /* SysV message queues */ <sys/ipc.h> /* General IPC definitions */

The reason for this is due to the fact that, by design, they lead to globalkernel resource leakage.

這份文件第一次出現在 2009/02/19

(bionic)沒有 IPC的 shared memory

Linker 的設計沒有處理 weak symbol 遇到 weak symbol 便傳回錯誤的值

(bionic)linker/linker.c

系統效能分析與評估

SoC specific module (minimal efforts)

• libopencorehw.so (OpenCore HW module)http://gitorious.org/0xdroid/hardware_omap3_libopencorehw

• liboverlay.so (Graphics overlays module)

• libcamera.so (Camera HAL)http://gitorious.org/0xdroid/hardware_omap3_camera

• libaudio.so (Audio HAL)http://gitorious.org/0xdroid/hardware_alsa_sound

0xdroid provides the full source code of reference hardware acceleration modules for Android.

Performance Evaluation on Beagleboard

• TI OMAP3 SoC powered

• 500 MHz / ARM Cortex A8• 0xdroid – well-tuned Android for Beagleboard (TI

OMAP 3530)– http://code.google.com/p/0xdroid/

• Based on Android Donut branch– beagle-cupcake-0x2, beagle-donut-0x3

• Expertise in Android porting and performance tuning.

• Embedded CaffeineMark

• Dalvik VM : 1034• CVM + JIT : 7526

• Dalvik + bionic : CVM pure interpreter + glibc– Sieve → 950 : 351

– Loop → 775 : 329

– Logic → 1104 : 286

– String → 1898 : 3023

– Float → 772 : 298

– Method → 1032 : 286

Dalvik VM

[[ eclair + armv7 interpreter ]]

Sieve score = 956 (98)

Loop score = 783 (2017)

Logic score = 1099 (0)

String score = 2019 (708)

Float score = 819 (185)

Method score = 1103 (166650)

Overall score = 1069

Dalvik VMRefernce CaffeineMarkEmbedded results: (OMAP3530 at 500MHz)

[[ eclair + armv7 + jit ]]

Sieve score = 2345 (98)

Loop score = 3629 (2017)

Logic score = 5618 (0)

String score = 4328 (708)

Float score = 1495 (185)

Method score = 1954 (166650)

Overall score = 2907

但 JIT compiler不是萬靈丹， [x] 更大的記憶體開銷 (x2) [x] 較慢的應用程式啟動時間 [x] GC的非預期表現

Evalutions scenario: Introduced libopencorehw.so

(measured by utility “oprofile”)

Video playback :: Test Card Video (480x360, 25fps, H.264)

Evalutions scenario: Introduced libopencorehw.so


Video playback :: Action Video (480x360, 25fps, H.264)

Evalutions scenario: Introduced libcamera.so


Camera preview (320x480)

[[ very small data test ]]

memcpy_neon3 : (24 bytes copy) = 152.2 MB/s / 312.2 MB/s


memcpy_neon : (24 bytes copy) = 198.7 MB/s / 349.3 MB/s

memcpy_armv5 : (24 bytes copy) = 123.3 MB/s / 252.8 MB/s

memcpy_arm : (24 bytes copy) = 170.2 MB/s / 226.6 MB/s






[[ L1 cached data ]]











[[ very small data test ]]











- memcpy_neon3 : Eclair's NEON optimized - memcpy_neon2 : LGPL'd NEON optimized (version 2) - memcpy_neon : LGPL'd NEON optimized - memcpy_armv5 : donut/cupcake ARMv5 optimized - memcpy_arm : LGPL ARMv5 optimized

Memory operation tweaks

Dalvik, PixelFlinger, Skia

PixelFlinger JIT

optimized scanline_t32cb16

Reference benchmark on Beagleboard (TI OMAP353x) at 500 MHz

scanline_t32cb16_c memory bandwidth: 31.63 MB/s

scanline_t32cb16_neon memory bandwidth: 147.69 MB/s

It could dramatically improve boot animation performance.

NEON instructionsAdvanced ARM SIMD

PixelFlinger JIT

optimized t32cb16blend

Reference benchmark on Beagleboard 500MHz:

scanline_t32cb16blend_c memory bandwidth: 12.81 MB/s

scanline_t32cb16blend_arm memory bandwidth: 57.61 MB/s

scanline_t32cb16blend_neon memory bandwidth: 128.66 MB/s

scanline_t32cb16blend_c: generic C implementation.

scanline_t32cb16blend_arm: ARMv5 optimized by Android.

scanline_t32cb16blend_neon: ARMv7 tweaked implementation.

NEON instructionsAdvanced ARM SIMD

PixelFlinger JIT

00000077:03515104_00000000_00000000

(Blends a single color into an RGB565 buffer.)

Before: 27 inst/pixel, After: 24 inst/pixel, Improvement: 12.5%

00000077:03545404_00000A01_00000000

(Blends RGBA8888 texture into an RGB565 buffer using alpha.)


00000077:03545404_00000A04_00000000

(Blends RGB565 texture into an RGB565 buffer using alpha.)


UBFX instructionSigned and Unsigned Bit Field Extract. Copies adjacent bits

from one register into the least significant bits of a second register,and sign extends or zero extends to 32 bits.

PixelFlinger JIT

Code has been scheduled for A8 pipeline, specifically aiming to allow

multiplies to issue in pipeline 0, for efficient dual issue operation.

Testing on SpriteMethodTest (http://code.google.com/p/apps-for-android/) gives

8% improvement (12.7 vs. 13.7 fps.)

UBXTB16 instructionIntroducing the UXTB16 instruction allows removal of some maskingcode, and is beneficial from a pipeline point of view - lots of UXTB16

followed by MUL sequences.

功能層面的改進： Wireless

30

Android Power Management Architecture

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