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 <tglozar@redhat.com>
---
 .../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

On Mon, Oct 27, 2025 at 04:34:01PM +0100, Tomas Glozar wrote:
> 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 <tglozar@redhat.com>
> ---
>  .../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

nit: simply document that the section name must start with "tp/", the
part saying about "tp/timerlat_action" seems redudant, IIUC.

> +        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
>