172 lines · c
1// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)2// Copyright (c) 2019 Facebook3#include <argp.h>4#include <stdio.h>5#include <stdlib.h>6#include <string.h>7#include <time.h>8#include <bpf/libbpf.h>9#include <bpf/bpf.h>10#include "runqslower.h"11#include "runqslower.skel.h"12 13struct env {14 pid_t pid;15 __u64 min_us;16 bool verbose;17} env = {18 .min_us = 10000,19};20 21const char *argp_program_version = "runqslower 0.1";22const char *argp_program_bug_address = "<bpf@vger.kernel.org>";23const char argp_program_doc[] =24"runqslower Trace long process scheduling delays.\n"25" For Linux, uses eBPF, BPF CO-RE, libbpf, BTF.\n"26"\n"27"This script traces high scheduling delays between tasks being\n"28"ready to run and them running on CPU after that.\n"29"\n"30"USAGE: runqslower [-p PID] [min_us]\n"31"\n"32"EXAMPLES:\n"33" runqslower # trace run queue latency higher than 10000 us (default)\n"34" runqslower 1000 # trace run queue latency higher than 1000 us\n"35" runqslower -p 123 # trace pid 123 only\n";36 37static const struct argp_option opts[] = {38 { "pid", 'p', "PID", 0, "Process PID to trace"},39 { "verbose", 'v', NULL, 0, "Verbose debug output" },40 {},41};42 43static error_t parse_arg(int key, char *arg, struct argp_state *state)44{45 static int pos_args;46 int pid;47 long long min_us;48 49 switch (key) {50 case 'v':51 env.verbose = true;52 break;53 case 'p':54 errno = 0;55 pid = strtol(arg, NULL, 10);56 if (errno || pid <= 0) {57 fprintf(stderr, "Invalid PID: %s\n", arg);58 argp_usage(state);59 }60 env.pid = pid;61 break;62 case ARGP_KEY_ARG:63 if (pos_args++) {64 fprintf(stderr,65 "Unrecognized positional argument: %s\n", arg);66 argp_usage(state);67 }68 errno = 0;69 min_us = strtoll(arg, NULL, 10);70 if (errno || min_us <= 0) {71 fprintf(stderr, "Invalid delay (in us): %s\n", arg);72 argp_usage(state);73 }74 env.min_us = min_us;75 break;76 default:77 return ARGP_ERR_UNKNOWN;78 }79 return 0;80}81 82int libbpf_print_fn(enum libbpf_print_level level,83 const char *format, va_list args)84{85 if (level == LIBBPF_DEBUG && !env.verbose)86 return 0;87 return vfprintf(stderr, format, args);88}89 90void handle_event(void *ctx, int cpu, void *data, __u32 data_sz)91{92 const struct runq_event *e = data;93 struct tm *tm;94 char ts[32];95 time_t t;96 97 time(&t);98 tm = localtime(&t);99 strftime(ts, sizeof(ts), "%H:%M:%S", tm);100 printf("%-8s %-16s %-6d %14llu\n", ts, e->task, e->pid, e->delta_us);101}102 103void handle_lost_events(void *ctx, int cpu, __u64 lost_cnt)104{105 printf("Lost %llu events on CPU #%d!\n", lost_cnt, cpu);106}107 108int main(int argc, char **argv)109{110 static const struct argp argp = {111 .options = opts,112 .parser = parse_arg,113 .doc = argp_program_doc,114 };115 struct perf_buffer *pb = NULL;116 struct runqslower_bpf *obj;117 int err;118 119 err = argp_parse(&argp, argc, argv, 0, NULL, NULL);120 if (err)121 return err;122 123 libbpf_set_print(libbpf_print_fn);124 125 /* Use libbpf 1.0 API mode */126 libbpf_set_strict_mode(LIBBPF_STRICT_ALL);127 128 obj = runqslower_bpf__open();129 if (!obj) {130 fprintf(stderr, "failed to open and/or load BPF object\n");131 return 1;132 }133 134 /* initialize global data (filtering options) */135 obj->rodata->targ_pid = env.pid;136 obj->rodata->min_us = env.min_us;137 138 err = runqslower_bpf__load(obj);139 if (err) {140 fprintf(stderr, "failed to load BPF object: %d\n", err);141 goto cleanup;142 }143 144 err = runqslower_bpf__attach(obj);145 if (err) {146 fprintf(stderr, "failed to attach BPF programs\n");147 goto cleanup;148 }149 150 printf("Tracing run queue latency higher than %llu us\n", env.min_us);151 printf("%-8s %-16s %-6s %14s\n", "TIME", "COMM", "PID", "LAT(us)");152 153 pb = perf_buffer__new(bpf_map__fd(obj->maps.events), 64,154 handle_event, handle_lost_events, NULL, NULL);155 err = libbpf_get_error(pb);156 if (err) {157 pb = NULL;158 fprintf(stderr, "failed to open perf buffer: %d\n", err);159 goto cleanup;160 }161 162 while ((err = perf_buffer__poll(pb, 100)) >= 0)163 ;164 printf("Error polling perf buffer: %d\n", err);165 166cleanup:167 perf_buffer__free(pb);168 runqslower_bpf__destroy(obj);169 170 return err != 0;171}172