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-rw-r--r--tools/lib/perf/Documentation/examples/sampling.c119
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 000000000..8e1a926a9
--- /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;
+}