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Using VTrace to investigate Windows performance problems

What is VTrace and how do I use it?

Q: What is VTrace?

VTrace is a tool for recording detailed performance information about Windows computers and it is designed to allow diagnosing of performance problems in Valve products. It records ETW (Event Tracing for Windows) traces which contain detailed information about your computer and often let us identify the problem.

Before trying VTrace you should check the suggestions in our Troubleshooting Performance series to see if there may be hardware or software problems that could be harming problems on your machine. It is not uncommon for hardware problems to affect just a few games, due to differences in their architecture.

 

Q: Does VTrace only run on Windows?

Yes.

 

Q: Does VTrace run on Windows XP?

No. VTrace utlilizes ETW, which is only available in Windows Vista and above.

 

Q: How do I install VTrace?

  1. You will need a CD key to add the VTrace software to your Steam account. If you are working directly with a Valve employee on a problem, they should be able to give you one. If not, file a support ticket and describe the performance problems you are seeing, and ask for a CD key.
  2. Activate this CD Key to your Steam account. See our Activating a product on Steam article for more information.
  3. VTrace will now appear in the software section of your library. If you are having trouble locating it, try opening your library, clicking on the blue text next to the Search box, and selecting All Software.

 

Q: How do I capture a trace?

  1. Launch the VTrace application from within Steam. This starts recording.
  2. Run the game, and reproduce the performance problem.
  3. Switch over to VTrace and click "save trace buffers". (Note: the Win+A hotkey doesn't work on Windows 10.) This will save the most recent twenty to thirty seconds to disk. You will hear sounds which indicate when VTrace starts saving the trace and when it finishes. Important: Save the trace relatively quickly after the performance problem happens, ideally within a few seconds. This makes it easier for us, when looking at the trace, to locate the problematic time period.
  4. It might take a few seconds for VTrace to save the trace file to disk. During this time VTrace will be unresponsive.

 

Q: How do I submit a trace?

  1. Bring the VTrace application to the foreground.
  2. Select the trace you want to submit.
  3. Click "Upload trace to Valve".
  4. Enter a description of the problem. Make sure your description includes ALL of the following:
    • Steam username
    • Email address
    • If you got in contact with a Valve employee through some other forum or service (like reddit), include your username on that service, so we know who you are!
    • A detailed description of what you are seeing. What actions did you take, and what problem did you experience?
    • Approximately how many seconds elapsed between the problem you experienced, and the time you saved the trace.
    • The name of the Valve employee you are working with on this problem, if any.
    • Support ticket number, if you have one.
    ** A trace without this information is useless and will not be examined. Please don't waste your time by submitting a trace without it! **
  5. Click on OK to finish.
     
  6. The trace is encrypted and uploaded to Valve securely.

 

Q: Is any personal information captured?

Because ETW is a system-wide profiler it records information about all activity on your machine, not just Valve games. It records details about your hardware, programs running on your computer, and files and registry keys accessed. VTrace does not record the contents of files on your computer, just the paths of files accessed while tracing is enabled. Within Valve games it also records user input, and if "Record Input" is checked it records user input in all programs. Tracing will only be enabled when VTrace is running. VTrace only records traces - it does not automatically send them to Valve. You can choose to send the recorded traces to Valve, if you are working with Valve on a customer support issue. Valve will use the traces you send to assist with your customer support issue, and will protect the information in accordance with Valve's privacy policy.

 

Q: What if I don't have a Steam client on that computer?

if you don't have a Steam client on the computer with the performance issues (for example, a dedicated gameserver), just install VTrace using a Steam client, and then copy the tool to the other computer. You will need to manually run either WPTx86-x86_en-us.msi (for 32-bit Windows) or WPTx64-x86_en-us.msi (for 64-bit Windows) from the VTrace directory in order to install some support files, and then run VTrace.exe.
 

 

Q: What is a "lag spike"?

Your guess is as good as ours. This term (and others like it) are often used to describe basically any disruption in smooth gameplay, although the underlying problems are quite diverse. You can help by describing as specifically as possible what you are observing. Here are the sorts of questions your description of the problem should clarify:
 

  • Can you tell if the client-side frame rate is smooth or slow? Is the screen repainting quickly, but some objects are just not moving? If the HUD, particle effects, or other cosmetic effects continue to animate while “gameplay” objects such as characters and projectiles move in an erratic fashion, then your client frame is still smooth.
  • Do objects have continuous motion, or do they stand still on the screen for large periods of time? If so, is it all objects, or just certain objects?
  • Do objects move forward and then warp back? ("Some people refer to this behaviour as "rubber banding".)
  • Does the audio stutter?
  • Are all of the game objects moving in an odd way, or just your own character?
  • If you have any network, frame rate, CPU monitoring data, exactly which of those metrics spike?

 

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