Intel® Advisor User Guide

User Guide

Contents

Execution Speed/Duration/Scope Properties to Minimize Analysis Overhead

Issue

Running your target application with the
Intel® Advisor
 can take substantially longer than running your target application without the
Intel Advisor
.
Depending on an accuracy level and analyses you choose for a perspective, different overhead is added to your application execution time.
For example:
Runtime Overhead / Analysis
Survey
Characterization
Dependencies
MAP
Target application runtime with
Intel® Advisor
 compared to runtime without
Intel® Advisor
1.1x longer
2 - 55x longer
5 - 100x longer
5 - 20x longer

Solutions

Use the following techniques to minimize overhead while collecting
Intel Advisor
 analysis data. The
Disabling additional analysis
 technique also minimizes finalization overhead.

Change Stackwalk Mode from Offline (After collection) to Online (During Collection)

Minimize collection overhead.
Applicable analysis: Survey.
Set to offline/after collection when:
  • Survey analysis runtime overhead exceeds 1.1x.
  • A large quantity of data is allocated on the stack, which is a common case for Fortran applications or applications with a large number of small, parallel, OpenMP* regions
Note
: In the commands below, make sure to replace the
myApplication
 with your application executable path and name
before
 executing a command. If your application requires additional command line options, add them
after
 the executable name.
To implement, do one of the following before/while running a Survey analysis:
  • Set
    Project Properties
    Analysis Target
    Survey Hotspots Analysis
    Advanced
    Stack unwinding mode
    During collection
    .
  • Use the
    advisor
     CLI action option . For example: 
    advisor --collect=survey --project-dir=./advi_results --stackwalk-mode=online -- ./myApplication

Disable Stacks Collection

Minimize collection overhead.
Applicable analyses:
Characterization with Trip Counts and FLOP collections enabled
.
To implement, do one of the following before/while running the analysis:
  • Disable the
    Analysis Workflow
     pane
    > Characterization
    Collect call stacks
     checkbox.
  • Disable the
    Project Properties
    Analysis Target
    Trip Counts and FLOP Analysis
    Advanced
    Collect stacks
    checkbox.
  • Ensure the CLI action option is omitted from the command line. Alternative: Use the CLI action option
    --no-stacks
    .
    If you collected callstack-attributed data with
    collect.py
     or
    advisor
     (with
    --collect=tripcounts
    ), but callstack attribution went wrong, disable using callstacks data for analysis with
    analyze.py
     to avoid using the wrong data. This is a possible fallback when data with stacks is broken. Notice that this reduces modeling accuracy.

Disable Stitch Stacks

Minimize collection overhead.
Applicable analysis: Survey.
The stitch stacks option restores a logical call tree for
Intel® oneAPI Threading Building Blocks
 (
oneTBB
) or OpenMP* applications by catching notifications from the runtime and attaching stacks to a point introducing a parallel workload.
Disable when Survey analysis runtime overhead exceeds 1.1x.
Note
: In the commands below, make sure to replace the
myApplication
 with your application executable path and name
before
 executing a command. If your application requires additional command line options, add them
after
 the executable name.
To implement, do one of the following before/while running the analysis:
  • Disable the
    Project Properties
    Analysis Target
    Survey Hotspots Analysis
    Advanced
    Stitch stacks
    checkbox.
  • Use the
    advisor
     CLI action option . For example: 
    advisor --collect=survey --project-dir=./advi_results --no-stack-stitching -- ./myApplication
Disabling stack stitching may decrease the overhead for applications using
oneTBB
.

Increase Sampling Interval

Minimize collection overhead.
Applicable analysis: Survey.
Increase the wait time between each analysis collection sample when your target application runtime is long.
Note
: In the commands below, make sure to replace the
myApplication
 with your application executable path and name
before
 executing a command. If your application requires additional command line options, add them
after
 the executable name.
To implement, do one of the following before/while running the analysis:
  • Increase the value in the
    Project Properties
    Analysis Target
    Survey Hotspots Analysis
    Advanced
    Sampling interval
    checkbox.
  • Use the
    advisor
     CLI action option
    --interval=<integer>
     when running a Survey analysis. For example: 
    advisor --collect=survey --project-dir=./advi_results --interval=20 -- ./myApplication

Limit Collected Analysis Data

Minimize collection overhead.
Applicable analysis: Survey.
Decrease the amount of collected raw data when exceeding a size threshold could cause issues. For example: You have storage space limitations.
Note
: In the commands below, make sure to replace the
myApplication
 with your application executable path and name
before
 executing a command. If your application requires additional command line options, add them
after
 the executable name.
To implement, do one of the following before/while running the analysis:
  • Decrease the value in the
    Project Properties
    Analysis Target
    Survey Hotspots Analysis
    Advanced
    Collection data limit, MB
     field.
  • Decrease the value in the
    advisor
     CLI action option
    --data-limit=<integer>
    . For example: 
    advisor --collect=survey --project-dir=./advi_results --data-limit=250 -- ./myApplication

Limit Loop Call Count

Minimize collection overhead.
Applicable analysis: Dependencies, Memory Access Patterns.
Decrease the maximum number of instances each marked loop is analyzed.
Note
: In the commands below, make sure to replace the
myApplication
 with your application executable path and name
before
 executing a command. If your application requires additional command line options, add them
after
 the executable name.
To implement, do one of the following before/while running the analysis:
  • Supply a non-zero value in the
    Project Properties
    Analysis Target
    [Name] Analysis
    Advanced
    Loop Call Count Limit
     field.
  • Supply a non-zero value in the
    advisor
     CLI action option . For example: 
    advisor --collect=dependencies --project-dir=./advi_results --loop-call-count-limit=10 -- ./myApplication

Disable Additional Analysis

Minimize finalization overhead.
Applicable analysis: Survey.
Implement these techniques when the additional data is not important to you.
The default setting for all the properties/options in the table below is disabled.
Path: Project Properties
Analysis Target
Survey Hotspots Analysis
Advanced
CLI Action Options
Description
Disable the
Analyze MKL loops and functions
 checkbox.
Do not show
Intel® oneAPI Math Kernel Library
 loops and functions in
Intel Advisor
 reports.
Disable the
Analyze Python loops and functions
 checkbox.
Do shot show Python* loops and functions in
Intel Advisor
 reports.
Disable the
Analyze loops that reside in non-executed code paths
 checkbox.
Do not collect a variety of data for loops that reside in non-executed code paths, including:
  • Loop assembly code
  • Instruction set architecture (ISA)
  • Vector length
This capability is available only for binaries compiled using the
-ax
 (Linux* OS)
/Qax
 (Windows* OS) option with an Intel® compiler.
Disable the
Enable register spill/fill analysis
 checkbox.
Do not calculate the number of consecutive load/store operations in registers and related memory traffic.
Disable the
Enable static instruction mix analysis
 checkbox.
Do not statically calculate the number of specific instructions present in the binary.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.