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cpufreq.c
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cpufreq.c
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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
// Copyright (c) 2020 Wenbo Zhang
//
// Based on cpufreq(8) from BPF-Perf-Tools-Book by Brendan Gregg.
// 10-OCT-2020 Wenbo Zhang Created this.
#include <argp.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <linux/perf_event.h>
#include <asm/unistd.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include "cpufreq.h"
#include "cpufreq.skel.h"
#include "trace_helpers.h"
static struct env {
int duration;
int freq;
bool verbose;
} env = {
.duration = -1,
.freq = 99,
};
const char *argp_program_version = "cpufreq 0.1";
const char *argp_program_bug_address =
"https://github.com/iovisor/bcc/tree/master/libbpf-tools";
const char argp_program_doc[] =
"Sampling CPU freq system-wide & by process. Ctrl-C to end.\n"
"\n"
"USAGE: cpufreq [--help] [-d DURATION] [-f FREQUENCY]\n"
"\n"
"EXAMPLES:\n"
" cpufreq # sample CPU freq at 99HZ (default)\n"
" cpufreq -d 5 # sample for 5 seconds only\n"
" cpufreq -f 199 # sample CPU freq at 199HZ\n";
static const struct argp_option opts[] = {
{ "duration", 'd', "DURATION", 0, "Duration to sample in seconds" },
{ "frequency", 'f', "FREQUENCY", 0, "Sample with a certain frequency" },
{ "verbose", 'v', NULL, 0, "Verbose debug output" },
{ NULL, 'h', NULL, OPTION_HIDDEN, "Show the full help" },
{},
};
static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
switch (key) {
case 'h':
argp_state_help(state, stderr, ARGP_HELP_STD_HELP);
break;
case 'v':
env.verbose = true;
break;
case 'd':
errno = 0;
env.duration = strtol(arg, NULL, 10);
if (errno || env.duration <= 0) {
fprintf(stderr, "Invalid duration: %s\n", arg);
argp_usage(state);
}
break;
case 'f':
errno = 0;
env.freq = strtol(arg, NULL, 10);
if (errno || env.freq <= 0) {
fprintf(stderr, "Invalid freq (in HZ): %s\n", arg);
argp_usage(state);
}
break;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
static int nr_cpus;
static int open_and_attach_perf_event(int freq, struct bpf_program *prog,
struct bpf_link *links[])
{
struct perf_event_attr attr = {
.type = PERF_TYPE_SOFTWARE,
.freq = 1,
.sample_period = freq,
.config = PERF_COUNT_SW_CPU_CLOCK,
};
int i, fd;
for (i = 0; i < nr_cpus; i++) {
fd = syscall(__NR_perf_event_open, &attr, -1, i, -1, 0);
if (fd < 0) {
/* Ignore CPU that is offline */
if (errno == ENODEV)
continue;
fprintf(stderr, "failed to init perf sampling: %s\n",
strerror(errno));
return -1;
}
links[i] = bpf_program__attach_perf_event(prog, fd);
if (!links[i]) {
fprintf(stderr, "failed to attach perf event on cpu: %d\n", i);
close(fd);
return -1;
}
}
return 0;
}
static int libbpf_print_fn(enum libbpf_print_level level, const char *format, va_list args)
{
if (level == LIBBPF_DEBUG && !env.verbose)
return 0;
return vfprintf(stderr, format, args);
}
static void sig_handler(int sig)
{
}
static int init_freqs_hmz(__u32 *freqs_mhz, int nr_cpus)
{
char path[64];
FILE *f;
int i;
for (i = 0; i < nr_cpus; i++) {
snprintf(path, sizeof(path),
"/sys/devices/system/cpu/cpu%d/cpufreq/scaling_cur_freq",
i);
f = fopen(path, "r");
if (!f) {
fprintf(stderr, "failed to open '%s': %s\n", path,
strerror(errno));
return -1;
}
if (fscanf(f, "%u\n", &freqs_mhz[i]) != 1) {
fprintf(stderr, "failed to parse '%s': %s\n", path,
strerror(errno));
fclose(f);
return -1;
}
fclose(f);
}
return 0;
}
static void print_linear_hists(struct bpf_map *hists,
struct cpufreq_bpf__bss *bss)
{
struct hkey lookup_key = {}, next_key;
int err, fd = bpf_map__fd(hists);
struct hist hist;
while (!bpf_map_get_next_key(fd, &lookup_key, &next_key)) {
err = bpf_map_lookup_elem(fd, &next_key, &hist);
if (err < 0) {
fprintf(stderr, "failed to lookup hist: %d\n", err);
return;
}
print_linear_hist(hist.slots, MAX_SLOTS, 0, HIST_STEP_SIZE,
next_key.comm);
printf("\n");
lookup_key = next_key;
}
printf("\n");
print_linear_hist(bss->syswide.slots, MAX_SLOTS, 0, HIST_STEP_SIZE,
"syswide");
}
int main(int argc, char **argv)
{
static const struct argp argp = {
.options = opts,
.parser = parse_arg,
.doc = argp_program_doc,
};
struct bpf_link *links[MAX_CPU_NR] = {};
struct cpufreq_bpf *obj;
int err, i;
err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
if (err)
return err;
libbpf_set_strict_mode(LIBBPF_STRICT_ALL);
libbpf_set_print(libbpf_print_fn);
nr_cpus = libbpf_num_possible_cpus();
if (nr_cpus < 0) {
fprintf(stderr, "failed to get # of possible cpus: '%s'!\n",
strerror(-nr_cpus));
return 1;
}
if (nr_cpus > MAX_CPU_NR) {
fprintf(stderr, "the number of cpu cores is too big, please "
"increase MAX_CPU_NR's value and recompile");
return 1;
}
obj = cpufreq_bpf__open_and_load();
if (!obj) {
fprintf(stderr, "failed to open and/or load BPF object\n");
return 1;
}
if (!obj->bss) {
fprintf(stderr, "Memory-mapping BPF maps is supported starting from Linux 5.7, please upgrade.\n");
goto cleanup;
}
err = init_freqs_hmz(obj->bss->freqs_mhz, nr_cpus);
if (err) {
fprintf(stderr, "failed to init freqs\n");
goto cleanup;
}
err = open_and_attach_perf_event(env.freq, obj->progs.do_sample, links);
if (err)
goto cleanup;
err = cpufreq_bpf__attach(obj);
if (err) {
fprintf(stderr, "failed to attach BPF programs\n");
goto cleanup;
}
printf("Sampling CPU freq system-wide & by process. Ctrl-C to end.\n");
signal(SIGINT, sig_handler);
/*
* We'll get sleep interrupted when someone presses Ctrl-C (which will
* be "handled" with noop by sig_handler).
*/
sleep(env.duration);
printf("\n");
print_linear_hists(obj->maps.hists, obj->bss);
cleanup:
for (i = 0; i < nr_cpus; i++)
bpf_link__destroy(links[i]);
cpufreq_bpf__destroy(obj);
return err != 0;
}