linux-kernel - [PATCH v7 01/10] perf record --off-cpu: Add --off-cpu-thresh option

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Message-ID: <20241108204137.2444151-2-howardchu95@gmail.com>
Date: Fri,  8 Nov 2024 12:41:28 -0800
From: Howard Chu <howardchu95@...il.com>
To: acme@...nel.org,
	peterz@...radead.org
Cc: namhyung@...nel.org,
	irogers@...gle.com,
	mingo@...hat.com,
	mark.rutland@....com,
	james.clark@...aro.org,
	alexander.shishkin@...ux.intel.com,
	jolsa@...nel.org,
	adrian.hunter@...el.com,
	kan.liang@...ux.intel.com,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Howard Chu <howardchu95@...il.com>
Subject: [PATCH v7 01/10] perf record --off-cpu: Add --off-cpu-thresh option

Specify the threshold for dumping offcpu samples with --off-cpu-thresh,
the unit is us (microsecond). Default value is 500000us (500ms, 0.5s).

Suggested-by: Ian Rogers <irogers@...gle.com>
Signed-off-by: Howard Chu <howardchu95@...il.com>
---
 tools/perf/builtin-record.c | 26 ++++++++++++++++++++++++++
 tools/perf/util/off_cpu.h   |  1 +
 tools/perf/util/record.h    |  1 +
 3 files changed, 28 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f83252472921..ee04fdd7f2ca 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3149,6 +3149,28 @@ static int record__parse_mmap_pages(const struct option *opt,
 	return ret;
 }
 
+static int record__parse_off_cpu_thresh(const struct option *opt,
+					const char *str,
+					int unset __maybe_unused)
+{
+	struct record_opts *opts = opt->value;
+	char *endptr;
+	u64 off_cpu_thresh;
+
+	if (!str)
+		return -EINVAL;
+
+	off_cpu_thresh = strtoull(str, &endptr, 10);
+
+	/* threshold isn't string "0", yet strtoull() returns 0, parsing failed */
+	if (*endptr || (off_cpu_thresh == 0 && strcmp(str, "0")))
+		return -EINVAL;
+	else
+		opts->off_cpu_thresh = off_cpu_thresh;
+
+	return 0;
+}
+
 void __weak arch__add_leaf_frame_record_opts(struct record_opts *opts __maybe_unused)
 {
 }
@@ -3342,6 +3364,7 @@ static struct record record = {
 		.ctl_fd              = -1,
 		.ctl_fd_ack          = -1,
 		.synth               = PERF_SYNTH_ALL,
+		.off_cpu_thresh      = OFFCPU_THRESH,
 	},
 };
 
@@ -3564,6 +3587,9 @@ static struct option __record_options[] = {
 	OPT_BOOLEAN(0, "off-cpu", &record.off_cpu, "Enable off-cpu analysis"),
 	OPT_STRING(0, "setup-filter", &record.filter_action, "pin|unpin",
 		   "BPF filter action"),
+	OPT_CALLBACK(0, "off-cpu-thresh", &record.opts, "us",
+		     "Dump off-cpu samples if off-cpu time reaches this threshold. The unit is microsecond (default: 500000)",
+		     record__parse_off_cpu_thresh),
 	OPT_END()
 };
 
diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
index 2dd67c60f211..c6edc0f7c40d 100644
--- a/tools/perf/util/off_cpu.h
+++ b/tools/perf/util/off_cpu.h
@@ -16,6 +16,7 @@ struct record_opts;
 			      PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
 			      PERF_SAMPLE_CGROUP)
 
+#define OFFCPU_THRESH 500000ull
 
 #ifdef HAVE_BPF_SKEL
 int off_cpu_prepare(struct evlist *evlist, struct target *target,
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index a6566134e09e..3c11416e6627 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -79,6 +79,7 @@ struct record_opts {
 	int	      synth;
 	int	      threads_spec;
 	const char    *threads_user_spec;
+	u64	      off_cpu_thresh;
 };
 
 extern const char * const *record_usage;
-- 
2.43.0