User Guide

  • 2020
  • 05/04/2020
  • Public Content
Contents

Dialog Box: Custom Analysis

(One way) To access this
Intel Inspector
dialog box:
  • Click the
    Copy
    button on the
    Analysis Type-Memory Errors
    or
    Analysis Type-Threading Errors
    pane.
  • Click the
    Copy
    button or
    Edit
    button on the
    Analysis Type-Custom
    pane.
Use this dialog box to create or edit custom analyses .
Use This
To Do This
Analysis name
field
View or change the default name that distinguishes this custom analysis type from other analysis types when you use the graphical user interface.
Description
field
View or change the default detailed information that distinguishes this custom analysis type from other analysis types.
Command-line name
field
View or change the default identifier that distinguishes this custom analysis type from other analysis types when you use the command-line interface.
Analysis identifier
field
View or change the
{at}
identifier that distinguishes results produced by this custom analysis type from other results. For example:
ti2c
, where:
  • ti2
    represents the preset analysis type on which the custom analysis type is based
  • c
    represents custom

Configuration Settings for Custom Analysis Types Based on Memory Error Analysis Types

Use the
Properties
region of the dialog box to configure the custom analysis type.
The following table describes the purpose, usefulness, and
cost
(low, medium, high, or proportional in terms of time and resources) for each configuration setting in a custom analysis type based on a memory error analysis type. (The settings are listed in alphabetical order.)
Setting
Purpose, Usefulness, and Cost
Analyze stack accesses
Available only if
Detect invalid memory accesses
is selected.
Select to analyze invalid and uninitialized accesses to thread stacks.
Selecting is useful when:
  • You want as thorough an analysis as possible.
  • An application calls
    alloca()
    .
High
cost
.
Recommendation:
  • Select the first time you analyze an application and periodically thereafter.
  • Select to analyze automatic variables.
Defer memory deallocation
(previously called Byte limit before reallocation)
Available only if
Detect invalid memory accesses
and
Enable enhanced dangling pointer check
are selected.
Select to have the
Intel Inspector
prevent freed memory blocks from immediately returning to the pool of available memory.
Selecting is useful for discovering if an application tries to use memory after freeing it.
High
cost
if an application is performing many allocations/deallocations.
Recommendation: Select to improve analysis quality if the cost is not too high.
Detect invalid memory accesses
(split from Detect invalid/uninitialized accesses)
Select to detect problems where a read or write instruction references memory that is logically or physically invalid.
Selecting is useful to ensure an application accesses only valid memory.
Medium
cost
.
Recommendation: Select.
Detect leaks at application exit
(previously called Detect memory leaks upon application exit
)
Select to report typical memory leaks in which the application allocates a memory block, never releases it, and doesn’t keep a pointer to the block (e.g.
unreachable memory blocks
).
Selecting is useful when an application:
  • Runs out of memory.
  • Appears to be using more memory than expected.
Extremely low
cost
– especially if used only with
Remove duplicates
selected.
Recommendation: Select.
Detect still-allocated memory at application exit
(previously called Report still-allocated memory at application exit
)
Available only if
Detect leaks at application exit
is selected.
Select to report typical memory leaks in which the application allocates a memory block, doesn’t deallocate it, but a valid variable still holds a pointer to that block when the application ends (e.g.
reachable memory blocks
).
Cost
is proportional to the number of memory blocks still allocated when the application stops executing.
Recommendation: Select to investigate memory growth.
Detect uninitialized memory reads
(split from Detect invalid/uninitialized accesses)
Available only if
Detect invalid memory accesses
is selected.
Select to detect problems where a read instruction accesses an uninitialized memory location.
Selecting is useful when an application:
  • Exhibits unexpected behavior.
  • Shows evidence of uninitialized values in computations.
High
cost
.
Recommendation: Deselect.
Enable enhanced dangling pointer check
Available only if
Detect invalid memory accesses
is selected.
Select to detect if an application is trying to access memory after it was logically freed.
May be higher
cost
if an application is performing many allocations/deallocations, and the
Defer memory deallocation
list value is smaller than the amount of memory the application allocates.
Recommendation: Select when an application exhibits unexpected behavior you suspect may be caused by a dangling pointer.
  • Changes application behavior by intercepting calls to deallocators and deferring actual deallocation.
  • Enhanced dangling pointer check is not supported for
    new
    /
    delete
    and
    new[]
    /
    delete[]
    allocation/deallocation pairs.
Enable guard zones
Available only if
Detect invalid memory accesses
is selected.
Use in conjunction with
Guard zone size
to show offset information if the
Intel Inspector
detects memory use beyond the end of an allocated block.
Selecting is useful when:
  • An application exhibits unexpected behavior.
  • You need more context about heap allocations to interpret
    Invalid memory access
    problems.
Cost
is proportional to number of allocations.
Recommendation: Select unless:
  • Intel Inspector
    runs out of memory.
  • An application becomes destabilized.
  • May change application behavior.
  • Increases the amount of memory the
    Intel Inspector
    uses.
  • Intel Inspector
    creates guard zones only at the end of allocated space, not at the start of allocated space.
Enable memory growth detection
(previously called Enable interactive memory growth detection
)
Select to enable buttons in the GUI that let you send commands during application execution. This will show you a list of
reachable and unreachable memory blocks
for a time segment.
Selecting is useful for modeling memory usage patterns and ensuring a transactional application deallocates all memory allocations after a transaction completes.
Use in conjunction with the
Reset Growth Tracking
and
Measure Growth
buttons during analysis.
Low
cost
.
Enable on-demand leak detection
(previously called Enable on-demand memory leak detection
)
Select to enable buttons in the GUI that let you send “leak” commands. This will show you a list of
unreachable memory blocks
for a time segment.
Selecting is useful for checking for memory leaks in an application that never exits, or in only the portion of an application for which you are responsible.
Use in conjunction with the
Reset Leak Tracking
and
Find Leaks
buttons during analysis.
Cost
is proportional to the number of allocations.
Guard zone size
(previously called Guard zone byte size
)
Available only if
Detect invalid memory accesses
and
Enable guard zones
are selected.
Use in conjunction with
Enable guard zones
to set the number of bytes beyond the allocated block of memory the
Intel Inspector
reserves to identify
Invalid memory access
problems related to the allocation.
Setting is useful when:
  • An application exhibits unexpected behavior.
  • You need more context about heap allocations to interpret
    Invalid memory access
    problems.
Cost
is proportional to number of allocations.
Recommendation: Set unless:
  • Intel Inspector
    runs out of memory.
  • An application becomes destabilized.
  • May change application behavior.
  • Increases the amount of memory the
    Intel Inspector
    uses.
  • Intel Inspector
    creates guard zones only at the end of allocated space, not at the start of allocated space.
Maximum number of leaks shown in result
(previously called Maximum memory leaks)
Use to set the maximum number of leaks the
Intel Inspector
shows in a result after analysis is complete.
A zero setting shows all detected memory leaks.
Cost
is proportional to the number of leaks.
Recommendation: Use the default value unless you want an exhaustive list of all leaks.
Even the default value can generate an unmanageable number of leaks. Consider sorting the displayed memory leaks by
Object Size
, fixing the largest leaks, and then re-inspecting your application. Or use the on-demand leak detection feature to narrow your focus and eat the elephant one bite at a time.
Remove duplicates
Deselect to show all occurrences of a detected problem in the
Code Locations
pane.
Deselecting is:
  • Useful when you need to fully visualize all threads and problem occurrences in relation to time
  • Low
    cost
    in terms of time; however, the number of duplicate errors could crowd out the number of unique errors.
Recommendation: Select.
Revert to previous uninitialized memory algorithm (not recommended)
Available only if
Detect uninitialized memory reads
is selected.
The current algorithm for detecting uninitialized memory reads decreases false positives but increases analysis time and memory overhead. Select to use the previous version of the algorithm.
Recommendation: Deselect.
Stack frame depth
Use to provide more or less call stack context for detected errors.
A high setting is useful when analyzing highly object-oriented applications.
A higher number does not significantly impact
cost
.
Recommendation: Use only as large a value as an application requires to display complete call paths.

Configuration Settings for Custom Analysis Types Based on Threading Error Analysis Types

Use the
Properties
region of the dialog box to configure the custom analysis type.
The following table describes the purpose, usefulness, and
cost
(low, medium, high, or proportional in terms of time and resources) for each configuration setting in a custom analysis type based on a threading error analysis type. (The settings are listed in alphabetical order.)
Setting
Purpose, Usefulness, and Cost
Cross-thread stack access detection
Use to set the alert mechanism for when a thread accesses stack memory of another thread.
The alert mechanism helps you decide if this is an issue that requires handling.
All options are low
cost
if
Detect data races
is selected.
Recommendation:
  • Use
    Hide problems/Hide warnings
    if using an OpenMP* or Intel® Threading Building Blocks programming model; or if cross-thread stack accesses are anticipated. Also select
    Detect races on stack
    .
  • Use
    Hide problems/Show warnings
    if cross-thread stack accesses are not anticipated. Also deselect
    Detect data races on stack
    .
  • Use
    Show problems/Hide warnings
    if cross-thread stack accesses are not anticipated but a previous analysis indicated they exist and you are not using an OpenMP* or Intel Threading Building Blocks programming model. Also deselect
    Detect data races on stack
    .
Detect data races
Select to detect problems where multiple threads access the same memory location without proper synchronization and at least one access is a write.
Selecting is useful when you suspect data races that are not yet evident.
High
cost
.
Recommendation: Select. Consider also deselecting
Use maximum resources
to reduce cost.
Detect data races on stack
(previously called Detect data races on stack accesses)
Available only if
Detect data races
is selected.
Select to detect data races for variables allocated on the stack.
Selecting is useful when threads in an application share variables from the stack and you suspect data races on the variables.
High
cost
.
Recommendation: Deselect. If you select, consider also deselecting
Use maximum resources
to reduce cost.
Detect deadlocks
Select to detect problems where two or more threads are waiting for the other to release resources, but none of the threads releases the resources. Thus no thread can proceed.
Selecting is useful when you want to troubleshoot the location of a deadlock.
Low
cost
.
Detect lock hierarchy violations
Select to detect problems where the acquisition hierarchy order of multiple synchronization objects in one thread differs from the acquisition hierarchy order in another thread, and could cause a deadlock under certain conditions.
Selecting is useful when an application has complicated synchronization and it is hard to verify correctness.
Low
cost
unless an application has a significant number of locks.
Filter guaranteed atomics
Available only if
Detect data races
is selected.
Select to ignore data races on guaranteed atomic operations on the Intel® P6 processor family or newer. For details, please refer to the
Guaranteed Atomic Operations
section of the .
Selecting is useful if you observe many false data race reports on simple operations like Load or Store to shared variables and the size of those variables is less than the processor cache line size.
Do not select this option if you develop cross-platform code that should work on other architectures.
Selecting this option might also hide true-races on variables that were properly aligned during this run but might not be aligned in general, e.g., if it just works “by chance”.
Low
cost
.
Recommendations: Use this option with caution only if you observe many false reports on simple memory operations.
Race analysis byte granularity
(previously called Memory access byte granularity
)
Available only if
Detect data races
is selected.
Use to set the size of the smallest memory block the
Intel Inspector
considers a single block of memory when determining if non-synchronized accesses to a memory block constitute a data race.
Selecting is useful to control memory consumption during analysis for some applications.
High
cost
when set to 1 byte.
Recommendation: Set to 4 unless you continually see data races based on safe access to smaller memory blocks. If so, reset to 1.
Remove duplicates
Deselect to show all occurrences of a detected problem in the
Code Locations
pane.
Deselecting is:
  • Useful when you need to fully visualize all threads and problem occurrences in relation to time
  • Low
    cost
    in terms of time; however, the number of duplicate errors could crowd out the number of unique errors.
Recommendation: Select.
Save stack on first access
Available only if
Detect data races
is selected.
Select to show as much information as possible on all threads involved in a data race.
Selecting is useful when investigating complex data race problems.
High
cost
.
Recommendation: Deselect on initial analysis runs. Select only when you need the maximum information and context about all threads involved in a data race to solve the problem.
Save stack on lock creation
Select to show creation information on synchronization objects involved in deadlocks, lock hierarchy violations, and data races.
Selecting is useful when acquisition stacks are not sufficient to understand the problem.
Low
cost
.
Save stack on memory allocation
(previously called Save stack on allocation)
Available only if
Detect data races
is selected.
Select to identify the allocation site of dynamically allocated memory objects involved in data races.
Medium
cost
.
Recommendation: Select when you need to identify the object hierarchy of low-level objects involved in data races. For example: If object R is involved in a data race and is instantiated within objects O1, O2, and O3, the allocation call stack can help you identify which encapsulating object is not properly protecting access to object R.
Stack frame depth
Use to provide more or less call stack context for detected errors.
A high setting is useful when analyzing highly object-oriented applications.
A higher number does not significantly impact
cost
with one exception: Choosing a higher number plus selecting
Save stack on first access
increases
cost
.
Recommendation: Use only as large a value as an application requires to display complete call paths.
Terminate on deadlock
Available only if
Detect deadlocks
is selected.
Select to stop analysis and application execution if the
Intel Inspector
detects a deadlock.
Selecting is useful when running your application as part of a kernel or unit testing suite.
Low
cost
.
Recommendation: Deselect. Instead, use the corresponding knob in the command line interface to perform kernel or unit testing in a nightly scenario. If the
Intel Inspector
identifies a deadlock, decide if it is appropriate to continue analysis.
Use maximum resources
Select to potentially find more problems.
High
cost
.
Recommendation: Deselect to run a quicker analysis that should find most of your data race and cross-thread stack access problems. Once you have found and fixed these problems, select to get more complete analysis coverage of possible data race and cross-thread stack access problems.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804