Optimization In Mobile Systems

Optimization & Performance Tuning in Mobile Systems,

Advanced Level

Raghu Sesha Iyengar

Agenda

Optimization What is optimization Why optimize When to optimize

Performance parameters Profilers Benchmark References

What is Optimization “The design and operation of a system or process to make it as

good as possible in some defined sense”. -- Wiktionary

“an act, process, or methodology of making something (as a design, system, or decision) as fully perfect, functional, or effective as possible; specifically: the mathematical procedures (as finding the maximum of a function) involved in this” – Merriam-Webster’s Online dictionary

Finding “best” route to Orchid – our definition

For software optimization, “as good as possible” generally means achieving a preset benchmark “defined” generally means parameters used to measure how close

we are to the most optimized state

What is Optimization

Optimization applies to all aspects of mobile system

Typical software architecture of a mobile phone (Android as an example)

Source:http://developer.android.com

Processor RAM Peripherals

HARDWARE

Why to optimizeMajor considerations of mobile phone software are: Portability

Multitude of hardware choices API, Protocols and Specifications

User experience Usability Performance (speed, memory, responsiveness) Look and feel

Functionality Phone or Supercomputer Reliability

Current drain Battery life Battery technology not catching up with growth in processor power

Security Software development time

Open Source Create differentiator software

Pitfalls of optimization Portability Repetitive process

Optimization is rarely a one-time process Change in hardware platform or Software framework can cause

optimization cycle to start Increasing processor power

Faster processors Coprocessors Hardware Accelerators

Unplanned time and effort Set your target

What is the optimal time to calculate the next move in a chess game? Open source or 3rd party code

A new drop may invalidate all your effort

When to optimize

Platform and framework Decisions

Compiler/Assembler Decisions Design

Optimize Code Code Optimize Design

Measure Parameters

Compare with Benchmark

Start

Stop Measured parameter values acceptable

Measured parameter values not acceptable

The Optimization Cycle

When to optimize

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Source: http://www.phonegg.com

Processor

Speed

Ram Internal

Memory

Display OS Camera

Droid 550MHZ 256MB 16GB 480x854px Android 5MP

HTC Nexus One

1GHZ 512MB 512MB 480x800px Android 5MP

iPhone 3GS 600MHz 256MB 16GB 320x480px MAC OS X 3MP

Nokia

N900

600MHz 256MB 32GB 800x480px Linux 5MP

Samsung

S8500 Wave

1GHz 512MB 2GB 480x800px Bada 5MP

LG Gw990 - - - 480x1024px MeeGo 5MP

Effort Returns

Low

Low

High

High

When to optimize Factors affecting CPU performance:

Co-processors & hardware accelerators

Advanced micro architecture (for same ISA)

Vector Registers Pipeline Optimizations

Data Forwarding Branch Prediction Predicate Register Delayed Branch

Cache Factors affecting Platform choice

Dev tools, IDE Target applications Support from vendor

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimizeKnow Thy compiler Optimization types

Programming language dependant Vs Programming language independent

Machine dependant Vs Machine independent

Optimization levels Dynamic and Static linking Prelinking Pragma Compiler options JIT

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimizeKnow Thy Framework Threading

• UI interactions• Background computations

File operation choices. • System calls for file op

• fopen Vs open• Write in standard chunks

• Background writes Algorithm choices

• Speed Vs Memory• Hash Vs Binary

• Analyze choices before optimizing• Spend enough time before picking

Create/destroy resources• Memory• peripherals

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize Other decisions

• Database decisions• Do we need database• Which data base to use

• Fixed Vs Floating point• Coding language decisions

• Application code• Native libraries

• API definitions• Extensibility

• Avoid costly Message passing• Sockets Vs Intents

• XML parser• SAX Vs DOM

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Know Thy language Strive for good programs not fast

ones Document optimizations

Optimization Vs Readability 80/20 rule. Area for compiler research Control flow optimizations

Implement state machines Optimization techniques for

Assembly Highly ISA dependent Group instructions Efficient loops Use MAC/FMA

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize High level language

Language dependent Lookup table Bounds checking Integer multiplication Dead code elimination Common sub expression

elimination Loop unrollingPlatform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Platform and framework Decisions

Compiler/Assembler Decisions

Design

Optimize Code Code Optimize Design

Measure Parameters

Compare with Benchmark

Start

Stop Measured parameter values acceptable

Measured parameter values not acceptable

The Optimization Cycle

Parameters for Optimization Speed Memory

Heap & Stack Image size

Response Time Launch time Response to user input

Current Drain Active Current drain Idle Current drain

Security Application Security Device Security Network Security

Profilers Speed Profilers

Based on how data is collected Event based (e.g., gcov, gprof’s number of calls etc, codewarrior, eclipse profiler) Sampling based (e.g., gprof’s runtime figures)

Based on amount of information provided Trace based (e.g., gcov) Statistical (e.g., AMD CodeAnalyst)

Based on instrumentation of code Manual (e.g., Eclipse TraceView) Automatic source level (e.g., CodeWarrior) Compiler assisted Binary instrumented

Memory Profilers Heap and Stack usage (e.g., Valgrind)

Profilers Response Time Profiler

Manual High Speed Camera setup

Current Drain Profiler Customized setup

Security Profiler Application security

FindBugs, Klocworks Device Security

Anti virus Network security

Netfilter

Appropriate IDEs From Vendor (e.g., CodeWarrior) Open Source (e.g., Eclipse, MOTODEV Studio, Carbide.C++)

Benchmarks

Internal Benchmarks Benchmark against another phone Benchmark against another similar application

External Benchmarks Industry Standard

Embedded Microprocessor Benchmark Consortium (EEMBC)

Standard Performance Evaluation Corporation (SPEC) Open Source

I/O intensive (IOMETER) CPU intensive (PI calculator, LINPACK)

ReferencesVarious Processors power dissipation detailshttp://en.wikipedia.org/wiki/List_of_CPU_power_dissipation

Summary of various processors based on different architectures:http://www.linuxfordevices.com/c/a/Linux-For-Devices-Articles/Embedded-Processor-and-SystemonChip-Quick-Reference-Guide/

openMPhttp://openmp.org/wp/

Boostpro libaries:http://www.boostpro.com

Vector signal processing libraryhttp://gpu-vsipl.gtri.gatech.edu/

Assembly and high level optimization techniqueshttp://www.agner.org/optimize/

Optimizing Java codehttp://www.glenmccl.com/jperf/index.htm

Optimization levels in GCC:http://www.linuxjournal.com/article/7269

Optimization levels in CodeWarriorhttp://www.freescale.com/infocenter/Codewarrior/index.jsp?topic=/com.freescale.doc.microcontrollers.targeting.manual/050_CWBuildProps.ColdFire_Compiler__Optimization.html

Profiler basicshttp://en.wikipedia.org/wiki/Profiling_%28computer_programming%29

Summary of profiling tools:http://ktown.kde.org/~seli/memory/analysis.html

Valgrind:http://valgrind.org/

Example codewarrior profilerhttp://www.freescale.com/files/soft_dev_tools/doc/user_guide/IDE_5.5_UG_Profiler.pdf

References

Kernel profile and OProfilehttp://omappedia.org/wiki/Android_Debugging

WinCE kernel profiler:http://discovertheexperience.blogspot.com/2009/02/windows-ce-kernel-profiler.html

iPhone Vs Android Development:http://blogs.zdnet.com/Burnette/?p=682&tag=col1;post-682

Low level optimization resourceshttp://www.agner.org/optimize/

Iphone securityhttp://www.itsecurity.com/features/iphone-security-threat/

Email securityhttp://www.itsecurity.com/email-security/

Jit: http://www.answers.com/topic/just-in-time-compilation

Assembly optimization tips:http://www.mark.masmcode.com/

Compiler, C++ optimization:http://www.agner.org/optimize/

Book on Software optimization:Software Optimization for High-Performance Computing By Kevin R. Wadleigh, Isom L. Crawford

Java benchmarkshttp://java-phones.com/tools/fpc-bench-303

Android benchmarks:http://mobileswdev.wordpress.com/2009/10/27/android-benchmarks/

Thank YouRaghu Sesha Iyengar

[email protected]

Mobile Developer Conference by

MoMoBhttp://momob.in

Additional Slides

When to optimize

Source: Software Optimization for high performance computingBy Kevin R. Wadleigh, Isom L. Crawford

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Source: Software Optimization for high performance computingBy Kevin R. Wadleigh, Isom L. Crawford

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Source: Optimizing Software in C++

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Source:http://www.linuxjournal.com/article/7269

Optimization Levels in GCC

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Source:http://www.linuxjournal.com/article/7269

Optimization Levels (gcc) -O0

No optimization -O1

Produce optimized image in short time -O2

All optimizations that do not cause space-seed tradeoff -Os

Size over speed optimization -O3

Optimize for best speed. Global optimization. Size increase expected.

Can have adverse effect if this size increase is more than cache size and leads to more memory access.

Use –f to use any option (which may not be included in the –ox) e.g., gcc finline-functions.

Use –fno to exclude. E.g., fcc –o1 –fno-defer-pop

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Source:http://reallylongword.org/prelink-2/

700MHz Athlon, 768MB RAM, Linux 2.4.21

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

A 100 MB file was read sequentially starting from the beginning of the file to produce these times. The file system buffer cache was 500MB

Source: Software Optimization for high performance computingBy Kevin R. Wadleigh, Isom L. Crawford

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High

When to optimize

Lookup Tables

Boundary checking

Source: Software Optimization for high performance computingBy Kevin R. Wadleigh, Isom L. Crawford

Platform and framework Decisions

Compiler Decisions

Design Optimization

Code Optimization

Effort Returns

Low

Low

High

High