Intel Software Network articles Feed

"Attach debugger?" Message

Sun, 21 Nov 2010 21:00:00 -0800

Problem :
After running an VTune™ Amplifier XE 2011 data analysis from within Microsoft* Visual Studio*, you may see a dialog box with the caption "Attach debugger?" and the message

No module name pythonhelpers1 (1):

Pressing Yes or No usually results in the display of the collected data. Sometimes the dialog is NOT displayed and in those cases the data may not be displayed.

Environment :
Microsoft* Windows*

Root Cause :
There is a compatibility issue with the current releases of Intel® Parallel Amplifier 2011 and VTune Amplifier XE. Both tools use different versions of a DLL and the version used by Parallel Amplifier is not compatible with VTune Amplifier XE. If that version is loaded by Visual Studio, VTune Amplifier XE cannot load the newer version of the DLL, which is required for correct operation.

Resolution :
Until a fix is available, closing down Visual Studio*, restarting it, and using VTune Amplifier XE prior to any other activity should resolve the issue for the duration of the Visual Studio invocation. The problem arises when Parallel Amplifier functionality is used prior to VTune Amplifier XE in the same Visual Studio session.

Intel® Parallel Amplifier Under the Hood

Wed, 01 Sep 2010 21:00:00 -0700

Intel® Parallel Amplifier’s three analysis types are designed to each give you insight into different aspects of your program’s performance. Each level of analysis collects additional information. Here’s how it works.

Hotspots

The first type of analysis, Hotspots, is the most lightweight. Running it only takes about as much time as it takes to run your application normally (outside of Intel® Parallel Amplifier). While your app executes, Intel Parallel Amplifier’s data collector will periodically take samples. For each sample, the collector cooperates with the operating system to interrupt your program and gather data. It records the instruction pointer (IP) for each CPU core that is executing your app, as well as the call stack (saved as part of the O/S’s data structures). Once your application finishes executing, Intel Parallel Amplifier takes all of the IP samples and uses them to figure out how long each function was executing, and it uses all of the call stack samples to create a Call Tree for the whole program. In order to create the hotspots list and the call tree, Intel Parallel Amplifier also uses information about your program’s data and instruction space stored in its program debug database (.pdb file).

Concurrency

The second type of analysis, Concurrency, works in the same way but collects a bit more information. It also records data on the status of each of the application’s threads – running, ready to run, and blocked. Once all the samples have been collected, Intel Parallel Amplifier analyzes the data to determine the percentage of time your application’s threads were active. This is called the Concurrency Level, and it is broken down per function. Ideally, the concurrency level for your app should match the number of processors on the system – this is what Intel Parallel Amplifier calls Fully Utilized.

Locks and Waits

The last type of analysis is called Locks and Waits, and it is the most processor intensive. Your application may take longer to run under Locks and Waits analysis, and here’s why. In addition to collecting the data above, Intel Parallel Amplifier will add instructions to your compiled program. These instructions are placed wherever your program uses threading and synchronization API calls, and their purpose is to measure the wait times elapsed whenever a thread is not active. This timing information is combined with symbol information found in the .pdb file to create a picture of where your application is waiting, and what it is waiting on. Locks and other structures which might cause threads to wait are called Synchronization Objects. After running this analysis Intel Parallel Amplifier will show you a list of these objects along with the wait time for each and the concurrency of your app during the wait.

How to use Intel(R) Parallel Amplifier with application compiled with symbols but source files are not available

Wed, 01 Sep 2010 21:00:00 -0700

Some users have an EXE file and related DLL files (with corresponding PDB files), but have no sources for EXE or DLLs. Can they use Intel(R) Parallel Amplifier in this situation?

Yes! The Intel(R) Parallel Amplifier is supported on Microsoft* Visual Studio* 2005/2008 - the user should create .sln file, .vcproject file in Solution Explorer.

1. Use wizard to create a new project for existing code

2. Specify project file location and project file name (it could be same as your EXE file)

3. Add existing item (EXE file) to current project

4. Manually create "Debug" folder under project file location.

5. Manually copy all EXE/DLL files and PDB files to the "Debug" folder

6. Ensure that you can run "Debug\Start Without Debugging" in Microsoft* Visual Studio*, then you can run Intel(R)Parallel Amplifier.

How to analyze a portion of your application

Thu, 12 Mar 2009 21:00:00 -0700

Sometimes, you only want to profile a portion of your application's run time. For example, you may not want to profile the startup phase or the shutdown phase. This article will describe how to use the Intel® Parallel Amplifer in such a situation.

As an example, we will demonstrate using the matrix example included with the Parallel Amplifier. Let's assume we only want to profile algorithm_3() for Concurrency and not algorithm_1() or algorithm_2(). We know from the program's structure that these three routines are called sequentially, algorithm_1(), then algorithm_2(), then algorithm_3(). This is similar to an application where we don't care about the startup phase and only want to analyze the main purpose of the application, e.g., algorithm_3().

When the example was run on a dual core system, the following results were obtained:

Based on the timing information, approximately 2 seconds is consumed by algorithm_1() and algorithm_2(), when added together (e.g., 0.58+1.55 seconds).

The Parallel Amplifier provides a configuration setting that allows you to delay data collection. Access this setting in one of two ways:

From the Project menu, select Intel Parallel Amplifier Project properties (see Figure A), or
Right-click on the project in the Solution Explorer and select Intel Parallel Amplifier, and then Project Properties (see Figure B)

Then, under Collection, check the Start data collection paused and Resume collection after, sec., as below.

Now, if we run the Amplifer on our application, we see results similar to the following:

We still captured some time in algorithm_2() - almost a full second. Obviously, the next step is to increase the resume time to 3 seconds and re-run the analysis. The results follow:

Alternately, use the GUI to pause or resume data collection at any time after the application is launched. You can control when data is collected using this method, at a coarse granularity.

Either check or uncheck the Start data collection paused option, depending on if you want to collect data at the start of your application or not. Then, during execution of the application, press the Continue button to resume data collection...

And the Pause button to pause data collection.

How to analyze an application without having a Visual Studio* project

Sat, 28 Feb 2009 21:00:00 -0800

Intel® Parallel Amplifier and Intel® Parallel Inspector are fully integrated applications within Microsoft Visual Studio* and so require a Visual Studio project to store the configuration needed for testing. So how do you use the Amplifier or Inspector on an application for which you only have the binary files?

There are two ways to create an Amplifier or Inspector analysis project when all you have is the .exe and associated .dlls. The first uses a command prompt window. Within the command prompt window, type a command similar to the following:

devenv /debugexe MyApplication.exe --app-param1 value1 --app-switch1

This command will start the Visual Studio IDE, create a project for MyApplication.exe application and set the application's options. Next, right-click the project in the Visual Studio Solution Explorer or find the tool bar and start Amplifier or Inspector as usual. The results will be stored in My Amplifier or Inspector Results directory, which is created near the executable. You can override where the results are stored in preferences and target them to a specific directory.

The second method utilizes the Visual Studio environment. Start Visual Studio and create a solution based on a single executable file: File -> Open -> Project/Solution.

Select your .exe file. A solution with the same name as the .exe file is created. Save the solution, then right-click the project in the Visual Studio Solution Explorer or find the tool bar and start Amplifier or Inspector as usual.