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Windows Xperf diskio action does not show me a file that a program reads during the performance trace session

I run xperf in order to get trace info for a program when I run it. The program reads a file. It is a .NET program written in F#, the file is read here:

System.IO.File.ReadAllLines("MyReadFile.txt")

Well. I run xperf:

xperf -on DiagEasy

I stop xperf and merge in a file:

xperf -d myfile.etl

OK.

Now I write:

xperf -i myfile.etl -o myfile_stat.txt -a diskio -detail

I do this so I can get a file with all info about files. The file shown is a text file formatted in order to let me see disk statistics by file. Each file which has been manipulated during the trace session is shown with much data regarding the process which read/wrote the file and so on...

But MyReadFile.txt does not appear there.

Why????? Is it because the cpu sampling frequency is too low? How can I change it?...

However, my program reads the file, I'm sure, the program starts and prints out the content...

Thanks

Solution

  • File I/O monitoring isn't based on sampling. Instead the relevant ETW provider raises events for each monitored I/O. It shouldn't miss anything.

    If this were my code I'd suspect it hadn't really read the file. ERROR_FILE_NOT_FOUND, perhaps?

    Also, that flag should be DiagEasy, not EasyDiag.

    FWIW, here's how I do file monitoring, with stack traces enabled:

    xperf -on PROC_THREAD+LOADER+FILE_IO+FILE_IO_INIT+FILENAME -stackwalk FileCreate+FileRead+FileWrite+FileFlush+FileQueryInformation+FileSetinformation+FileDelete

    Regards, Gary