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 #include "perf-sys.h" 25 #include "trace_helpers.h" 26 27 #define DEFAULT_FREQ 99 28 #define DEFAULT_SECS 5 29 #define MAX_IPS 8192 30 #define PAGE_OFFSET 0xffff880000000000 31 32 static int nr_cpus; 33 34 static void usage(void) 35 { 36 printf("USAGE: sampleip [-F freq] [duration]\n"); 37 printf(" -F freq # sample frequency (Hertz), default 99\n"); 38 printf(" duration # sampling duration (seconds), default 5\n"); 39 } 40 41 static int sampling_start(int *pmu_fd, int freq) 42 { 43 int i; 44 45 struct perf_event_attr pe_sample_attr = { 46 .type = PERF_TYPE_SOFTWARE, 47 .freq = 1, 48 .sample_period = freq, 49 .config = PERF_COUNT_SW_CPU_CLOCK, 50 .inherit = 1, 51 }; 52 53 for (i = 0; i < nr_cpus; i++) { 54 pmu_fd[i] = sys_perf_event_open(&pe_sample_attr, -1 /* pid */, i, 55 -1 /* group_fd */, 0 /* flags */); 56 if (pmu_fd[i] < 0) { 57 fprintf(stderr, "ERROR: Initializing perf sampling\n"); 58 return 1; 59 } 60 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF, 61 prog_fd[0]) == 0); 62 assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0); 63 } 64 65 return 0; 66 } 67 68 static void sampling_end(int *pmu_fd) 69 { 70 int i; 71 72 for (i = 0; i < nr_cpus; i++) 73 close(pmu_fd[i]); 74 } 75 76 struct ipcount { 77 __u64 ip; 78 __u32 count; 79 }; 80 81 /* used for sorting */ 82 struct ipcount counts[MAX_IPS]; 83 84 static int count_cmp(const void *p1, const void *p2) 85 { 86 return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count; 87 } 88 89 static void print_ip_map(int fd) 90 { 91 struct ksym *sym; 92 __u64 key, next_key; 93 __u32 value; 94 int i, max; 95 96 printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT"); 97 98 /* fetch IPs and counts */ 99 key = 0, i = 0; 100 while (bpf_map_get_next_key(fd, &key, &next_key) == 0) { 101 bpf_map_lookup_elem(fd, &next_key, &value); 102 counts[i].ip = next_key; 103 counts[i++].count = value; 104 key = next_key; 105 } 106 max = i; 107 108 /* sort and print */ 109 qsort(counts, max, sizeof(struct ipcount), count_cmp); 110 for (i = 0; i < max; i++) { 111 if (counts[i].ip > PAGE_OFFSET) { 112 sym = ksym_search(counts[i].ip); 113 printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name, 114 counts[i].count); 115 } else { 116 printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)", 117 counts[i].count); 118 } 119 } 120 121 if (max == MAX_IPS) { 122 printf("WARNING: IP hash was full (max %d entries); ", max); 123 printf("may have dropped samples\n"); 124 } 125 } 126 127 static void int_exit(int sig) 128 { 129 printf("\n"); 130 print_ip_map(map_fd[0]); 131 exit(0); 132 } 133 134 int main(int argc, char **argv) 135 { 136 char filename[256]; 137 int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS; 138 139 /* process arguments */ 140 while ((opt = getopt(argc, argv, "F:h")) != -1) { 141 switch (opt) { 142 case 'F': 143 freq = atoi(optarg); 144 break; 145 case 'h': 146 default: 147 usage(); 148 return 0; 149 } 150 } 151 if (argc - optind == 1) 152 secs = atoi(argv[optind]); 153 if (freq == 0 || secs == 0) { 154 usage(); 155 return 1; 156 } 157 158 /* initialize kernel symbol translation */ 159 if (load_kallsyms()) { 160 fprintf(stderr, "ERROR: loading /proc/kallsyms\n"); 161 return 2; 162 } 163 164 /* create perf FDs for each CPU */ 165 nr_cpus = sysconf(_SC_NPROCESSORS_CONF); 166 pmu_fd = malloc(nr_cpus * sizeof(int)); 167 if (pmu_fd == NULL) { 168 fprintf(stderr, "ERROR: malloc of pmu_fd\n"); 169 return 1; 170 } 171 172 /* load BPF program */ 173 snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]); 174 if (load_bpf_file(filename)) { 175 fprintf(stderr, "ERROR: loading BPF program (errno %d):\n", 176 errno); 177 if (strcmp(bpf_log_buf, "") == 0) 178 fprintf(stderr, "Try: ulimit -l unlimited\n"); 179 else 180 fprintf(stderr, "%s", bpf_log_buf); 181 return 1; 182 } 183 signal(SIGINT, int_exit); 184 signal(SIGTERM, int_exit); 185 186 /* do sampling */ 187 printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n", 188 freq, secs); 189 if (sampling_start(pmu_fd, freq) != 0) 190 return 1; 191 sleep(secs); 192 sampling_end(pmu_fd); 193 free(pmu_fd); 194 195 /* output sample counts */ 196 print_ip_map(map_fd[0]); 197 198 return 0; 199 } 200