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

   1#include <linux/perf_event.h>
   2#include <perf/evlist.h>
   3#include <perf/evsel.h>
   4#include <perf/cpumap.h>
   5#include <perf/threadmap.h>
   6#include <perf/mmap.h>
   7#include <perf/core.h>
   8#include <perf/event.h>
   9#include <stdio.h>
  10#include <unistd.h>
  11
  12static int libperf_print(enum libperf_print_level level,
  13                         const char *fmt, va_list ap)
  14{
  15        return vfprintf(stderr, fmt, ap);
  16}
  17
  18union u64_swap {
  19        __u64 val64;
  20        __u32 val32[2];
  21};
  22
  23int main(int argc, char **argv)
  24{
  25        struct perf_evlist *evlist;
  26        struct perf_evsel *evsel;
  27        struct perf_mmap *map;
  28        struct perf_cpu_map *cpus;
  29        struct perf_event_attr attr = {
  30                .type        = PERF_TYPE_HARDWARE,
  31                .config      = PERF_COUNT_HW_CPU_CYCLES,
  32                .disabled    = 1,
  33                .freq        = 1,
  34                .sample_freq = 10,
  35                .sample_type = PERF_SAMPLE_IP|PERF_SAMPLE_TID|PERF_SAMPLE_CPU|PERF_SAMPLE_PERIOD,
  36        };
  37        int err = -1;
  38        union perf_event *event;
  39
  40        libperf_init(libperf_print);
  41
  42        cpus = perf_cpu_map__new(NULL);
  43        if (!cpus) {
  44                fprintf(stderr, "failed to create cpus\n");
  45                return -1;
  46        }
  47
  48        evlist = perf_evlist__new();
  49        if (!evlist) {
  50                fprintf(stderr, "failed to create evlist\n");
  51                goto out_cpus;
  52        }
  53
  54        evsel = perf_evsel__new(&attr);
  55        if (!evsel) {
  56                fprintf(stderr, "failed to create cycles\n");
  57                goto out_cpus;
  58        }
  59
  60        perf_evlist__add(evlist, evsel);
  61
  62        perf_evlist__set_maps(evlist, cpus, NULL);
  63
  64        err = perf_evlist__open(evlist);
  65        if (err) {
  66                fprintf(stderr, "failed to open evlist\n");
  67                goto out_evlist;
  68        }
  69
  70        err = perf_evlist__mmap(evlist, 4);
  71        if (err) {
  72                fprintf(stderr, "failed to mmap evlist\n");
  73                goto out_evlist;
  74        }
  75
  76        perf_evlist__enable(evlist);
  77        sleep(3);
  78        perf_evlist__disable(evlist);
  79
  80        perf_evlist__for_each_mmap(evlist, map, false) {
  81                if (perf_mmap__read_init(map) < 0)
  82                        continue;
  83
  84                while ((event = perf_mmap__read_event(map)) != NULL) {
  85                        int cpu, pid, tid;
  86                        __u64 ip, period, *array;
  87                        union u64_swap u;
  88
  89                        array = event->sample.array;
  90
  91                        ip = *array;
  92                        array++;
  93
  94                        u.val64 = *array;
  95                        pid = u.val32[0];
  96                        tid = u.val32[1];
  97                        array++;
  98
  99                        u.val64 = *array;
 100                        cpu = u.val32[0];
 101                        array++;
 102
 103                        period = *array;
 104
 105                        fprintf(stdout, "cpu %3d, pid %6d, tid %6d, ip %20llx, period %20llu\n",
 106                                cpu, pid, tid, ip, period);
 107
 108                        perf_mmap__consume(map);
 109                }
 110
 111                perf_mmap__read_done(map);
 112        }
 113
 114out_evlist:
 115        perf_evlist__delete(evlist);
 116out_cpus:
 117        perf_cpu_map__put(cpus);
 118        return err;
 119}
 120