Suitability Report Overview
After the Suitability tool
runs your program's target executable to collect data, the
Suitability Report
window appears. It displays the approximate predicted performance based on its analysis of the annotated parallel sites and tasks.

This screen shows data based on a
Target System
of
CPU
. The screen shown on your system will differ.
![]() | The upper-left area shows the
Maximum Program Gain for All Sites in the program. Your overall goal of adding parallelism is to increase the
Maximum Program Gain for All Sites so the parallel program will execute as fast as possible. The measured serial execution runtime, predicted parallel runtime, and any measured
are displayed below
Maximum Program Gain for All Sites . Use the predicted Suitability gain values to help you make informed decisions about where to add parallelism.
If the Suitability tool detects any annotation-related errors, they appear at the top of the
Suitability Report window. If you see this type of error, the displayed Suitability data may not be reliable. Annotation-related errors may be caused when the correct sequence of annotations do not occur because of missing annotations, when unexpected execution paths occur, or if Suitability data collection was paused while the target was executing.
|
![]() | Use the upper-right row of
to model performance. Choose a hardware configuration and threading model (parallel framework) values from the drop-down lists. If you select a
Target System for
Intel® Xeon Phi™ processors, an additional value for total
Coprocessor Threads appears.
Below this row is a grid of data that shows the estimated performance of each parallel site detected during program execution. The
Site Label shows the argument to the site annotation. Examine the predicted
Site Gain and
Impact to Program Gain (higher values are better) to estimate how much each site contributes to the
Maximum Program Gain for All Sites for all sites (described above). To expand the data under
Combined Site Metrics or
Site Instance Metrics , click the
![]() ![]() To view source code for a selected parallel site, click its row to display the
Suitability Source window.
To show or hide the side command toolbar, click the
![]() ![]() |
![]() | The
Scalability of Maximum Site Gain graph summarizes performance for the selected site. The number of CPU processors or total number of coprocessor threads appears on the horizontal X axis and the target's predicted performance gain appears on the Y axis. To change the default
CPU Count and the
Maximum CPU Count , set the Options value.
If you choose a
Target System of
CPU , to view detailed characteristics of the selected site as well as its tasks and locks, click the
Site Details tab.
|
![]() | Use the
Loop Iterations (Tasks) Modeling (or
Tasks Modeling )
to experiment with different loop structures, iteration counts, and instance durations that might improve the predicted parallel performance.
For example, you might want to see the impact of modifying your nested change loop structure, modify the loop body code, or change number of iterations.
If the task annotations indicate likely
task parallelism, the title will appear as
Task Modeling (instead of
Loop Iterations (Task) Modeling for data parallelism).
|
![]() | Use the
Runtime Modeling to learn which parallel overhead categories might have an impact on parallel overhead. If you agree to address a category later by using the chosen parallel framework's capabilities or by tuning the parallel code after you have implemented parallelism, check that category.
If the chosen
Target System is
Intel Xeon Phi or
Offload to Intel Xeon Phi , additional
options appear below the
Runtime Modeling area. To expand this area, click the down arrow to the right of
Intel Xeon Phi Advanced Modeling .
|
![]() | Below the graph is a list of issues that might be preventing better
predicted performance gains as well as a summary of serial and predicted parallel time. To expand a line, click the down arrow to the right of the item's name. Most issues are related to the
Runtime Modeling . Later, you can use other Analyzer tools like
to measure
actual performance of your parallel program.
|
Target System Hardware Configurations
The
Target System
lets you select the type of hardware configuration to be analyzed. From this drop-down list, you can check each type to learn the likely predicted performance characteristics for each:
- CPUshows the predicted performance of only the CPU. Choose this item forIntel® Xeon®or similar processors that do not have significantparallel coprocessors. For anIntel® Xeon Phi™processor, choose this setting to only model the host processor, such as anIntel Xeonprocessor. If you choose this configuration, you can specify theCPU Countmodeling parameter.
- Intel Xeon Phishows the predicted performance when using only theIntel Xeon Phicoprocessor cores, and not the host processor. This parameter does not account for data exchange amongstIntel Xeon Phicoprocessor cores and the host CPU. If you choose this configuration, you can specify theCoprocessor Threadsmodeling parameter.
- Offload to Intel Xeon Phishows the predicted performance when usingIntel Xeon Phicoprocessor manycores to execute parallel code after the host CPU starts the program and before execution resumes on the host CPU for program completion. If you choose this configuration, you can specify theCoprocessor ThreadsandCPU Countmodeling parameters.
Data Displayed When the Target System is
Intel® Xeon Phi™
Intel® Xeon Phi™
A sample screen below shows changes in orange boxes when the
Target System
is
Intel Xeon Phi
(instead of
CPU
).

- The displayed data changes, such as theMaximum Program Gain for All Sitesand the serial and predicted parallel time.
- The graph's appearance changes to a gray-green color and the X axis displaysCoprocesser Threads(instead ofCPU Count) to represent the predicted performance of the manycore parallel coprocessor. This graph shows the predicted parallel performance of the manycore parallel coprocessor without accounting for data exchange amongstIntel Xeon Phii coprocessor cores and the host CPU. For many applications, the number of task instances does not scale enough to fully utilize the many cores of the parallel coprocessor, as indicated by a hover tip. Applications that are not appropriate for aIntel Xeon Phiprocessing system have values that appears in the gray part of the graph; in this case, try modeling other types of theTarget System.
- The lines between the graph's gray and green areas is a reference baseline, where the reference CPU chosen to calculate theIntel Xeonprocessor peak baseline is a dual-socket 8-coreIntel Xeonprocessor E5-26xx product family (2.7 GHz, 16 cores total). When theMaximum Site Gainexceeds this baseline, you might consider using anIntel Xeon Phicoprocessor rather than anIntel Xeonor similar processor.When theTarget Systemis eitherIntel Xeon PhiorOffload to Intel Xeon Phi, theIntel Xeon Phi Advanced Modelingoptions appear. SeeIntel® Xeon Phi™Advanced Modeling.
Data and Modeling Parameters When the Target System is Offload to
Intel Xeon Phi
Intel Xeon Phi
A sample screen below shows changes in orange boxes when the
Target System
is
Offload to Intel Xeon Phi
(instead of
CPU
) and the
Offload to Intel Xeon Phi
column is selected.

When you select a
Target System
of
Offload to Intel Xeon Phi
coprocessor:
- The displayed data changes, such as theMaximum Program Gain for All Sitesand the serial and predicted parallel time.
- An additional modeling parameter appears as a new column for each site namedOffload to Intel Xeon Phi. If selected, theScalability of Maximum Site Gaingraph displaysCoprocessor Threadson the X axis. If unselected, the graph displaysCPU Counton the X axis.
- In the upper-right corner, an additional modeling parameter appears. That is, both the total number ofCoprocessor Threadsand theCPU Countappear because both the number of CPUs and the coprocessor's total number of hardware threads should be considered to predict parallel execution.
- Additional modeling parameters appear belowRuntime Modelingarea underIntel Xeon Phi Advanced Modeling- seeIntel® Xeon Phi™Advanced Modeling.
- When the column namedOffload to Intel Xeon Phiis selected, the graph's appearance changes to a gray-green color and the X axis displaysCoprocessor Threadsinstead ofCPU Count. This graph shows the predicted performance of the manycore parallel coprocessor and its host CPUs. For many applications, the number of task instances does not scale enough to fully utilize the many cores of the parallel coprocessor, as indicated by a hover tip. Applications that are not appropriate for anIntel Xeon Phiprocessing system have values that appear in the gray part of the graph; in this case, try modeling other types of theTarget System. Applications that are appropriate for offload to anIntel Xeon Phiprocessing system have values that appear in the green part of the graph.The lines between the graph's gray and green areas is a reference baseline, where the reference CPU chosen to calculate theIntel Xeonprocessor peak baseline is a dual-socket 8-coreIntel Xeonprocessor E5-26xx product family (2.7 GHz, 16 cores total). When theMaximum Site Gainexceeds this baseline, you might consider using anIntel Xeon Phicoprocessor rather than anIntel Xeonor similar processor.
Site Details Tab
If you chose a
Target System
of
CPU
, after you click the
Site Details
tab (next to
Site Performance Scalability
), the lower part of the Suitability Report shows details about the selected site, as well as details about each task and lock within that site.
