Many chart series in the Timeline view can be filtered, based on the threads or processes that are selected in the Heat Map, Core Map, Cluster Map, or in the process list in Processes mode.
When there is an active selection, the affected chart series only show activity resulting from the selected processes or threads. The charts rescale to the limit of the filtered data. The letter F next to the series name indicates that the series is filtered.
Like the CPU Activity chart, the GPU Vertex and Fragment charts display only activity that the selected processes or threads initiate. You can then differentiate between GPU activity that your application causes and activity resulting from other applications or system services.