linux-kernel - [PATCH v4 3/5] perf/core: Account dropped samples from BPF

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Message-ID: <20241023000928.957077-4-namhyung@kernel.org>
Date: Tue, 22 Oct 2024 17:09:26 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>
Cc: Kan Liang <kan.liang@...ux.intel.com>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Stephane Eranian <eranian@...gle.com>,
	Ravi Bangoria <ravi.bangoria@....com>,
	Sandipan Das <sandipan.das@....com>,
	Kyle Huey <me@...ehuey.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	Song Liu <song@...nel.org>,
	bpf@...r.kernel.org
Subject: [PATCH v4 3/5] perf/core: Account dropped samples from BPF

Like in the software events, the BPF overflow handler can drop samples
by returning 0.  Let's count the dropped samples here too.

Acked-by: Kyle Huey <me@...ehuey.com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andrii Nakryiko <andrii@...nel.org>
Cc: Song Liu <song@...nel.org>
Cc: bpf@...r.kernel.org
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 kernel/events/core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 5d24597180dec167..b41c17a0bc19f7c2 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -9831,8 +9831,10 @@ static int __perf_event_overflow(struct perf_event *event,
 	ret = __perf_event_account_interrupt(event, throttle);
 
 	if (event->prog && event->prog->type == BPF_PROG_TYPE_PERF_EVENT &&
-	    !bpf_overflow_handler(event, data, regs))
+	    !bpf_overflow_handler(event, data, regs)) {
+		atomic64_inc(&event->dropped_samples);
 		return ret;
+	}
 
 	/*
 	 * XXX event_limit might not quite work as expected on inherited
-- 
2.47.0.105.g07ac214952-goog