Add new option --bpf-action into common_timerlat_options.txt, including the format in which it takes the BPF program, and a reference to an example.
Signed-off-by: Tomas Glozar <[email protected]> --- .../tools/rtla/common_timerlat_options.rst | 20 +++++++++++++++++++ 1 file changed, 20 insertions(+) diff --git a/Documentation/tools/rtla/common_timerlat_options.rst b/Documentation/tools/rtla/common_timerlat_options.rst index c6046fcf52dc..7e08a27e87fe 100644 --- a/Documentation/tools/rtla/common_timerlat_options.rst +++ b/Documentation/tools/rtla/common_timerlat_options.rst @@ -65,3 +65,23 @@ Set timerlat to run without workload, waiting for the user to dispatch a per-cpu task that waits for a new period on the tracing/osnoise/per_cpu/cpu$ID/timerlat_fd. See linux/tools/rtla/example/timerlat_load.py for an example of user-load code. + +**--bpf-action** *bpf-program* + + Loads a BPF program from an ELF file and executes it when a latency threshold is exceeded. + + The BPF program must be a valid ELF file loadable with libbpf. The program must contain + a function named ``action_handler``, declared with ``SEC("tp/timerlat_action")`` or + a different section name beginning with "tp/". This tells libbpf that the program type is + BPF_PROG_TYPE_TRACEPOINT, without it, the program will not be loaded properly. + + The program receives a ``struct trace_event_raw_timerlat_sample`` parameter + containing timerlat sample data. + + An example is provided in ``tools/tracing/rtla/example/timerlat_bpf_action.c``. + This example demonstrates how to create a BPF program that prints latency information using + bpf_trace_printk() when a threshold is exceeded. + + **Note**: BPF actions require BPF support to be available. If BPF is not available + or disabled, the tool will fall back to tracefs mode and BPF actions will not be + supported. -- 2.51.0
