1// SPDX-License-Identifier: GPL-2.0 2/* 3 * Copyright (C) 2021 Red Hat Inc, Daniel Bristot de Oliveira <bristot@kernel.org> 4 */ 5 6#define _GNU_SOURCE 7#include <getopt.h> 8#include <stdlib.h> 9#include <string.h> 10#include <signal.h> 11#include <unistd.h> 12#include <stdio.h> 13#include <time.h> 14#include <sched.h> 15 16#include "osnoise.h" 17#include "utils.h" 18 19enum osnoise_mode { 20 MODE_OSNOISE = 0, 21 MODE_HWNOISE 22}; 23 24/* 25 * osnoise top parameters 26 */ 27struct osnoise_top_params { 28 char *cpus; 29 cpu_set_t monitored_cpus; 30 char *trace_output; 31 char *cgroup_name; 32 unsigned long long runtime; 33 unsigned long long period; 34 long long threshold; 35 long long stop_us; 36 long long stop_total_us; 37 int sleep_time; 38 int duration; 39 int quiet; 40 int set_sched; 41 int cgroup; 42 int hk_cpus; 43 cpu_set_t hk_cpu_set; 44 struct sched_attr sched_param; 45 struct trace_events *events; 46 enum osnoise_mode mode; 47}; 48 49struct osnoise_top_cpu { 50 unsigned long long sum_runtime; 51 unsigned long long sum_noise; 52 unsigned long long max_noise; 53 unsigned long long max_sample; 54 55 unsigned long long hw_count; 56 unsigned long long nmi_count; 57 unsigned long long irq_count; 58 unsigned long long softirq_count; 59 unsigned long long thread_count; 60 61 int sum_cycles; 62}; 63 64struct osnoise_top_data { 65 struct osnoise_top_cpu *cpu_data; 66 int nr_cpus; 67}; 68 69/* 70 * osnoise_free_top - free runtime data 71 */ 72static void 73osnoise_free_top(struct osnoise_top_data *data) 74{ 75 free(data->cpu_data); 76 free(data); 77} 78 79/* 80 * osnoise_alloc_histogram - alloc runtime data 81 */ 82static struct osnoise_top_data *osnoise_alloc_top(int nr_cpus) 83{ 84 struct osnoise_top_data *data; 85 86 data = calloc(1, sizeof(*data)); 87 if (!data) 88 return NULL; 89 90 data->nr_cpus = nr_cpus; 91 92 /* one set of histograms per CPU */ 93 data->cpu_data = calloc(1, sizeof(*data->cpu_data) * nr_cpus); 94 if (!data->cpu_data) 95 goto cleanup; 96 97 return data; 98 99cleanup: 100 osnoise_free_top(data); 101 return NULL; 102} 103 104/* 105 * osnoise_top_handler - this is the handler for osnoise tracer events 106 */ 107static int 108osnoise_top_handler(struct trace_seq *s, struct tep_record *record, 109 struct tep_event *event, void *context) 110{ 111 struct trace_instance *trace = context; 112 struct osnoise_tool *tool; 113 unsigned long long val; 114 struct osnoise_top_cpu *cpu_data; 115 struct osnoise_top_data *data; 116 int cpu = record->cpu; 117 118 tool = container_of(trace, struct osnoise_tool, trace); 119 120 data = tool->data; 121 cpu_data = &data->cpu_data[cpu]; 122 123 cpu_data->sum_cycles++; 124 125 tep_get_field_val(s, event, "runtime", record, &val, 1); 126 update_sum(&cpu_data->sum_runtime, &val); 127 128 tep_get_field_val(s, event, "noise", record, &val, 1); 129 update_max(&cpu_data->max_noise, &val); 130 update_sum(&cpu_data->sum_noise, &val); 131 132 tep_get_field_val(s, event, "max_sample", record, &val, 1); 133 update_max(&cpu_data->max_sample, &val); 134 135 tep_get_field_val(s, event, "hw_count", record, &val, 1); 136 update_sum(&cpu_data->hw_count, &val); 137 138 tep_get_field_val(s, event, "nmi_count", record, &val, 1); 139 update_sum(&cpu_data->nmi_count, &val); 140 141 tep_get_field_val(s, event, "irq_count", record, &val, 1); 142 update_sum(&cpu_data->irq_count, &val); 143 144 tep_get_field_val(s, event, "softirq_count", record, &val, 1); 145 update_sum(&cpu_data->softirq_count, &val); 146 147 tep_get_field_val(s, event, "thread_count", record, &val, 1); 148 update_sum(&cpu_data->thread_count, &val); 149 150 return 0; 151} 152 153/* 154 * osnoise_top_header - print the header of the tool output 155 */ 156static void osnoise_top_header(struct osnoise_tool *top) 157{ 158 struct osnoise_top_params *params = top->params; 159 struct trace_seq *s = top->trace.seq; 160 char duration[26]; 161 162 get_duration(top->start_time, duration, sizeof(duration)); 163 164 trace_seq_printf(s, "\033[2;37;40m"); 165 trace_seq_printf(s, " "); 166 167 if (params->mode == MODE_OSNOISE) { 168 trace_seq_printf(s, "Operating System Noise"); 169 trace_seq_printf(s, " "); 170 } else if (params->mode == MODE_HWNOISE) { 171 trace_seq_printf(s, "Hardware-related Noise"); 172 } 173 174 trace_seq_printf(s, " "); 175 trace_seq_printf(s, "\033[0;0;0m"); 176 trace_seq_printf(s, "\n"); 177 178 trace_seq_printf(s, "duration: %9s | time is in us\n", duration); 179 180 trace_seq_printf(s, "\033[2;30;47m"); 181 trace_seq_printf(s, "CPU Period Runtime "); 182 trace_seq_printf(s, " Noise "); 183 trace_seq_printf(s, " %% CPU Aval "); 184 trace_seq_printf(s, " Max Noise Max Single "); 185 trace_seq_printf(s, " HW NMI"); 186 187 if (params->mode == MODE_HWNOISE) 188 goto eol; 189 190 trace_seq_printf(s, " IRQ Softirq Thread"); 191 192eol: 193 trace_seq_printf(s, "\033[0;0;0m"); 194 trace_seq_printf(s, "\n"); 195} 196 197/* 198 * clear_terminal - clears the output terminal 199 */ 200static void clear_terminal(struct trace_seq *seq) 201{ 202 if (!config_debug) 203 trace_seq_printf(seq, "\033c"); 204} 205 206/* 207 * osnoise_top_print - prints the output of a given CPU 208 */ 209static void osnoise_top_print(struct osnoise_tool *tool, int cpu) 210{ 211 struct osnoise_top_params *params = tool->params; 212 struct trace_seq *s = tool->trace.seq; 213 struct osnoise_top_cpu *cpu_data; 214 struct osnoise_top_data *data; 215 int percentage; 216 int decimal; 217 218 data = tool->data; 219 cpu_data = &data->cpu_data[cpu]; 220 221 if (!cpu_data->sum_runtime) 222 return; 223 224 percentage = ((cpu_data->sum_runtime - cpu_data->sum_noise) * 10000000) 225 / cpu_data->sum_runtime; 226 decimal = percentage % 100000; 227 percentage = percentage / 100000; 228 229 trace_seq_printf(s, "%3d #%-6d %12llu ", cpu, cpu_data->sum_cycles, cpu_data->sum_runtime); 230 trace_seq_printf(s, "%12llu ", cpu_data->sum_noise); 231 trace_seq_printf(s, " %3d.%05d", percentage, decimal); 232 trace_seq_printf(s, "%12llu %12llu", cpu_data->max_noise, cpu_data->max_sample); 233 234 trace_seq_printf(s, "%12llu ", cpu_data->hw_count); 235 trace_seq_printf(s, "%12llu ", cpu_data->nmi_count); 236 237 if (params->mode == MODE_HWNOISE) { 238 trace_seq_printf(s, "\n"); 239 return; 240 } 241 242 trace_seq_printf(s, "%12llu ", cpu_data->irq_count); 243 trace_seq_printf(s, "%12llu ", cpu_data->softirq_count); 244 trace_seq_printf(s, "%12llu\n", cpu_data->thread_count); 245} 246 247/* 248 * osnoise_print_stats - print data for all cpus 249 */ 250static void 251osnoise_print_stats(struct osnoise_top_params *params, struct osnoise_tool *top) 252{ 253 struct trace_instance *trace = &top->trace; 254 static int nr_cpus = -1; 255 int i; 256 257 if (nr_cpus == -1) 258 nr_cpus = sysconf(_SC_NPROCESSORS_CONF); 259 260 if (!params->quiet) 261 clear_terminal(trace->seq); 262 263 osnoise_top_header(top); 264 265 for (i = 0; i < nr_cpus; i++) { 266 if (params->cpus && !CPU_ISSET(i, ¶ms->monitored_cpus)) 267 continue; 268 osnoise_top_print(top, i); 269 } 270 271 trace_seq_do_printf(trace->seq); 272 trace_seq_reset(trace->seq); 273} 274 275/* 276 * osnoise_top_usage - prints osnoise top usage message 277 */ 278static void osnoise_top_usage(struct osnoise_top_params *params, char *usage) 279{ 280 int i; 281 282 static const char * const msg[] = { 283 " [-h] [-q] [-D] [-d s] [-a us] [-p us] [-r us] [-s us] [-S us] \\", 284 " [-T us] [-t[=file]] [-e sys[:event]] [--filter <filter>] [--trigger <trigger>] \\", 285 " [-c cpu-list] [-H cpu-list] [-P priority] [-C[=cgroup_name]]", 286 "", 287 " -h/--help: print this menu", 288 " -a/--auto: set automatic trace mode, stopping the session if argument in us sample is hit", 289 " -p/--period us: osnoise period in us", 290 " -r/--runtime us: osnoise runtime in us", 291 " -s/--stop us: stop trace if a single sample is higher than the argument in us", 292 " -S/--stop-total us: stop trace if the total sample is higher than the argument in us", 293 " -T/--threshold us: the minimum delta to be considered a noise", 294 " -c/--cpus cpu-list: list of cpus to run osnoise threads", 295 " -H/--house-keeping cpus: run rtla control threads only on the given cpus", 296 " -C/--cgroup[=cgroup_name]: set cgroup, if no cgroup_name is passed, the rtla's cgroup will be inherited", 297 " -d/--duration time[s|m|h|d]: duration of the session", 298 " -D/--debug: print debug info", 299 " -t/--trace[=file]: save the stopped trace to [file|osnoise_trace.txt]", 300 " -e/--event <sys:event>: enable the <sys:event> in the trace instance, multiple -e are allowed", 301 " --filter <filter>: enable a trace event filter to the previous -e event", 302 " --trigger <trigger>: enable a trace event trigger to the previous -e event", 303 " -q/--quiet print only a summary at the end", 304 " -P/--priority o:prio|r:prio|f:prio|d:runtime:period : set scheduling parameters", 305 " o:prio - use SCHED_OTHER with prio", 306 " r:prio - use SCHED_RR with prio", 307 " f:prio - use SCHED_FIFO with prio", 308 " d:runtime[us|ms|s]:period[us|ms|s] - use SCHED_DEADLINE with runtime and period", 309 " in nanoseconds", 310 NULL, 311 }; 312 313 if (usage) 314 fprintf(stderr, "%s\n", usage); 315 316 if (params->mode == MODE_OSNOISE) { 317 fprintf(stderr, 318 "rtla osnoise top: a per-cpu summary of the OS noise (version %s)\n", 319 VERSION); 320 321 fprintf(stderr, " usage: rtla osnoise [top]"); 322 } 323 324 if (params->mode == MODE_HWNOISE) { 325 fprintf(stderr, 326 "rtla hwnoise: a summary of hardware-related noise (version %s)\n", 327 VERSION); 328 329 fprintf(stderr, " usage: rtla hwnoise"); 330 } 331 332 for (i = 0; msg[i]; i++) 333 fprintf(stderr, "%s\n", msg[i]); 334 335 if (usage) 336 exit(EXIT_FAILURE); 337 338 exit(EXIT_SUCCESS); 339} 340 341/* 342 * osnoise_top_parse_args - allocs, parse and fill the cmd line parameters 343 */ 344struct osnoise_top_params *osnoise_top_parse_args(int argc, char **argv) 345{ 346 struct osnoise_top_params *params; 347 struct trace_events *tevent; 348 int retval; 349 int c; 350 351 params = calloc(1, sizeof(*params)); 352 if (!params) 353 exit(1); 354 355 if (strcmp(argv[0], "hwnoise") == 0) { 356 params->mode = MODE_HWNOISE; 357 /* 358 * Reduce CPU usage for 75% to avoid killing the system. 359 */ 360 params->runtime = 750000; 361 params->period = 1000000; 362 } 363 364 while (1) { 365 static struct option long_options[] = { 366 {"auto", required_argument, 0, 'a'}, 367 {"cpus", required_argument, 0, 'c'}, 368 {"cgroup", optional_argument, 0, 'C'}, 369 {"debug", no_argument, 0, 'D'}, 370 {"duration", required_argument, 0, 'd'}, 371 {"event", required_argument, 0, 'e'}, 372 {"house-keeping", required_argument, 0, 'H'}, 373 {"help", no_argument, 0, 'h'}, 374 {"period", required_argument, 0, 'p'}, 375 {"priority", required_argument, 0, 'P'}, 376 {"quiet", no_argument, 0, 'q'}, 377 {"runtime", required_argument, 0, 'r'}, 378 {"stop", required_argument, 0, 's'}, 379 {"stop-total", required_argument, 0, 'S'}, 380 {"threshold", required_argument, 0, 'T'}, 381 {"trace", optional_argument, 0, 't'}, 382 {"trigger", required_argument, 0, '0'}, 383 {"filter", required_argument, 0, '1'}, 384 {0, 0, 0, 0} 385 }; 386 387 /* getopt_long stores the option index here. */ 388 int option_index = 0; 389 390 c = getopt_long(argc, argv, "a:c:C::d:De:hH:p:P:qr:s:S:t::T:0:1:", 391 long_options, &option_index); 392 393 /* Detect the end of the options. */ 394 if (c == -1) 395 break; 396 397 switch (c) { 398 case 'a': 399 /* set sample stop to auto_thresh */ 400 params->stop_us = get_llong_from_str(optarg); 401 402 /* set sample threshold to 1 */ 403 params->threshold = 1; 404 405 /* set trace */ 406 params->trace_output = "osnoise_trace.txt"; 407 408 break; 409 case 'c': 410 retval = parse_cpu_set(optarg, ¶ms->monitored_cpus); 411 if (retval) 412 osnoise_top_usage(params, "\nInvalid -c cpu list\n"); 413 params->cpus = optarg; 414 break; 415 case 'C': 416 params->cgroup = 1; 417 if (!optarg) { 418 /* will inherit this cgroup */ 419 params->cgroup_name = NULL; 420 } else if (*optarg == '=') { 421 /* skip the = */ 422 params->cgroup_name = ++optarg; 423 } 424 break; 425 case 'D': 426 config_debug = 1; 427 break; 428 case 'd': 429 params->duration = parse_seconds_duration(optarg); 430 if (!params->duration) 431 osnoise_top_usage(params, "Invalid -D duration\n"); 432 break; 433 case 'e': 434 tevent = trace_event_alloc(optarg); 435 if (!tevent) { 436 err_msg("Error alloc trace event"); 437 exit(EXIT_FAILURE); 438 } 439 440 if (params->events) 441 tevent->next = params->events; 442 params->events = tevent; 443 444 break; 445 case 'h': 446 case '?': 447 osnoise_top_usage(params, NULL); 448 break; 449 case 'H': 450 params->hk_cpus = 1; 451 retval = parse_cpu_set(optarg, ¶ms->hk_cpu_set); 452 if (retval) { 453 err_msg("Error parsing house keeping CPUs\n"); 454 exit(EXIT_FAILURE); 455 } 456 break; 457 case 'p': 458 params->period = get_llong_from_str(optarg); 459 if (params->period > 10000000) 460 osnoise_top_usage(params, "Period longer than 10 s\n"); 461 break; 462 case 'P': 463 retval = parse_prio(optarg, ¶ms->sched_param); 464 if (retval == -1) 465 osnoise_top_usage(params, "Invalid -P priority"); 466 params->set_sched = 1; 467 break; 468 case 'q': 469 params->quiet = 1; 470 break; 471 case 'r': 472 params->runtime = get_llong_from_str(optarg); 473 if (params->runtime < 100) 474 osnoise_top_usage(params, "Runtime shorter than 100 us\n"); 475 break; 476 case 's': 477 params->stop_us = get_llong_from_str(optarg); 478 break; 479 case 'S': 480 params->stop_total_us = get_llong_from_str(optarg); 481 break; 482 case 't': 483 if (optarg) 484 /* skip = */ 485 params->trace_output = &optarg[1]; 486 else 487 params->trace_output = "osnoise_trace.txt"; 488 break; 489 case 'T': 490 params->threshold = get_llong_from_str(optarg); 491 break; 492 case '0': /* trigger */ 493 if (params->events) { 494 retval = trace_event_add_trigger(params->events, optarg); 495 if (retval) { 496 err_msg("Error adding trigger %s\n", optarg); 497 exit(EXIT_FAILURE); 498 } 499 } else { 500 osnoise_top_usage(params, "--trigger requires a previous -e\n"); 501 } 502 break; 503 case '1': /* filter */ 504 if (params->events) { 505 retval = trace_event_add_filter(params->events, optarg); 506 if (retval) { 507 err_msg("Error adding filter %s\n", optarg); 508 exit(EXIT_FAILURE); 509 } 510 } else { 511 osnoise_top_usage(params, "--filter requires a previous -e\n"); 512 } 513 break; 514 default: 515 osnoise_top_usage(params, "Invalid option"); 516 } 517 } 518 519 if (geteuid()) { 520 err_msg("osnoise needs root permission\n"); 521 exit(EXIT_FAILURE); 522 } 523 524 return params; 525} 526 527/* 528 * osnoise_top_apply_config - apply the top configs to the initialized tool 529 */ 530static int 531osnoise_top_apply_config(struct osnoise_tool *tool, struct osnoise_top_params *params) 532{ 533 int retval; 534 535 if (!params->sleep_time) 536 params->sleep_time = 1; 537 538 if (params->cpus) { 539 retval = osnoise_set_cpus(tool->context, params->cpus); 540 if (retval) { 541 err_msg("Failed to apply CPUs config\n"); 542 goto out_err; 543 } 544 } 545 546 if (params->runtime || params->period) { 547 retval = osnoise_set_runtime_period(tool->context, 548 params->runtime, 549 params->period); 550 if (retval) { 551 err_msg("Failed to set runtime and/or period\n"); 552 goto out_err; 553 } 554 } 555 556 if (params->stop_us) { 557 retval = osnoise_set_stop_us(tool->context, params->stop_us); 558 if (retval) { 559 err_msg("Failed to set stop us\n"); 560 goto out_err; 561 } 562 } 563 564 if (params->stop_total_us) { 565 retval = osnoise_set_stop_total_us(tool->context, params->stop_total_us); 566 if (retval) { 567 err_msg("Failed to set stop total us\n"); 568 goto out_err; 569 } 570 } 571 572 if (params->threshold) { 573 retval = osnoise_set_tracing_thresh(tool->context, params->threshold); 574 if (retval) { 575 err_msg("Failed to set tracing_thresh\n"); 576 goto out_err; 577 } 578 } 579 580 if (params->mode == MODE_HWNOISE) { 581 retval = osnoise_set_irq_disable(tool->context, 1); 582 if (retval) { 583 err_msg("Failed to set OSNOISE_IRQ_DISABLE option\n"); 584 goto out_err; 585 } 586 } 587 588 if (params->hk_cpus) { 589 retval = sched_setaffinity(getpid(), sizeof(params->hk_cpu_set), 590 ¶ms->hk_cpu_set); 591 if (retval == -1) { 592 err_msg("Failed to set rtla to the house keeping CPUs\n"); 593 goto out_err; 594 } 595 } else if (params->cpus) { 596 /* 597 * Even if the user do not set a house-keeping CPU, try to 598 * move rtla to a CPU set different to the one where the user 599 * set the workload to run. 600 * 601 * No need to check results as this is an automatic attempt. 602 */ 603 auto_house_keeping(¶ms->monitored_cpus); 604 } 605 606 return 0; 607 608out_err: 609 return -1; 610} 611 612/* 613 * osnoise_init_top - initialize a osnoise top tool with parameters 614 */ 615struct osnoise_tool *osnoise_init_top(struct osnoise_top_params *params) 616{ 617 struct osnoise_tool *tool; 618 int nr_cpus; 619 620 nr_cpus = sysconf(_SC_NPROCESSORS_CONF); 621 622 tool = osnoise_init_tool("osnoise_top"); 623 if (!tool) 624 return NULL; 625 626 tool->data = osnoise_alloc_top(nr_cpus); 627 if (!tool->data) 628 goto out_err; 629 630 tool->params = params; 631 632 tep_register_event_handler(tool->trace.tep, -1, "ftrace", "osnoise", 633 osnoise_top_handler, NULL); 634 635 return tool; 636 637out_err: 638 osnoise_free_top(tool->data); 639 osnoise_destroy_tool(tool); 640 return NULL; 641} 642 643static int stop_tracing; 644static void stop_top(int sig) 645{ 646 stop_tracing = 1; 647} 648 649/* 650 * osnoise_top_set_signals - handles the signal to stop the tool 651 */ 652static void osnoise_top_set_signals(struct osnoise_top_params *params) 653{ 654 signal(SIGINT, stop_top); 655 if (params->duration) { 656 signal(SIGALRM, stop_top); 657 alarm(params->duration); 658 } 659} 660 661int osnoise_top_main(int argc, char **argv) 662{ 663 struct osnoise_top_params *params; 664 struct osnoise_tool *record = NULL; 665 struct osnoise_tool *tool = NULL; 666 struct trace_instance *trace; 667 int return_value = 1; 668 int retval; 669 670 params = osnoise_top_parse_args(argc, argv); 671 if (!params) 672 exit(1); 673 674 tool = osnoise_init_top(params); 675 if (!tool) { 676 err_msg("Could not init osnoise top\n"); 677 goto out_exit; 678 } 679 680 retval = osnoise_top_apply_config(tool, params); 681 if (retval) { 682 err_msg("Could not apply config\n"); 683 goto out_free; 684 } 685 686 trace = &tool->trace; 687 688 retval = enable_osnoise(trace); 689 if (retval) { 690 err_msg("Failed to enable osnoise tracer\n"); 691 goto out_free; 692 } 693 694 if (params->set_sched) { 695 retval = set_comm_sched_attr("osnoise/", ¶ms->sched_param); 696 if (retval) { 697 err_msg("Failed to set sched parameters\n"); 698 goto out_free; 699 } 700 } 701 702 if (params->cgroup) { 703 retval = set_comm_cgroup("osnoise/", params->cgroup_name); 704 if (!retval) { 705 err_msg("Failed to move threads to cgroup\n"); 706 goto out_free; 707 } 708 } 709 710 if (params->trace_output) { 711 record = osnoise_init_trace_tool("osnoise"); 712 if (!record) { 713 err_msg("Failed to enable the trace instance\n"); 714 goto out_free; 715 } 716 717 if (params->events) { 718 retval = trace_events_enable(&record->trace, params->events); 719 if (retval) 720 goto out_top; 721 } 722 } 723 724 /* 725 * Start the tracer here, after having set all instances. 726 * 727 * Let the trace instance start first for the case of hitting a stop 728 * tracing while enabling other instances. The trace instance is the 729 * one with most valuable information. 730 */ 731 if (params->trace_output) 732 trace_instance_start(&record->trace); 733 trace_instance_start(trace); 734 735 tool->start_time = time(NULL); 736 osnoise_top_set_signals(params); 737 738 while (!stop_tracing) { 739 sleep(params->sleep_time); 740 741 retval = tracefs_iterate_raw_events(trace->tep, 742 trace->inst, 743 NULL, 744 0, 745 collect_registered_events, 746 trace); 747 if (retval < 0) { 748 err_msg("Error iterating on events\n"); 749 goto out_top; 750 } 751 752 if (!params->quiet) 753 osnoise_print_stats(params, tool); 754 755 if (trace_is_off(&tool->trace, &record->trace)) 756 break; 757 758 } 759 760 osnoise_print_stats(params, tool); 761 762 return_value = 0; 763 764 if (trace_is_off(&tool->trace, &record->trace)) { 765 printf("osnoise hit stop tracing\n"); 766 if (params->trace_output) { 767 printf(" Saving trace to %s\n", params->trace_output); 768 save_trace_to_file(record->trace.inst, params->trace_output); 769 } 770 } 771 772out_top: 773 trace_events_destroy(&record->trace, params->events); 774 params->events = NULL; 775out_free: 776 osnoise_free_top(tool->data); 777 osnoise_destroy_tool(record); 778 osnoise_destroy_tool(tool); 779 free(params); 780out_exit: 781 exit(return_value); 782} 783