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/*
* sampleip: sample instruction pointer and frequency count in a BPF map.
*
* Copyright 2016 Netflix, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*/
#include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <assert.h>
#include <linux/perf_event.h>
#include <linux/ptrace.h>
#include <linux/bpf.h>
#include <sys/ioctl.h>
#include "libbpf.h"
#include "bpf_load.h"
#define DEFAULT_FREQ 99
#define DEFAULT_SECS 5
#define MAX_IPS 8192
#define PAGE_OFFSET 0xffff880000000000
static int nr_cpus;
static void usage(void)
{
printf("USAGE: sampleip [-F freq] [duration]\n");
printf(" -F freq # sample frequency (Hertz), default 99\n");
printf(" duration # sampling duration (seconds), default 5\n");
}
static int sampling_start(int *pmu_fd, int freq)
{
int i;
struct perf_event_attr pe_sample_attr = {
.type = PERF_TYPE_SOFTWARE,
.freq = 1,
.sample_period = freq,
.config = PERF_COUNT_SW_CPU_CLOCK,
.inherit = 1,
};
for (i = 0; i < nr_cpus; i++) {
pmu_fd[i] = perf_event_open(&pe_sample_attr, -1 /* pid */, i,
-1 /* group_fd */, 0 /* flags */);
if (pmu_fd[i] < 0) {
fprintf(stderr, "ERROR: Initializing perf sampling\n");
return 1;
}
assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_SET_BPF,
prog_fd[0]) == 0);
assert(ioctl(pmu_fd[i], PERF_EVENT_IOC_ENABLE, 0) == 0);
}
return 0;
}
static void sampling_end(int *pmu_fd)
{
int i;
for (i = 0; i < nr_cpus; i++)
close(pmu_fd[i]);
}
struct ipcount {
__u64 ip;
__u32 count;
};
/* used for sorting */
struct ipcount counts[MAX_IPS];
static int count_cmp(const void *p1, const void *p2)
{
return ((struct ipcount *)p1)->count - ((struct ipcount *)p2)->count;
}
static void print_ip_map(int fd)
{
struct ksym *sym;
__u64 key, next_key;
__u32 value;
int i, max;
printf("%-19s %-32s %s\n", "ADDR", "KSYM", "COUNT");
/* fetch IPs and counts */
key = 0, i = 0;
while (bpf_map_get_next_key(fd, &key, &next_key) == 0) {
bpf_map_lookup_elem(fd, &next_key, &value);
counts[i].ip = next_key;
counts[i++].count = value;
key = next_key;
}
max = i;
/* sort and print */
qsort(counts, max, sizeof(struct ipcount), count_cmp);
for (i = 0; i < max; i++) {
if (counts[i].ip > PAGE_OFFSET) {
sym = ksym_search(counts[i].ip);
printf("0x%-17llx %-32s %u\n", counts[i].ip, sym->name,
counts[i].count);
} else {
printf("0x%-17llx %-32s %u\n", counts[i].ip, "(user)",
counts[i].count);
}
}
if (max == MAX_IPS) {
printf("WARNING: IP hash was full (max %d entries); ", max);
printf("may have dropped samples\n");
}
}
static void int_exit(int sig)
{
printf("\n");
print_ip_map(map_fd[0]);
exit(0);
}
int main(int argc, char **argv)
{
char filename[256];
int *pmu_fd, opt, freq = DEFAULT_FREQ, secs = DEFAULT_SECS;
/* process arguments */
while ((opt = getopt(argc, argv, "F:h")) != -1) {
switch (opt) {
case 'F':
freq = atoi(optarg);
break;
case 'h':
default:
usage();
return 0;
}
}
if (argc - optind == 1)
secs = atoi(argv[optind]);
if (freq == 0 || secs == 0) {
usage();
return 1;
}
/* initialize kernel symbol translation */
if (load_kallsyms()) {
fprintf(stderr, "ERROR: loading /proc/kallsyms\n");
return 2;
}
/* create perf FDs for each CPU */
nr_cpus = sysconf(_SC_NPROCESSORS_CONF);
pmu_fd = malloc(nr_cpus * sizeof(int));
if (pmu_fd == NULL) {
fprintf(stderr, "ERROR: malloc of pmu_fd\n");
return 1;
}
/* load BPF program */
snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
if (load_bpf_file(filename)) {
fprintf(stderr, "ERROR: loading BPF program (errno %d):\n",
errno);
if (strcmp(bpf_log_buf, "") == 0)
fprintf(stderr, "Try: ulimit -l unlimited\n");
else
fprintf(stderr, "%s", bpf_log_buf);
return 1;
}
signal(SIGINT, int_exit);
/* do sampling */
printf("Sampling at %d Hertz for %d seconds. Ctrl-C also ends.\n",
freq, secs);
if (sampling_start(pmu_fd, freq) != 0)
return 1;
sleep(secs);
sampling_end(pmu_fd);
free(pmu_fd);
/* output sample counts */
print_ip_map(map_fd[0]);
return 0;
}
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