07 intel v_tune_session_10

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Code Optimization and Performance Tuning Using Intel VTune
In this session, you will learn to:
Use the Tuning Assistant
Objectives

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Tuning assistant is a tool that provides with information that
enables you to tune the performance of your application and
the way it uses system resources.
Using Tuning Assistant

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Once the optimization goals are clear, you can tune your
application at the following three levels:
System-level tuning
Application-level tuning
Microarchitecture-level tuning
Understanding the Tuning Methodology

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System-level tuning:
Helps in optimizing the utilization of system resources.
Speeds up the performance of the application by improving the
way application interacts with the system.
Is significant for input/output (I/O) intensive applications. The
performance of these applications depends on the
performance of the I/O system that provides the I/O service.
Can be achieved by using the counter monitor feature of
VTune Performance Analyzer.
Understanding the Tuning Methodology (Contd.)

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Application-level tuning:
Helps in reducing the execution time of an application.
Can be performed by improving the algorithms of the
application, implementing threads, and by using Application
Programming Interfaces (APIs) and primitives.
Can be achieved by identifying the code snippets that have a
high impact on the performance of the application.
Helps in identifying the code snippets by using the sampling or
call graph feature of the VTune Performance Analyzer.

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Microarchitecture-level tuning:
Increases the performance of an application by improving the
way an application runs on the processor.
Can be used with processor-intensive applications
If an application is not processor-intensive, then you should first
improve processor utilization by using system-level and
application-level tuning.
Can be achieved by using the sampling feature of VTune
Performance Analyzer.

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Just a minute
Which level of tuning methodology will you use for
I/O-intensive application?
Which level of tuning methodology will you use for a
process-intensive application?
Which level of tuning methodology will you use to reduce
the execution time of an application?
Answer:
System-level tuning
Microarchitecture-level tuning
Application-level tuning

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It is a good practice to start tuning an application at the
system-level to avoid any system-level bottlenecks.
Once you ensure that the processor utilization is high, then
you can focus on removing the application-level bottlenecks
followed by microarchitecture-level bottlenecks.
If you are not sure about the specific goals, then you should
follow the following sequence in order to achieve the best
performance of an application in the shortest possible time:
System-level
Application-level
Microarchitecture-level
Tuning Methodology for Specific Goals

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There are three main strategies to improve the performance
of an application.
Each strategy affects processor utilization in a different way:
Balancing I/O and computation
Improving the threading model
Improving the efficiency of computation
Tuning Methodology for Specific Goals (Contd.)
►
This strategy enables you to speed up the
application when the processor utilization is
low.
In this case, you need to make changes at
the system-level and the application-level.
►
This strategy enables you to:
Add multithreading to a single threaded
application
Improve the threading model of a
multithreaded application
It enables you to make effective use of
system resources.
In this case, you need to make changes at
the application-level.
►
This strategy enables you to speed up the
application by accomplishing the same amount of
work using less computations.
In this case, you need to make changes at the
application-level and microarchitecture-level

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Tuning assistant:
Helps you to get more insight into the performance issues in an
application and identify the hotspots where performance can
be improved.
Provides you with the possible solutions to remove or avoid a
performance issue.
Provides tuning advice for codes, processes, or time ranges
that you select in the source, sampling, or counter monitor
views.
Launching Tuning Assistant

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The different types of advice that tuning assistant can
provide are:
Sampling-based advice
Counter monitor-based advice
Source-based tuning advice
Static assembly penalties
Launching Tuning Assistant (Contd.)

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Activity: Launching the Tuning Assistant
Problem Statement:
Chris has developed an application in C# that creates a list of
natural numbers and displays their sum. However, on
execution, the application runs very slowly. To analyze
performance of his application, Chris decides to analyze his
application using the counter monitor feature of Intel VTune
Performance Analyzer and use Tuning Assistant to identify the
performance issues and propose possible solutions for the
issues. Help Chris perform the required task.

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Activity: Launching the Tuning Assistant (Contd.)
Solution
To analyze counter data and use Tuning Assistant to identify
system-related performance issues and propose possible
solutions for the issues, you need to perform the following
tasks:
1. Collect counter monitor data.
2. Launch Tuning Assistant.

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Activity: Launching the Tuning Assistant (Contd.)
Solution
The information that tuning assistant provides are as follows:
Insight
Relevance scale
Tuning assistant advice
Workload

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In this session, you learned that:
The Tuning Assistant tool of VTune Performance Analyzer
tunes the performance of applications.
You can tune the application at the following three levels:
System-Level tuning
Application-Level tuning
Microarchitecture-Level tuning
It is a good practice to start tuning an application at the system
level instead of microarchitecture level.
Three main strategies to improve the performance of an
application are:
Balancing I/O and computation
Improving the threading model
Improving the efficiency of computation
Summary

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The tuning assistant helps you to get more insight into the
performance issues in an application and identify the hotspots
where performance can be improved.
The different types of advice that Tuning Assistant can
generate are:
Sampling-based advice
Counter monitor-based advice
Source-based tuning advice
Static assembly penalties
Summary

07 intel v_tune_session_10

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07 intel v_tune_session_10