| # Atrace categories |
| |
| The atrace command (and the perfetto configuration) allow listing **categories** |
| to select subsets of events to be traced. |
| |
| Each category can include some userspace events and some ftrace events. |
| |
| ## Vendor categories |
| |
| It's possible to extend exiting categories (or to define new categories) from |
| the /vendor partition in order to add hardware specific ftrace events. |
| |
| Since android 14, if the file `/vendor/etc/atrace/atrace_categories.txt`, atrace |
| and perfetto will consider the categories and ftrace events listed there. |
| |
| The file contains a list of categories, and for each category (on the following |
| lines, indented with one or more spaces of time), a list of ftrace events that |
| should be enabled when the category is enabled. |
| |
| Each ftrace event should be a subdirectory in `/sys/kernel/tracing/events/` and |
| should be of the form `group/event`. Listing a whole group is not supported, |
| each event needs to be listed explicitly. |
| |
| It is not an error if an ftrace event is listed in the file, but not present on |
| the tracing file system. |
| |
| Example: |
| |
| ``` |
| gfx |
| mali/gpu_power_state |
| mali/mali_pm_status |
| thermal_tj |
| thermal_exynos/thermal_cpu_pressure |
| thermal_exynos/thermal_exynos_arm_update |
| ``` |
| |
| The file lists two categories (`gfx` and `thermal_tj`). When the `gfx` category |
| is enabled, atrace (or perfetto) will enable |
| `/sys/kernel/tracing/events/mali/gpu_power_state` and |
| `/sys/kernel/tracing/events/mali/mali_pm_status`. When the `thermal_tj` category |
| is enabled, atrace (or perfetto) will enable |
| `/sys/kernel/tracing/events/thermal_exynos/thermal_cpu_pressure` and |
| `/sys/kernel/tracing/events/thermal_exynos/thermal_exynos_arm_update`. |
| |
| Since android 14, if the file `/vendor/etc/atrace/atrace_categories.txt` exists |
| on the file system, perfetto and atrace do not query the android.hardware.atrace |
| HAL (which is deprecated). |
