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Procedure: How to Use Profiles to Capture Traces

The following procedure shows you how to capture traces by using profiles. If you are doing memory analysis, you might want to write your trace to a file since ETW writes through and doesn't disturb the cache. If you are doing a disk I/O analysis, you might want to save your trace into a circular buffer in memory. There are also other considerations such as whether you need to capture a long trace, which wouldn't fit into a buffer in memory, or if you only care about the last 5-10 seconds of the trace content.

  • Select a profile such as perf!FileIOProfiles.InBuffer and use the following command to display information about it:

    
    xperf -profiles perf!FileIOProfiles.InBuffer
    
    

    The result of this command would be listing all the profiles, as in the previous step, followed by the sessions and providers in that profile, for example:

    Profile: FileIOProfiles.InBuffer

    Sessions: FileIOProfiles.InBuffer.Sessions

    Session: FileIOProfiles.InBuffer.Sessions[0].Kernel[0]

    Session: FileIOProfiles.InBuffer.Sessions[0].User[0]

    Providers: FileIOProfiles.InBuffer.Providers

    Provider: FileIOProfiles.InBuffer.Providers[0].Kernel[0]

    Provider: FileIOProfiles.InBuffer.Providers[0].User[0]

  • Assuming that you chose to use a file-based trace, start an InSequentialFile trace profile by using the following command:

    
    xperf -start perf!GeneralProfiles.InSequentialFile
    
    

    If a problem occurs an error is reported. For example, starting the same profile twice would result in an error that the session is already running.

  • Show which InSequentialFile loggers have already started for a specific profile by using the following command:

    
    xperf -profileloggers perf!GeneralProfiles.InSequentialFile
    
    

    The response to this command would be as shown below.

    Session Status for "perf!GeneralProfiles.InSequentialFile":
    "NT Kernel Logger" : Running
    PerfCoreUserSession_InSequentialFile : Running
    
  • Stop the InSequentialFile trace profile, save the traces, and merge them into a trace file, such as merged.etl. Do that by using the following command:

    
    xperf -stop perf!GeneralProfiles.InSequentialFile merged.etl
    
    

    If a problem occurs an error is reported.

  • Start InSequentialFile trace profile, overriding, at start time, MaxBuffers values for all ETW sessions, for which loggers are to be started to 256. To do that, use the following command:

    
    xperf -start perf!GeneralProfiles.InSequentialFile -MaxBuffers 256
    
    

    If a problem occurs an error is reported.

  • Update MaxBuffers values for the active InSequentialFile ETW loggers specified in the trace profile. To do that, use the following command:

    
    xperf -update perf!GeneralProfiles.InSequentialFile -MaxBuffers 256
    
    

    No response is displayed after issuing this command.

  • You can display the resulting trace by using the following command:

    
    xperfview merged.etl
    
    

    As usual, you can check or uncheck any of the check boxes to hide or show a specific graph. For more information on visualizing traces, see Quick Start.

 

 

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Build date: 5/5/2012

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