How to: Attach the profiler to a native stand-alone application and collect application statistics by using the command line

Applies to: Visual Studio Visual Studio for Mac

This article describes how to use the Visual Studio Profiling Tools command-line tools to attach the profiler to a running native stand-alone (client) application and collect performance statistics by using the sampling method.

When the profiler is attached to the application, you can pause and resume data collection. To end a profiling session, the profiler must no longer be attached to the application and the profiler must be explicitly shut down.

Attach the profiler

To attach the profiler to a target application by using the profiler, you use the VSPerfCmd/start and /attach options to initialize the profiler and attach to the target application. You can specify /start and /attach and their respective options on a single command line. You can also add the /globaloff option to pause data collection at the start of the target application. You then use /globalon to start to collect data.

To attach the profiler to a running .NET Framework application

1. Open a Command Prompt window.

2. Start the profiler. Type:

   VSPerfCmd /start:sample /output: OutputFile [Options]

   • The/start:sample option initializes the profiler.

   • The /output:OutputFile option is required with /start. OutputFile specifies the name and location of the profiling data (.vsp) file.

     You can use any of the following options with the /start:sample option.

   Option	Description
   /user :[Domain\]UserName	Specifies the domain and user name of the account that owns the profiled process. This option is required only if the process is running as a user other than the logged-on user. The process owner is listed in the User Name column on the Processes tab of Windows Task Manager.
   /crosssession	Enables profiling of processes in other sessions. This option is required if the ASP.NET application is running in a different session. The session idenitifier is listed in the Session ID column on the Processes tab of Windows Task Manager. /CS can be specified as an abbreviation for /crosssession.
   /wincounter : WinCounterPath	Specifies a Windows performance counter to be collected during profiling.
   /automark : Interval	Use with /wincounter only. Specifies the number of milliseconds between Windows performance counter collection events. Default is 500 ms.
   /events : Config	Specifies an Event Tracing for Windows (ETW) event to be collected during profiling. ETW events are collected in a separate (.etl) file.

3. Attach the profiler to the target application. Type:

   VSPerfCmd /attach :{PID|ProcName} [Sample Event]

   PID specifies the process ID of the target application. ProcessName specifies the name of the process. Note that if you specify ProcessName and multiple processes that have the same name are running, results are unpredictable. You can view the process IDs of all running processes in Windows Task Manager.

   By default, performance data is sampled every 10,000,000 non-halted processor clock cycles. This is approximately 100 times every second on a 1GH processor. You can specify one of the following options to change the clock cycle interval, or to specify a different sampling event.

   Sample event	Description
   /timer : Interval	Changes the sampling interval to the number of non-halted clock cycles that are specified by Interval.
   /pf[:Interval]	Changes the sampling event to page faults. If Interval is specified, sets the number of page faults between samples. Default is 10.
   /sys [:Interval]	Changes the sampling event to system calls from the process to the operating system kernel (syscalls). If Interval is specified, sets the number of calls between samples. Default is 10.
   /counter : Config	Changes the sampling event and interval to the processor performance counter and the interval that is specified in Config.

Control data collection

When the target application is running, you can use VSPerfCmd.exe options to start and stop the writing of data to the profiler data file. Controlling data collection enables you to collect data for a specific part of program execution, such as the starting or shutdown of the application.

To start and stop data collection

• The following pairs of VSPerfCmd options start and stop data collection. Specify each option on a separate command line. You can turn data collection on and off multiple times.

  Option	Description
  /globalon /globaloff	Starts (/globalon) or stops (/globaloff) data collection for all processes.
  /processon : PID /processoff : PID	Starts (/processon) or stops (/processoff) data collection for the process that is specified by PID.
  /attach : PID /detach	/attach starts to collect data for the process specified by PID. /detach stops data collection for all processes.

End the profiling session

To end a profiling session, the profiler must be detached from all profiled processes and the profiler must be explicitly shut down. You can detach the profiler from an application that was profiled by using the sampling method by closing the application or by calling the VSPerfCmd /detach option. You then call the VSPerfCmd /shutdown option to turn the profiler off and close the profiling data file. The VSPerfClrEnv /off command clears the profiling environment variables.

To end a profiling session

1. Perform one of the following steps to detach the profiler from the target application.

   • Type VSPerfCmd /detach

     -or-

   • Close the target application.

2. Shut down the profiler. Type:

   VSPerfCmd /shutdown

3. (Optional) Clear the profiling environment variables. Type:

   VSPerfClrEnv /off

See also

• Profile stand-alone applications
• Sampling method data views