linux/tools/lib/perf/Documentation/examples/sampling.c

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#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;
}