tools/perf/tests/backward-ring-buffer.c

   1 /*
   2  * Test backward bit in event attribute, read ring buffer from end to
   3  * beginning
   4  */
   5
   6 #include <perf.h>
   7 #include <evlist.h>
   8 #include <sys/prctl.h>
   9 #include "tests.h"
  10 #include "debug.h"
  11
  12 #define NR_ITERS 111
  13
  14 static void testcase(void)
  15 {
  16         int i;
  17
  18         for (i = 0; i < NR_ITERS; i++) {
  19                 char proc_name[10];
  20
  21                 snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);
  22                 prctl(PR_SET_NAME, proc_name);
  23         }
  24 }
  25
  26 static int count_samples(struct perf_evlist *evlist, int *sample_count,
  27                          int *comm_count)
  28 {
  29         int i;
  30
  31         for (i = 0; i < evlist->nr_mmaps; i++) {
  32                 union perf_event *event;
  33
  34                 perf_evlist__mmap_read_catchup(evlist, i);
  35                 while ((event = perf_evlist__mmap_read_backward(evlist, i)) != NULL) {
  36                         const u32 type = event->header.type;
  37
  38                         switch (type) {
  39                         case PERF_RECORD_SAMPLE:
  40                                 (*sample_count)++;
  41                                 break;
  42                         case PERF_RECORD_COMM:
  43                                 (*comm_count)++;
  44                                 break;
  45                         default:
  46                                 pr_err("Unexpected record of type %d\n", type);
  47                                 return TEST_FAIL;
  48                         }
  49                 }
  50         }
  51         return TEST_OK;
  52 }
  53
  54 static int do_test(struct perf_evlist *evlist, int mmap_pages,
  55                    int *sample_count, int *comm_count)
  56 {
  57         int err;
  58         char sbuf[STRERR_BUFSIZE];
  59
  60         err = perf_evlist__mmap(evlist, mmap_pages, true);
  61         if (err < 0) {
  62                 pr_debug("perf_evlist__mmap: %s\n",
  63                          str_error_r(errno, sbuf, sizeof(sbuf)));
  64                 return TEST_FAIL;
  65         }
  66
  67         perf_evlist__enable(evlist);
  68         testcase();
  69         perf_evlist__disable(evlist);
  70
  71         err = count_samples(evlist, sample_count, comm_count);
  72         perf_evlist__munmap(evlist);
  73         return err;
  74 }
  75
  76
  77 int test__backward_ring_buffer(int subtest __maybe_unused)
  78 {
  79         int ret = TEST_SKIP, err, sample_count = 0, comm_count = 0;
  80         char pid[16], sbuf[STRERR_BUFSIZE];
  81         struct perf_evlist *evlist;
  82         struct perf_evsel *evsel __maybe_unused;
  83         struct parse_events_error parse_error;
  84         struct record_opts opts = {
  85                 .target = {
  86                         .uid = UINT_MAX,
  87                         .uses_mmap = true,
  88                 },
  89                 .freq         = 0,
  90                 .mmap_pages   = 256,
  91                 .default_interval = 1,
  92         };
  93
  94         snprintf(pid, sizeof(pid), "%d", getpid());
  95         pid[sizeof(pid) - 1] = '\0';
  96         opts.target.tid = opts.target.pid = pid;
  97
  98         evlist = perf_evlist__new();
  99         if (!evlist) {
 100                 pr_debug("No ehough memory to create evlist\n");
 101                 return TEST_FAIL;
 102         }
 103
 104         evlist->backward = true;
 105         err = perf_evlist__create_maps(evlist, &opts.target);
 106         if (err < 0) {
 107                 pr_debug("Not enough memory to create thread/cpu maps\n");
 108                 goto out_delete_evlist;
 109         }
 110
 111         bzero(&parse_error, sizeof(parse_error));
 112         err = parse_events(evlist, "syscalls:sys_enter_prctl", &parse_error);
 113         if (err) {
 114                 pr_debug("Failed to parse tracepoint event, try use root\n");
 115                 ret = TEST_SKIP;
 116                 goto out_delete_evlist;
 117         }
 118
 119         perf_evlist__config(evlist, &opts, NULL);
 120
 121         /* Set backward bit, ring buffer should be writing from end */
 122         evlist__for_each_entry(evlist, evsel)
 123                 evsel->attr.write_backward = 1;
 124
 125         err = perf_evlist__open(evlist);
 126         if (err < 0) {
 127                 pr_debug("perf_evlist__open: %s\n",
 128                          str_error_r(errno, sbuf, sizeof(sbuf)));
 129                 goto out_delete_evlist;
 130         }
 131
 132         ret = TEST_FAIL;
 133         err = do_test(evlist, opts.mmap_pages, &sample_count,
 134                       &comm_count);
 135         if (err != TEST_OK)
 136                 goto out_delete_evlist;
 137
 138         if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) {
 139                 pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n",
 140                        sample_count, comm_count);
 141                 goto out_delete_evlist;
 142         }
 143
 144         err = do_test(evlist, 1, &sample_count, &comm_count);
 145         if (err != TEST_OK)
 146                 goto out_delete_evlist;
 147
 148         ret = TEST_OK;
 149 out_delete_evlist:
 150         perf_evlist__delete(evlist);
 151         return ret;
 152 }