1 /* 2 * sampleip: sample instruction pointer and frequency count in a BPF map. 3 * 4 * Copyright 2016 Netflix, Inc. 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of version 2 of the GNU General Public 8 * License as published by the Free Software Foundation. 9 */ 10 #include <stdio.h> 11 #include <stdlib.h> 12 #include <stdio.h> 13 #include <unistd.h> 14 #include <errno.h> 15 #include <signal.h> 16 #include <string.h> 17 #include <assert.h> 18 #include <linux/perf_event.h> 19 #include <linux/ptrace.h> 20 #include <linux/bpf.h> 21 #include <sys/ioctl.h> 22 #include "libbpf.h" 23 #include "bpf_load.h" 24 25 #define DEFAULT_FREQ 99 26 #define DEFAULT_SECS 5 27 #define MAX_IPS 8192 28 #define PAGE_OFFSET 0xffff880000000000 29 30 static int nr_cpus; 31 32 static void usage(void) 33 { 34 printf("USAGE: sampleip [-F freq] [duration]\n"); 35 printf(" -F freq # sample frequency (Hertz), default 99\n"); 36 printf(" duration # sampling duration (seconds), default 5\n"); 37 } 38 39 static int sampling_start(int *pmu_fd, int freq) 40 { 41 int i; 42 43 struct perf_event_attr pe_sample_attr = { 44 .type = PERF_TYPE_SOFTWARE, 45 .freq = 1, 46 .sample_period = freq, 47 .config = PERF_COUNT_SW_CPU_CLOCK, 48 .inherit = 1, 49 }; 50 51 for (i = 0; i < nr_cpus; i++) { 52 pmu_fd[i] = perf_event_open(&pe_sample_attr, -1 /* pid */, i, 53 -1 /* group_fd */, 0 /* flags */); 54 if (pmu_fd[i] < 0) { 55 fprintf(stderr, "ERROR: Initializing perf sampling\n"); 56 return 1; 57 } 58 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, 59 prog_fd[0]) == 0); 60 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0); 61 } 62 63 return 0; 64 } 65 66 static void sampling_end(int *pmu_fd) 67 { 68 int i; 69 70 for (i = 0; i < nr_cpus; i++) 71 close(pmu_fd[i]); 72 } 73 74 struct ipcount { 75 __u64 ip; 76 __u32 count; 77 }; 78 79 /* used for sorting */ 80 struct ipcount counts[MAX_IPS]; 81 82 static int count_cmp(const void *p1, const void *p2) 83 { 84 return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count; 85 } 86 87 static void print_ip_map(int fd) 88 { 89 struct ksym *sym; 90 __u64 key, next_key; 91 __u32 value; 92 int i, max; 93 94 printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT"); 95 96 /* fetch IPs and counts */ 97 key = 0, i = 0; 98 while (bpf_get_next_key(fd, &key, &next_key) == 0) { 99 bpf_lookup_elem(fd, &next_key, &value); 100 counts[i].ip = next_key; 101 counts[i++].count = value; 102 key = next_key; 103 } 104 max = i; 105 106 /* sort and print */ 107 qsort(counts, max, sizeof(struct ipcount), count_cmp); 108 for (i = 0; i < max; i++) { 109 if (counts[i].ip > PAGE_OFFSET) { 110 sym = ksym_search(counts[i].ip); 111 printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name, 112 counts[i].count); 113 } else { 114 printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)", 115 counts[i].count); 116 } 117 } 118 119 if (max == MAX_IPS) { 120 printf("WARNING: IP hash was full (max %d entries); ", max); 121 printf("may have dropped samples\n"); 122 } 123 } 124 125 static void int_exit(int sig) 126 { 127 printf("\n"); 128 print_ip_map(map_fd[0]); 129 exit(0); 130 } 131 132 int main(int argc, char **argv) 133 { 134 char filename[256]; 135 int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS; 136 137 /* process arguments */ 138 while ((opt = getopt(argc, argv, "F:h")) != -1) { 139 switch (opt) { 140 case 'F': 141 freq = atoi(optarg); 142 break; 143 case 'h': 144 default: 145 usage(); 146 return 0; 147 } 148 } 149 if (argc - optind == 1) 150 secs = atoi(argv[optind]); 151 if (freq == 0 || secs == 0) { 152 usage(); 153 return 1; 154 } 155 156 /* initialize kernel symbol translation */ 157 if (load_kallsyms()) { 158 fprintf(stderr, "ERROR: loading /proc/kallsyms\n"); 159 return 2; 160 } 161 162 /* create perf FDs for each CPU */ 163 nr_cpus = sysconf(_SC_NPROCESSORS_CONF); 164 pmu_fd = malloc(nr_cpus * sizeof(int)); 165 if (pmu_fd == NULL) { 166 fprintf(stderr, "ERROR: malloc of pmu_fd\n"); 167 return 1; 168 } 169 170 /* load BPF program */ 171 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); 172 if (load_bpf_file(filename)) { 173 fprintf(stderr, "ERROR: loading BPF program (errno %d):\n", 174 errno); 175 if (strcmp(bpf_log_buf, "") == 0) 176 fprintf(stderr, "Try: ulimit -l unlimited\n"); 177 else 178 fprintf(stderr, "%s", bpf_log_buf); 179 return 1; 180 } 181 signal(SIGINT, int_exit); 182 183 /* do sampling */ 184 printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n", 185 freq, secs); 186 if (sampling_start(pmu_fd, freq) != 0) 187 return 1; 188 sleep(secs); 189 sampling_end(pmu_fd); 190 free(pmu_fd); 191 192 /* output sample counts */ 193 print_ip_map(map_fd[0]); 194 195 return 0; 196 } 197