Review metric measurements
You can review the contents of a history file in a tool window. When you request a tool to display a history file, the onperf utility starts a playback process that reads the data from disk and sends the data to the tool for display.
The playback process is similar to the data-collector process mentioned
under Save metric values to a file. However,
instead of reading data from shared memory, the playback process reads
measurements from a history file. Flow
of data from a history file to an onperf tool window shows the playback process.