01 intel vtune session 01

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Installing Windows XP Professional Using Attended Installation

Slide 1 of 24Ver. 1.0

Code Optimization and Performance Tuning Using Intel VTune

With the advent of high-end processing, computers with

lower memory and processing power have became

obsolete. Application performance did not improve

substantially even with upgraded hardware. As a result,

code tuning became a successful approach to get the best

performance from applications.

Code tuning involves optimizing the use of available

resources on the target platform and the source code or the

algorithm. It involves using Profilers to analyze the code and

performance analyzers/monitors to analyze the resource

usage.

This module deals with identifying the factors and areas that

affect the application performance. It deals with how to use

the tool to improve the application performance.

Why this module?


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In this session, you will learn to:

Identify the need for application optimization

Identify the application optimization process

Objectives


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The performance of an application depends on the:

Source code

Algorithm

Compiler

Computer architectureApplication optimization is the process of obtaining the best

performance from an application on a given hardware and

network specification.

The performance of an application can be improved by

making effective use of the available resources.

Exploring Application Optimization


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Application optimization:

Improves application performance

Leads to a better response time

Enables effective utilization of system resources

The following application areas require optimizationsignificantly:

Client/Server applications

Database-dependent applications

Scientific applications

Threaded applications

Exploring Application Optimization (Contd.)


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Client/Server applications:

Tend to be slow because various factors affect performance,

such as speed of execution at the client and server sides and

the speed of the connection.

Optimization options requires the following points to be taken

into account:

Identify the areas that decrease performance

Identify alternatives to optimize performance


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Database-dependent applications:

Are slow because database transactions take a substantial

amount of time

Takes a long time in searching and sorting records due to large

size of databases


into account:

The number of triggers fired with each transaction that occurs

The number of access to the database from the application

The number of records that the application fetches at a time for

processing


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Scientific applications:

Are used in real-time systems, such as weather forecasting,

aircraft engine automation, and radio electric power generation

Are mostly mission critical and involve many complex

calculations


into account:

Algorithm design

Compiler

Operating system

Processor architecture


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Threaded applications:

Can be used for lengthy processing and memory reads and

writes

Can be optimized by deciding the optimal number of threads

that are created for an application

The number of threads created also depends on the ability of the

processor and the operating system to handle multiple threads


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The performance of an application depends on computer

architecture, application design, and system resources.

As a result, you should analyze application performance at

three levels:

System levelApplication level

Microarchitecture level


Highest level of optimization Middle level of optimization Lowest level of optimization


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Optimization Level Optimization Goals Focus Areas Performance

Improvement Level

System Level Improving application

interaction with the

system

Network problems

Disk performance

Memory usage

Three times

improvement

Application Level Improving algorithms Data structuresFunction-calling

sequence

Threading algorithm

Two timesimprovement

Microarchitecture

Level

Improving application

interaction with the

processor

Data availability in

cache

Code availability in

cache

Data alignment

1.1-1.5 times

improvement


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Just a minute

Answer:

An application designed to take full advantage of the processor

by using multiple threads is called threaded application.

The performance of an application depends on computer

architecture, application design, and system resources.

What are threaded applications?

The performance of an application depends upon what all

factors?


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During optimization, you need to:

Identify optimization goals

Follow the appropriate optimization method

Stop the process when the desired level of optimization is

achieved

Identifying the Application Optimization Process


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Identifying the Application Optimization Process (Contd.)

The performance optimization process is an iterative cycle,

which consists of the following phases:

Gather performance data

Analyze data and identify performance issues

Generate alternatives to resolve issuesImplement enhancements

Test enhancements


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Gather PerformanceData

Test Results Analyze Dataand Identify Issues

ImplementEnhancements Generate Alternativesto Resolve Issues

Start HereIf the desired

level ofoptimization isnot achieved. If the desired level

of optimizationis achieved.

Stop


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Gather performance-related data for:

Processor utilization

Memory utilization

Time taken for execution

To gather performance-related data, you can:Use timing functions to calculate execution time

Use stop watch to measure execution time

Use performance analysis tool


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Analyze performance-related data to identify:

Hotspots

Bottlenecks

Bottlenecks can be:

Memory operationsMemory alignment

Floating point operations

System calls


Input/output (I/O) operations accessmemory to read or write data.As a result, the speed of I/O

operations is limited by the speed of

memory.

The time required to access the datadepends on how the objects and

variables reside in the memory. This is

called memory alignment.

Floating-point operations consumeboth space and time.

They increase the time and space

complexity.

System calls include input/outputoperations to disks, devices, and

operating systems.

During the non availability of theresources, processor might have to

wait, which further leads to

bottlenecks.


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Alternatives to resolve issues can be:

Optimizing memory operations

Optimizing floating point operations

Optimizing system calls


Accessing memory locations that are located at a distance

from each other will require more processor time and

might retard performance.

Therefore, write code that access memory sequentially.

The total number of floating-point operations must be

reduced as much as possible.

Data must be loaded in the memory before executing

instructions, so that the process need not wait for data.

Optimizing a floating-point operation might significantly

improve the program if it is used many times in the

application.

If you need only a small part of a service that the

operating system offers, you can build custom routines.

This is more efficient than loading the larger routines that

the operating system provides.


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Implement enhancements by:

Splitting bulky loops

Using optimal data structures

Minimizing the use of global data structures

Simplifying branchesPlacing the most likely branch first

Placing decision making constructs outside the loops



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Test enhancements to ensure that:

The results the optimized version computed are correct

The performance of the optimized version meets the desired

level



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What do you mean by hotspot?

Just a minute

Answer:

After collecting performance-related data, the data needs tobe analyzed. This analysis is the process of identifying areas

that take more time to execute. These areas are called

hotspots.


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Various optimizing tools help in analyzing the:

Application code usage

System level resource usage by the application

Commonly used tools are:

PerfmonJProfiler

VTune

Identifying the Tools for Performance Optimization


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Perfmon:

Used in Windows operating systems, such as Windows XP

Enables you to view the system level resource usage

JProfiler:

Is a Java profilerEnables you to view performance bottlenecks, memory leaks

and provides data related to the threading issues.

VTune:

Is a tool by Intel

Enables you to find the system resource utilization andexecution time taken by various modules or functions

Identifying the Tools for Performance Optimization (Contd.)


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In this session, you learned that:

Application optimization is the process of obtaining the best

performance from an application within the constraints of a

given set of hardware and network resources.

Applications that require performance optimization are:

client/server, database-dependent, scientific, and threadedapplications.

Application performance tuning can be performed at the

system, application, and microarchitecture levels.

Common performance issues include input/output operations,

floating-point operations, and system calls.

Summary


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Installing Windows XP Professional Using Attended InstallationCode Optimization and Performance Tuning Using Intel VTune

The performance optimization process consists of the following

five steps:

Gather performance data

Analyze data and identify issues

Generate alternatives to resolve issues

Implement enhancements

Test enhancements

Some of the commonly used tools and utilities to optimize

application performance are as follows:

Perfmon

JProfiler

VTune

Summary (Contd.)

01 intel vtune session 01

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