VOD SYSTEM ENGINEERING

Professor: Chon Kilnam Elton Kang 2006.6.16

TOPIC

Managing Battery Lifetime with energy-Aware Adaptation

Purpose

To achieve battery duration which user-specified

Dynamically balance energy conservation and application quality.

Extend battery life by as much as 30%-based on the paper

Energy-aware Adaptation

Method Dynamic balancing

Object Energy conservation & application quality

Integration is a must battery power hardware power requirements application mix user specifications

Power Scope

• Primary Purpose: Build energy-efficient software Simple and complex applications

• Impelmetation Statistical sampling profile the energy usage TWO stage process Data collection stage

(system activity+power consumption)

Data analysis is done offline

Power Scope

Implementation

Profiling computer (application executes) Data Collection computer Power Scope’s Two functions Data collection function

System Monitor (samples system activity) Program Counter, Program Identifier

Energy Monitor ( Colllecting data and storing current sample)

Energy analyzer use raw sample data to generate energy profile

System Monitor

Consists device driver Sample data User-level daemon process

Similar System monitorMORPH, DCPI

Using in-kernel circular buffer.

Power Scope API

• What is API ?Answer: applications to control profiling

Energy Monitor

What Energy Monitor do?1. Runs on data collection computer2. Configure multimeter to sample power usage of

profiling computer

Laptop measurementSample the current through external power source

Pocket computerProvide internal precision resistor

Energy Analyzer

Definitiongenerate an energy profile of system activity

Validation

Energy Cost Process Procedure

Platform Compaq ITSY V1.5 pocket computer (HP) IBM ThinkPad 560X laptop

Accuracy

Limitation1. Digital mulitimeter’s mesurement is not truly

instantaneous integration time (A/D converting time) Minimum 1.4micro sec

2. Capcitance of computer system included3. Delay between mulitimeter mesurement and

corresponding kernel sampling taking

8.04w

6.76w

In fig(a) multiplication instruction takes more than one cycle to execute that energy is spread out across multiple cycles

In fig(b) during10 microsecond exist higher power usage is because measurment is perterbed by the latency between time when measurment is taken and time when system monitor samples system activity on the profiling computer

Two ‘WHY’ is in figure a & b

Overhead

DefinitionSum of overhead of measuring power usage &using these measurements to predict energy demand

Impact additional energy consumption

IBM 560X laptop

Latency using Pentium cycle counter

Compaq Itsy

Getimeofday Linux system call

CPU overhead

CPU Overhead Pentium cycle counter

Linux Systemcall

Energy Overhead

1.0%

1.3%

Overhead at variable sampling rate

Energy-Aware Adaptation

Using Software design to impact system energy consumption Primary Goal: To change Fidelity affect application energy use Fidelity : an application-specific metric of quality

Application Dimention of fidelity

Video player Display size lossy compression in video stream

Map viewing program

Geographic feature

Methodology

Application used: Video Player Web Browser Speech Recognizer Map viewer

High Fidelity

Low Fidelity

Hardware power management

1 V

2 V V

3 V

4 V V

Sequence of measurement using baseline

Energy impact of fidelity (video)

Pessimetic

Idle is executing the kernel idle procedure- in Pentium( it’s hlt instruction)

Why Pessimetic?: by further efforts to reduce fidelity is quite impossible

Experimental Setup

IBM 560x SERVER

CPU 233MHZ 200MHZ

MEMORY 64MB 64MB

NETWORK INTERFACE 2MB/S 802.11

SAMPLING RATE(POWERSOCPE) 600SAMPLES /S

OS LINUX

VIDEO PLAYER

Video length and 5 levels of fidelity

Linear model’s coefficient of determination R2 >99%

Video Player

Description: Xanim Xanim fetch video data from server through Odyssey

and display on the client Support 2-D of fidelity: Lossy compression using resizing

display window size

ITSY V1.5 Result

Results for Itsy v1.5 StrongArm process Is weaker than Pentium

Ratio Reduction( fidelity, remote execution)

IBM 1.9 64-78%

ITSY 6.6 92-94%

Ratio is maximum and minimum power usage energy-aware adaptation more effective when ratio is HIGH !!!

Web Browser

DescriptionAdaptive Web browser Netscape Navigator

Web Browser

ResultUser needs some time after an image is displayed to absorb its contents. (Think time) here is 5s/image

Think time 5s

Web Browser

Baseline R2 91%

JPEG-50 R2 91%

JPEG-5 R2 91%

Web Browser

Concurrent execution affect energy usage

Depends on below three factors : Depend on application Application’s interleaving Machine on which the application runs

Web Browser

isolatio

n

con

curre

nt

Web Browser

FIGURE.17 ANALYSIS

Difference caused by concurrency and more energy is needed why?

Answer: concurrency reduces opportunities for powering down the network and disk

In the picture Wave LAN and Xsever is major issue Discussion Primary Goal : To yield significant energy savings

Discussion

Primary Goal :To yield significant energy savings

Method1: Lowering fidelity +Hardware Power Consumption

Method2: Concurrency Enhances Lowering Fidelity

Using method 1, 2 to Achieve Energy Conservation

Applications Summary

KEY MESSAGE:

Significant variation in the effectiveness of fidelity reduction across data objects

Considerable variation in the effectiveness of fidelity reduction across applications

Combining hardware power management with lowered fidelity can sometimes reduce energy usage below the sum of the individual reductions

.

Goal-Directed Adaptation

GOAL Energy-aware adaptation substantially reduce the

energy usage of mobile computers Goal-directed adaptation:

Use this information to direct application adaptation to meet a user-specified goal for battery duration

Parameter for battery lifetime: Display Brightness, Processor Speed, Device Timeout.

Tradeoff: quality & energy conservation

User and Application Interfaces

• Simple design Reference API:

Oddsey

register_fidelity

begin_fidelity_op

end_fidelity_op

240 minutes increase to 480 minutes (8 hours or more)

Determining Residual Energy

Smart Battery Using gas gauge chip Odyssey queries the Smart Battery by ACPI or machine-

dependent interface

Method Odyssey Calling

IBM 560XModulated energy

supplyioctl

ITSY DS2347ioctl

Predicting Future Demand

α is the gain , relative weight of current and past power usage

α is changing

tradeoff: agility and stability

GOAL α FIDELITY Adaptation Direction

Distance Increase Reduce Toward stability

Near Decrease Toward agility

Triggering Adaptation Predicted demand > Residual energy

increase fidelity Predicted demand <Residual energy

decrease fidelity Triggering condition: indicative of the level of hysteresis & supply >demand 5% of initial energy – variable : 1% of residual energy-constant

Energy Towards

Plenty Stability

Scarce Agility

DATA Analysis

0

20

40

60

80

100

120

140

1 2 3 4 5 6 7 8 9 10 11

CPUHardDisk

CPU and Harddisk power consumption

SOURCE: http://processorfinder.intel.com 2006.6.15

DATA Analysis

Advantage: Flash memory Reduce Power consumption Dramatically!!! 5% of Consumption Read/Write access time

3x Read speed as fast as Harddisk (53MB/s) 1.5x Write speed as fast as Harddisk(28MB/s)

Order of Power consumption in Flash disk drops from 100 to 10

Disadvantage: Expensive with same storage size

DATA Analysis

CPU and Flash Memory power consumption

0

20

40

60

80

100

120

140

1 3 5 7 9 11

CPUFLASH

Source: http://www.eetkorea.com 2006.5.29

Delivery

VOD system architecture

CPUUSB

DISPLAY

FLASH

DDR

AUDIO

VIDEO

DDR

System Block Diagram

Syste

m B

us

Video InputInterface

Video Processor

FLASH Interface

AudioProcessor

LMI

EMI

Network

HARDDISK

Issue List

Duo or more CPUs with Flash Memory How about more cores and more flashes.. CPU Bottleneck issue Power consumption calculation only used one Core Parallel processing & Multicore Harddisk and Flash Memory’s Price Issue

Issue List Solution

Duo or more CPUs with Flash Memory CPU Bottleneck issue

Solution:Direct Connect Architecture

Bottlenectk No Bottleneck

Issue List Solution

How about more cores and more flashes?Power consumption calculation only used one Core

Solution: In Intel CPU one core and two cores CPU does not varies too much in TDP(Thermal Design Power).That means more cores bring more power consumptionis Myth.This VOD system uses two cores without any problem, but 3 or More cores that’s another parallel processing issue.(Further Study Issue)

Issue List Solution

Parallel processing & MulticoreSolution:Due to architecture of CPU and system

parallel is soft technology and multicore is hardware based technology.

In this system , I implemente with multicore and using parallel processing to satifying the video in the foreground and sound player and vaccin program running in the background.

That is to say, using multicore solution to reduce the CPU bottleneck issue to lower down the overhead and reduce the power consumption and parallel processing to complete software control to power consumption.

(Further study topic, 3 cores with parallel processing CPU resource allocation)

Issue List Solution

Harddisk and Flash Memory’s Price Issue

Solution: This VOD system is state-of-art technology

implementation and the disadvantage is more expensive than current model, due to flash memory price. So This system interface with flash memory and extends for harddisk.

For price issue, harddisk is considered into optionial choice.

But harddisk is just for big data storage, without that specific task it is in idle mode. Power consumption is 30% of normal harddisk’s consumption. Saves up to 70% or more.

ReferenceProblem Solving (hard copy)Managing Battery Lifetime with Energy-Aware Adaptation

(parts of textbook)Patterns of Problem Solving( Textbook)Complexity (Textbook)

http://processorfinder.intel.com

http://eetkorea.co.kr

Operating System -2nd edition (Textbook)

Computer Architecture (Textbook)http://www.intel.comhttp://www.dataquest.comhttp://www.st.com

ISO 14496 (MPEG-4 part.10)specification http://www.divx.org (H.264)