LXR linux/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
  14static 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
  26static 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_mmap__read_catchup(&evlist->backward_mmap[i]);
  35                while ((event = perf_mmap__read_backward(&evlist->backward_mmap[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
  54static 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
  77int 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        err = perf_evlist__create_maps(evlist, &opts.target);
 105        if (err < 0) {
 106                pr_debug("Not enough memory to create thread/cpu maps\n");
 107                goto out_delete_evlist;
 108        }
 109
 110        bzero(&parse_error, sizeof(parse_error));
 111        /*
 112         * Set backward bit, ring buffer should be writing from end. Record
 113         * it in aux evlist
 114         */
 115        err = parse_events(evlist, "syscalls:sys_enter_prctl/overwrite/", &parse_error);
 116        if (err) {
 117                pr_debug("Failed to parse tracepoint event, try use root\n");
 118                ret = TEST_SKIP;
 119                goto out_delete_evlist;
 120        }
 121
 122        perf_evlist__config(evlist, &opts, NULL);
 123
 124        err = perf_evlist__open(evlist);
 125        if (err < 0) {
 126                pr_debug("perf_evlist__open: %s\n",
 127                         str_error_r(errno, sbuf, sizeof(sbuf)));
 128                goto out_delete_evlist;
 129        }
 130
 131        ret = TEST_FAIL;
 132        err = do_test(evlist, opts.mmap_pages, &sample_count,
 133                      &comm_count);
 134        if (err != TEST_OK)
 135                goto out_delete_evlist;
 136
 137        if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) {
 138                pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n",
 139                       sample_count, comm_count);
 140                goto out_delete_evlist;
 141        }
 142
 143        err = do_test(evlist, 1, &sample_count, &comm_count);
 144        if (err != TEST_OK)
 145                goto out_delete_evlist;
 146
 147        ret = TEST_OK;
 148out_delete_evlist:
 149        perf_evlist__delete(evlist);
 150        return ret;
 151}
 152