root/samples/bpf/trace_output_user.c

DEFINITIONS

1. time_get_ns
2. print_bpf_output
3. main

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <stdio.h>
   3 #include <unistd.h>
   4 #include <stdlib.h>
   5 #include <stdbool.h>
   6 #include <string.h>
   7 #include <fcntl.h>
   8 #include <poll.h>
   9 #include <linux/perf_event.h>
  10 #include <linux/bpf.h>
  11 #include <errno.h>
  12 #include <assert.h>
  13 #include <sys/syscall.h>
  14 #include <sys/ioctl.h>
  15 #include <sys/mman.h>
  16 #include <time.h>
  17 #include <signal.h>
  18 #include <libbpf.h>
  19 #include "bpf_load.h"
  20 #include "perf-sys.h"
  21 
  22 static __u64 time_get_ns(void)
  23 {
  24         struct timespec ts;
  25 
  26         clock_gettime(CLOCK_MONOTONIC, &ts);
  27         return ts.tv_sec * 1000000000ull + ts.tv_nsec;
  28 }
  29 
  30 static __u64 start_time;
  31 static __u64 cnt;
  32 
  33 #define MAX_CNT 100000ll
  34 
  35 static void print_bpf_output(void *ctx, int cpu, void *data, __u32 size)
  36 {
  37         struct {
  38                 __u64 pid;
  39                 __u64 cookie;
  40         } *e = data;
  41 
  42         if (e->cookie != 0x12345678) {
  43                 printf("BUG pid %llx cookie %llx sized %d\n",
  44                        e->pid, e->cookie, size);
  45                 return;
  46         }
  47 
  48         cnt++;
  49 
  50         if (cnt == MAX_CNT) {
  51                 printf("recv %lld events per sec\n",
  52                        MAX_CNT * 1000000000ll / (time_get_ns() - start_time));
  53                 return;
  54         }
  55 }
  56 
  57 int main(int argc, char **argv)
  58 {
  59         struct perf_buffer_opts pb_opts = {};
  60         struct perf_buffer *pb;
  61         char filename[256];
  62         FILE *f;
  63         int ret;
  64 
  65         snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
  66 
  67         if (load_bpf_file(filename)) {
  68                 printf("%s", bpf_log_buf);
  69                 return 1;
  70         }
  71 
  72         pb_opts.sample_cb = print_bpf_output;
  73         pb = perf_buffer__new(map_fd[0], 8, &pb_opts);
  74         ret = libbpf_get_error(pb);
  75         if (ret) {
  76                 printf("failed to setup perf_buffer: %d\n", ret);
  77                 return 1;
  78         }
  79 
  80         f = popen("taskset 1 dd if=/dev/zero of=/dev/null", "r");
  81         (void) f;
  82 
  83         start_time = time_get_ns();
  84         while ((ret = perf_buffer__poll(pb, 1000)) >= 0 && cnt < MAX_CNT) {
  85         }
  86         kill(0, SIGINT);
  87         return ret;
  88 }