Heat Map mode
The Heat Map shows you a list of processes that were active during the capture session. The entries are derived from process and thread trace data from the Linux kernel scheduler. Weighted colors reflect the number of samples in each process or thread.
Open Heat Map mode using the mode menu in the bottom left of the Timeline view.
Figure 6-9 Process bars in Heat Map mode
Here is what each of the colored bins in the Heat Map represent:
- The process is not running.
- The process has started, but is dormant. It could be sleeping, waiting on user input, or waiting for some other process to finish.
- Yellow to Red
- The process is responsible for some percentage of total instructions during this bin. Red indicates a higher percentage.
NoteThe [idle] process is color-coded differently to the other processes in the Timeline view. When the system is fully idle, it is bright blue. When it is partially idle it is a lighter shade of blue, and when the system is fully active, it appears white.
- Blue Dashes
- CPU contention caused a delay. This can happen if there are too many
processes and not enough cores to handle them.
Figure 6-10 CPU contention dashes in the Timeline view
- Red Dashes
- An I/O operation caused a delay. The process stopped while a read or a write to disk occurred.
If you select any number of processes or threads, all the charts in the Timeline view update to reflect only activity caused by the selected processes and threads. All charts that do not contain the necessary process information are blanked out.
Each of the multi-threaded or annotated processes in the list have a disclosure control. Use the control to show each of the threads and annotations for that process. Annotations shown here can be hierarchical, with annotation groups each containing a set of channels, as defined by the macros inserted in your code.
NoteSelecting a process or thread in the Heat Map affects the CPU Activity, CPU Wait, GPU Vertex, and GPU Fragments charts. All of these charts update to reflect usage based on the current selection in the Heat Map.
If you activate the disclosure control to show threads and annotations for that process, a filter button appears to the right of the process title. Use this to filter threads within that process.
Figure 6-11 Filter button