linux-kernel - [PATCH 3/4] rtla/timerlat: Add example for BPF action program

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Message-ID: <20251017144650.663238-4-tglozar@redhat.com>
Date: Fri, 17 Oct 2025 16:46:49 +0200
From: Tomas Glozar <tglozar@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>
Cc: LKML <linux-kernel@...r.kernel.org>,
	Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>,
	John Kacur <jkacur@...hat.com>,
	Luis Goncalves <lgoncalv@...hat.com>,
	Costa Shulyupin <costa.shul@...hat.com>,
	Crystal Wood <crwood@...hat.com>,
	Wander Lairson Costa <wander@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Tomas Glozar <tglozar@...hat.com>
Subject: [PATCH 3/4] rtla/timerlat: Add example for BPF action program

Add an example BPF action program that prints the measured latency to
the tracefs buffer via bpf_printk().

Signed-off-by: Tomas Glozar <tglozar@...hat.com>
---
 tools/tracing/rtla/sample/timerlat_bpf_action.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 tools/tracing/rtla/sample/timerlat_bpf_action.c

diff --git a/tools/tracing/rtla/sample/timerlat_bpf_action.c b/tools/tracing/rtla/sample/timerlat_bpf_action.c
new file mode 100644
index 000000000000..ac1be049a848
--- /dev/null
+++ b/tools/tracing/rtla/sample/timerlat_bpf_action.c
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_tracing.h>
+
+char LICENSE[] SEC("license") = "GPL";
+
+struct trace_event_raw_timerlat_sample {
+	unsigned long long timer_latency;
+} __attribute__((preserve_access_index));
+
+SEC("tp/timerlat_action")
+int action_handler(struct trace_event_raw_timerlat_sample *tp_args)
+{
+	bpf_printk("Latency: %lld\n", tp_args->timer_latency);
+	return 0;
+}
-- 
2.51.0