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