linux-kernel - Re: [PATCH 4/4] Documentation/rtla: Include BPF sample collection

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Message-ID: <Z9A1oN_XdMguNgHy@uudg.org>
Date: Tue, 11 Mar 2025 10:07:44 -0300
From: "Luis Claudio R. Goncalves" <lgoncalv@...hat.com>
To: Tomas Glozar <tglozar@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>, Jonathan Corbet <corbet@....net>,
	linux-trace-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, John Kacur <jkacur@...hat.com>
Subject: Re: [PATCH 4/4] Documentation/rtla: Include BPF sample collection

On Tue, Mar 11, 2025 at 12:49:36PM +0100, Tomas Glozar wrote:
> Add dependencies needed to build rtla with BPF sample collection support
> to README, and document both ways of sample collection in the manpages.
> 
> Signed-off-by: Tomas Glozar <tglozar@...hat.com>
> ---
>  Documentation/tools/rtla/common_timerlat_description.rst | 8 ++++++++
>  tools/tracing/rtla/README.txt                            | 7 +++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/Documentation/tools/rtla/common_timerlat_description.rst b/Documentation/tools/rtla/common_timerlat_description.rst
> index 8cd3e717baa8..49fcae3ffdec 100644
> --- a/Documentation/tools/rtla/common_timerlat_description.rst
> +++ b/Documentation/tools/rtla/common_timerlat_description.rst
> @@ -8,3 +8,11 @@ The *timerlat* tracer outputs information in two ways. It periodically
>  prints the timer latency at the timer *IRQ* handler and the *Thread*
>  handler. It also enables the trace of the most relevant information via
>  **osnoise:** tracepoints.
> +
> +The **rtla timerlat** tool sets the options of the *timerlat* tracer
> +and collects and displays a summary of the results. By default,
> +the collection is done synchronously in kernel space using a dedicated
> +BPF program attached to the *timerlat* tracer. If either BPF or
> +the **osnoise:timerlat_sample** tracepoint it attaches to is

In the last phrase, s/is/are/. So that "If either... or... are unavailable".

Luis

> +unavailable, the **rtla timerlat** tool falls back to using tracefs to
> +process the data asynchronously in user space.
> diff --git a/tools/tracing/rtla/README.txt b/tools/tracing/rtla/README.txt
> index dd5621038c55..43e98311d10f 100644
> --- a/tools/tracing/rtla/README.txt
> +++ b/tools/tracing/rtla/README.txt
> @@ -13,6 +13,13 @@ RTLA depends on the following libraries and tools:
>   - libtraceevent
>   - libcpupower (optional, for --deepest-idle-state)
>  
> +For BPF sample collection support, the following extra dependencies are
> +required:
> +
> + - libbpf 1.0.0 or later
> + - bpftool with skeleton support
> + - clang with BPF CO-RE support
> +
>  It also depends on python3-docutils to compile man pages.
>  
>  For development, we suggest the following steps for compiling rtla:
> -- 
> 2.48.1
> 
---end quoted text---