More detailed info on DPCs and ISRs (trouble shooting latency issues)


Cadal

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Hi Guys,

 

Been working to resolve some usb sound issues even though im using controller passthrough.

Came across this link from mbk1969 on 'The guru of 3D' - https://forums.guru3d.com/threads/simple-way-to-trace-dpcs-and-isrs.423884/ that provides more detail then Latencymon.

 

Quote

Everyone uses Latencymon nowadays to troubleshoot DPC latencies. I stumbled across even simpler way provided by Microsoft.

1. Install "Windows Performance Toolkit" from Windows ADK (for your version of Windows)
https://docs.microsoft.com/en-us/windows-hardware/get-started/adk-install
For my Win10 1803 it costs

2. Launch elevated command prompt and execute to start the trace:

Code:

cd "C:\Program Files (x86)\Windows Kits\10\Windows Performance Toolkit" xperf -on base+interrupt+dpc

 

3. Run the game, the video, or whatever you are trying to troubleshoot.

4. Return to command prompt to stop the trace and to save the trace file:

Code:

xperf -d c:\temp\trace.etl

 

Choose your own path and name for that trace file.

5. Generate the text report file for DPCs and ISRs:

Code:

xperf -i c:\temp\trace.etl -o c:\temp\report.txt -a dpcisr

6. Now you can open that text report file to browse quite detailed info.


-where "us", "usec" and "usecs" stand for "microseconds".
-You can see how many DPCs/ISRs for each module fall to ranges - between 0 and 1 microseconds, between 1 and 2 microseconds, and so forth.
-Also you can see summaries for DPCs and ISRs per CPU.

Feel free to go thank him direct. Just posting here in case the other post goes a missing.

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