5.5.2 Heat Map mode

Heat Map mode in the Timeline view shows you a list of processes and threads 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 5-20 Heat Map mode
Heat Map mode

Here is what each of the colored bins in the Heat Map represent:
White or black, depending on the theme
The process is not running.
Light gray or dark gray, depending on the theme
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 a percentage of total instructions during this bin. Red indicates a higher percentage.


The [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 is gray.
Blue dashes
CPU contention caused a delay. This can happen if there are too many processes and not enough cores to handle them.
Red dashes
An I/O operation caused a delay. The process stopped while a read or a write to disk occurred.
If you select one or more processes or threads, the filterable chart series in the Timeline view update to show only activity caused by the selected processes and threads. Other chart series remain unchanged.
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.
Below the Heat Map are two filter fields. Add a regex to the row filter to filter the list of processes and threads. Add a regex to the annotation filter to filter the string annotations displayed in the Heat Map.
Figure 5-21 Filtering annotations
Filtering annotations

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