04 intel v_tune_session_05

During this session you will learn to:
Identify the features of VTune Performance Analyzer
Identify hotspots and bottlenecks in an application using
sampling
Objectives

VTune Performance is a powerful and easy-to-use software-
analysis tool.
It collects, analyses, and displays performance data for a
wide variety of applications.
It can be used to identify and locate the code snippets in your
application that show the highest amount of activity over a
specific period.
It also displays how an application interacts with the OS or
other software, such as drivers.
Exploring VTune Performance Analyzer

Various features of VTune Performance Analyzer are as
follows:
Sampling
Call graph
Counter monitor
Tuning assistant
Hotspots view
Features of VTune Performance Analyzer
Calculates the actual performance of
the system over a period and for
various processor events
►
Provides a graphical view of the flow of
an application and helps you identify
critical functions and timing details in the
application
►
Provides system-level performance
information, such as resource
consumption, during the execution of an
application
►
Provides tuning advice from an analysis
of the performance data. The tuning
advice helps you improve performance of
an application
►
Helps identify the area of code that takes
the maximum CPU time
►

VTune Performance Analyzer provides flexible user
interfaces.
Using these interfaces, you can manage and organize various
windows and analyze views, according to your requirements.
Working With VTune User Interface

Working With VTune User Interface (Contd.)
Tuning browser: The Tuning Browser window displays a
list of the contents of a project. This window enables you to
view the result of activities. The Tuning Browser window
also enables you to use all the activities related to the
project.
Output window: The Output window displays messages
during data collection and analysis.
Data view: Data views display analysis data in various
formats.
Menus and toolbars: Menus and toolbars provide easy
access to the common commands of the VTune
Performance Analyzer. Using these commands, you can
access the information that the VTune Performance
Analyzer provides.

Which data view displays all the threads that run within a
selected process?
Which data view enables you to pinpoint problem areas in
the code?
Just a minute
Answer:
Thread view
Source view

Identifying Wizards in VTune
The different wizards available in VTune Performance
Analyzer are displayed in the following table.
Name Description
Quick Performance Analysis
(QPA) wizard
It enables you to quickly analyze your application's performance.
This wizard enables you to create an activity with any combination of
sampling, counter monitor, and call graph collectors.
Complete setup wizard It enables you to create an activity and configure multiple collectors
at the same time. The wizard prompts you to enter values only for
the basic parameters and uses default values for others.
Counter monitor wizard It enables you to create an activity and configure the counter monitor
data collector. The wizard prompts you to enter values only for the
basic parameters, and uses default values for others.

Identifying Wizards in VTune (Contd.)
Name Description
Sampling wizard It enables you to create an activity and configure the sampling collector
to profile any type of application. The wizard prompts you to enter
values for the basic parameters and uses default values for others.
Call graph wizard It enables you to create an activity and configure the call graph data
collector to profile any type of application. The wizard prompts you to
enter values for the basic parameters and uses default values for
others.
Advanced Activity
Configuration wizard
It enables you to control all the steps of activity creation and
configuration.
You can add multiple data collectors and configure them. You can also
add application/module profiles to an activity and associate them with
any of the data collectors.
Use the Advanced Activity Configuration option offers more flexibility in
activity creation.
The different wizards available in VTune Performance
Analyzer are displayed in the following table.

Using Sampling
Sampling is the process of collecting a set of data for analysis
and representing the analyzed data in statistical format.
Sampling enables you to:
Identify hotspots
Identify bottlenecks
Hotspot is the section of code
that takes a long time to
execute.
It consumes a large amount of
processor time.
►
Bottleneck is the area of code
that slows down the execution
of the application.
All bottlenecks are hotspots but
all hotspots are not bottlenecks.
►

When you perform an activity by using time-based
sampling, the VTune Performance Analyzer:
Executes the application you have launched
Stops the processor at the sampling interval and collects
samples of the specified application
Stores sampling data in the buffer. When the buffer is full, it
stops sampling. The VTune Performance Analyzer then writes
the sampling data to the disk and resumes sampling
Continues to collect sampling data until the specified
application terminates or the specified sampling duration ends
Analyzes the collected data, creates an activity result in the
Tuning Browser window, and displays the total data collected
for each module
Using Sampling (Contd.)

Event Based Sampling (EBS) is performed on the processor
events.
EBS enables you to determine which process, thread,
module, function, or code line in the application is generating
the largest number of processor events.

Sampling over time view shows the threads running during
data collection.
It displays the samples collected with respect to time for a
single event.

You can use the Over Time view to gather the following
information:
Context switching: Enables you to determine if there is
excessive context switching
Processor utilization: Enables you to identify which processors
are idle at what times
Temporal location of hotspots: Enables you to view the
specific periods of time when a large number of events occurred
Thread interaction: Enables you to view the number of threads
in an application but not how they interact with each other

Which wizard in sampling allows you to create an Activity
and configure the sampling collector to profile any type of
application?
Just a minute
Answer:
Sampling wizard

Problem Statement:
John has created an application in Java which involves the use of
a two-dimensional matrix. However, he finds that his application
takes a long time to execute. Therefore, John decides to analyze
the performance of the application using the event-based
sampling (EBS) feature of VTune Performance Analyzer. Help
John accomplish this task.
Activity: Performing Event-Based Sampling – 1

Solution
To analyze the performance of the application using EBS, you
need to perform the following tasks:
1. Configure EBS using the Sampling wizard.
2. Analyze sampling results.
Activity: Performing Event-Based Sampling – 1 (Contd.)

In this chapter, you learnt that:
Intel VTune Performance Analyzer is a powerful and
easy-to-use software-analysis tool.
VTune Performance Analyzer helps you identify and locate the
area of code in an application that shows the highest amount of
activity over a specific period.
VTune Performance Analyzer displays how an application
interacts with the OS or other software.
VTune Performance Analyzer provides a number of features,
which make it an efficient performance analysis tool. The
features are:
Sampling
Call graph
Counter monitor
Tuning assistant
Hotspots view
Summary

VTune Performance Analyzer provides flexible user interfaces to
manage and organize different windows.
Sampling is a process of collecting and testing a set of data for
relevant information and presenting the analyzed data in
statistical format.
Sampling helps you:
Identify hotspots
Identify bottlenecks
VTune Performance Analyzer provides two types of sampling
mechanisms to collect data. They are:
Time-based sampling (TBS): In TBS, the VTune Performance
Analyzer collects samples of an activity at regular intervals of
time.
Event-based sampling (EBS): In EBS, the VTune Performance
Analyzer collects samples of an activity at regular intervals of
processor event.
Summary (Contd.)

04 intel v_tune_session_05

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