1 files changed, 119 insertions, 0 deletions
diff --git a/tools/lib/perf/Documentation/examples/sampling.c b/tools/lib/perf/Documentation/examples/sampling.c
new file mode 100644
index 000000000000..8e1a926a9cfe
--- /dev/null
+++ b/tools/lib/perf/Documentation/examples/sampling.c
@@ -0,0 +1,119 @@
+#include <linux/perf_event.h>
+#include <perf/evlist.h>
+#include <perf/evsel.h>
+#include <perf/cpumap.h>
+#include <perf/threadmap.h>
+#include <perf/mmap.h>
+#include <perf/core.h>
+#include <perf/event.h>
+#include <stdio.h>
+#include <unistd.h>
+
+static int libperf_print(enum libperf_print_level level,
+                         const char *fmt, va_list ap)
+{
+	return vfprintf(stderr, fmt, ap);
+}
+
+union u64_swap {
+	__u64 val64;
+	__u32 val32[2];
+};
+
+int main(int argc, char **argv)
+{
+	struct perf_evlist *evlist;
+	struct perf_evsel *evsel;
+	struct perf_mmap *map;
+	struct perf_cpu_map *cpus;
+	struct perf_event_attr attr = {
+		.type        = PERF_TYPE_HARDWARE,
+		.config      = PERF_COUNT_HW_CPU_CYCLES,
+		.disabled    = 1,
+		.freq        = 1,
+		.sample_freq = 10,
+		.sample_type = PERF_SAMPLE_IP|PERF_SAMPLE_TID|PERF_SAMPLE_CPU|PERF_SAMPLE_PERIOD,
+	};
+	int err = -1;
+	union perf_event *event;
+
+	libperf_init(libperf_print);
+
+	cpus = perf_cpu_map__new(NULL);
+	if (!cpus) {
+		fprintf(stderr, "failed to create cpus\n");
+		return -1;
+	}
+
+	evlist = perf_evlist__new();
+	if (!evlist) {
+		fprintf(stderr, "failed to create evlist\n");
+		goto out_cpus;
+	}
+
+	evsel = perf_evsel__new(&attr);
+	if (!evsel) {
+		fprintf(stderr, "failed to create cycles\n");
+		goto out_cpus;
+	}
+
+	perf_evlist__add(evlist, evsel);
+
+	perf_evlist__set_maps(evlist, cpus, NULL);
+
+	err = perf_evlist__open(evlist);
+	if (err) {
+		fprintf(stderr, "failed to open evlist\n");
+		goto out_evlist;
+	}
+
+	err = perf_evlist__mmap(evlist, 4);
+	if (err) {
+		fprintf(stderr, "failed to mmap evlist\n");
+		goto out_evlist;
+	}
+
+	perf_evlist__enable(evlist);
+	sleep(3);
+	perf_evlist__disable(evlist);
+
+	perf_evlist__for_each_mmap(evlist, map, false) {
+		if (perf_mmap__read_init(map) < 0)
+			continue;
+
+		while ((event = perf_mmap__read_event(map)) != NULL) {
+			int cpu, pid, tid;
+			__u64 ip, period, *array;
+			union u64_swap u;
+
+			array = event->sample.array;
+
+			ip = *array;
+			array++;
+
+			u.val64 = *array;
+			pid = u.val32[0];
+			tid = u.val32[1];
+			array++;
+
+			u.val64 = *array;
+			cpu = u.val32[0];
+			array++;
+
+			period = *array;
+
+			fprintf(stdout, "cpu %3d, pid %6d, tid %6d, ip %20llx, period %20llu\n",
+				cpu, pid, tid, ip, period);
+
+			perf_mmap__consume(map);
+		}
+
+		perf_mmap__read_done(map);
+	}
+
+out_evlist:
+	perf_evlist__delete(evlist);
+out_cpus:
+	perf_cpu_map__put(cpus);
+	return err;
+}