You may run across the situation where you need to import an existing Perfmon (or System Monitor) binary log file into and Excel spreadsheet or SQL database.  The obvious first step is to convert it to CSV format.  It took googling numerous forums to figure out how to do this, so I thought that I’d document it here for future reference.

The relog.exe utility, which ships with the OS, has the ability to convert between Perfom log file formats and merge several log files into one file.  It has some nice filtering capabilities including filtering by time, counters, and nth record.  Example syntax for simply converting between file formats:

relog -f csv inputfile.blg -o outputFile.csv

You can display all the options by simply typing relog -? at the command prompt.