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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
// Copyright (c) 2019 Facebook
#include <argp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/resource.h>
#include <time.h>
#include <libbpf.h>
#include <bpf.h>
#include "runqslower.h"
#include "runqslower.skel.h"
struct env {
pid_t pid;
__u64 min_us;
bool verbose;
} env = {
.min_us = 10000,
};
const char *argp_program_version = "runqslower 0.1";
const char *argp_program_bug_address = "<bpf@vger.kernel.org>";
const char argp_program_doc[] =
"runqslower Trace long process scheduling delays.\n"
" For Linux, uses eBPF, BPF CO-RE, libbpf, BTF.\n"
"\n"
"This script traces high scheduling delays between tasks being\n"
"ready to run and them running on CPU after that.\n"
"\n"
"USAGE: runqslower [-p PID] [min_us]\n"
"\n"
"EXAMPLES:\n"
" runqslower # trace run queue latency higher than 10000 us (default)\n"
" runqslower 1000 # trace run queue latency higher than 1000 us\n"
" runqslower -p 123 # trace pid 123 only\n";
static const struct argp_option opts[] = {
{ "pid", 'p', "PID", 0, "Process PID to trace"},
{ "verbose", 'v', NULL, 0, "Verbose debug output" },
{},
};
static error_t parse_arg(int key, char *arg, struct argp_state *state)
{
static int pos_args;
int pid;
long long min_us;
switch (key) {
case 'v':
env.verbose = true;
break;
case 'p':
errno = 0;
pid = strtol(arg, NULL, 10);
if (errno || pid <= 0) {
fprintf(stderr, "Invalid PID: %s\n", arg);
argp_usage(state);
}
env.pid = pid;
break;
case ARGP_KEY_ARG:
if (pos_args++) {
fprintf(stderr,
"Unrecognized positional argument: %s\n", arg);
argp_usage(state);
}
errno = 0;
min_us = strtoll(arg, NULL, 10);
if (errno || min_us <= 0) {
fprintf(stderr, "Invalid delay (in us): %s\n", arg);
argp_usage(state);
}
env.min_us = min_us;
break;
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
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 int bump_memlock_rlimit(void)
{
struct rlimit rlim_new = {
.rlim_cur = RLIM_INFINITY,
.rlim_max = RLIM_INFINITY,
};
return setrlimit(RLIMIT_MEMLOCK, &rlim_new);
}
void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)
{
const struct event *e = data;
struct tm *tm;
char ts[32];
time_t t;
time(&t);
tm = localtime(&t);
strftime(ts, sizeof(ts), "%H:%M:%S", tm);
printf("%-8s %-16s %-6d %14llu\n", ts, e->task, e->pid, e->delta_us);
}
void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)
{
printf("Lost %llu events on CPU #%d!\n", lost_cnt, cpu);
}
int main(int argc, char **argv)
{
static const struct argp argp = {
.options = opts,
.parser = parse_arg,
.doc = argp_program_doc,
};
struct perf_buffer_opts pb_opts;
struct perf_buffer *pb = NULL;
struct runqslower_bpf *obj;
int err;
err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
if (err)
return err;
libbpf_set_print(libbpf_print_fn);
err = bump_memlock_rlimit();
if (err) {
fprintf(stderr, "failed to increase rlimit: %d", err);
return 1;
}
obj = runqslower_bpf__open();
if (!obj) {
fprintf(stderr, "failed to open and/or load BPF object\n");
return 1;
}
/* initialize global data (filtering options) */
obj->rodata->targ_pid = env.pid;
obj->rodata->min_us = env.min_us;
err = runqslower_bpf__load(obj);
if (err) {
fprintf(stderr, "failed to load BPF object: %d\n", err);
goto cleanup;
}
err = runqslower_bpf__attach(obj);
if (err) {
fprintf(stderr, "failed to attach BPF programs\n");
goto cleanup;
}
printf("Tracing run queue latency higher than %llu us\n", env.min_us);
printf("%-8s %-16s %-6s %14s\n", "TIME", "COMM", "PID", "LAT(us)");
pb_opts.sample_cb = handle_event;
pb_opts.lost_cb = handle_lost_events;
pb = perf_buffer__new(bpf_map__fd(obj->maps.events), 64, &pb_opts);
err = libbpf_get_error(pb);
if (err) {
pb = NULL;
fprintf(stderr, "failed to open perf buffer: %d\n", err);
goto cleanup;
}
while ((err = perf_buffer__poll(pb, 100)) >= 0)
;
printf("Error polling perf buffer: %d\n", err);
cleanup:
perf_buffer__free(pb);
runqslower_bpf__destroy(obj);
return err != 0;
}
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