Pane: Analysis Type-Memory Errors
 | Before Analysis (One way) To access this
Intel Inspector
pane:
Choose
. Then
choose
Memory Error Analysis from the
Analysis Type drop-down list.
Use this pane on the
Analysis Type window to:
During Analysis To access this pane: Click the
Analysis Type button on the
Navigation toolbar.
Use this pane to review the analysis type
settings for this analysis run.
After Analysis Is Complete To access this pane: Click the
Analysis Type button on the
Navigation toolbar.
Use this pane to:
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Use This
| To Do This
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|---|---|
Analysis Type drop-down list
| Switch to another category of analysis types.
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Configuration slider
| Choose a preset analysis type (drag slider).
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Analysis Time
Overhead gauge
 | Quickly estimate the time it may take to
collect a result using various preset analyses. Time is expressed in relation
to normal application execution time.
For example, 2x - 20x is 2 to 20 times
longer than normal application execution time. If normal application execution
time is 5 seconds, estimated collection time is 10 to 100 seconds.
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Memory Overhead gauge
 | The
Memory Overhead gauge helps you quickly
estimate the memory the
Intel Inspector
may consume to detect errors using this preset analysis type. Memory is
expressed in blue-filled bars.
The gauge does not show memory used by the running
application during analysis.
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Copy button
| Create a new custom analysis type based
on the currently selected analysis type.
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Analyze without debugger radio
button (Detect Memory Problems and
Locate Memory Problems analysis types
only)
| Select to run an analysis without launching an interactive debugging session. Useful for investigating all types of memory and threading problems.
You can later use the
Debug This Problem function from within a result to launch a new analysis in conjunction with a debugger to stop at problems of interest. The rerun analysis is automatically focused to find the selected problems, making it return to the problems more quickly. The
Debug This Problem function is the recommended method for investigating threading errors in an interactive debugging session.
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Enable debugger when problem
detected radio button (Detect Memory
Problems and
Locate Memory Problems analysis types
only)
| Select to allow investigation of every problem detected in an interactive debugging session. Useful for investigating all types of memory problems except memory and resource leaks.
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Select analysis start location with
debugger radio button (Detect Memory
Problems and
Locate Memory Problems analysis types
only)
| Select to allow investigation of problems in a particular area of code during an interactive debugging session. Typical scenario: You need to check for errors in a specific section of application code, but the
Intel Inspector does not provide the appropriate granularity to analyze only that code section. This option quickly takes you near that execution point in a debugging session. Useful for investigating all types of memory problems except memory and resource leaks.
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Configurable Memory Error Analysis Type Settings
The following list shows the configurable settings (in alphabetical
order) for preset memory analysis types.
Configurable
means you can change the setting without creating a
custom analysis type:
- Analyze stack accessescheckbox (configurable for theLocate Memory Problemsanalysis type only)
- Detect leaks at application exitcheckbox
- Detect still-allocated memory at application exitcheckbox
- Enable memory growth detectioncheckbox
- Enable on-demand leak detectioncheckbox
- Remove duplicatescheckbox (configurable for theLocate Memory Problemsanalysis type only)
- Stack frame depthdrop-down list
Memory Error Analysis Type Settings
Use the
Details
region to review current analysis type
settings. The following table describes the purpose, usefulness, and
cost
(low, medium, high, or proportional in terms of time and
resources) for each memory error analysis type configuration setting. (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:
High
cost .
Recommendation:
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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.
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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.
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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:
Extremely low
cost – especially if used only with
Remove duplicates selected.
Recommendation: Select.
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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.
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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:
High
cost .
Recommendation: Deselect.
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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.
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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:
Cost is proportional to number of allocations.
Recommendation: Select unless:
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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 .
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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.
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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:
Cost is proportional to number of allocations.
Recommendation: Set unless:
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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.
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Remove duplicates | Deselect to show all occurrences of a detected problem in the
Code Locations pane.
Deselecting is:
Recommendation: Select.
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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.
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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.
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