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Procedure: How to Use Profiles to Capture Traces

  • Artigo

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.