tools/perf/builtin-top.c

   1 /*
   2  * builtin-top.c
   3  *
   4  * Builtin top command: Display a continuously updated profile of
   5  * any workload, CPU or specific PID.
   6  *
   7  * Copyright (C) 2008, Red Hat Inc, Ingo Molnar <mingo@redhat.com>
   8  *
   9  * Improvements and fixes by:
  10  *
  11  *   Arjan van de Ven <arjan@linux.intel.com>
  12  *   Yanmin Zhang <yanmin.zhang@intel.com>
  13  *   Wu Fengguang <fengguang.wu@intel.com>
  14  *   Mike Galbraith <efault@gmx.de>
  15  *   Paul Mackerras <paulus@samba.org>
  16  *
  17  * Released under the GPL v2. (and only v2, not any later version)
  18  */
  19 #include "builtin.h"
  20
  21 #include "perf.h"
  22
  23 #include "util/symbol.h"
  24 #include "util/color.h"
  25 #include "util/util.h"
  26 #include "util/rbtree.h"
  27 #include "util/parse-options.h"
  28 #include "util/parse-events.h"
  29
  30 #include <assert.h>
  31 #include <fcntl.h>
  32
  33 #include <stdio.h>
  34
  35 #include <errno.h>
  36 #include <time.h>
  37 #include <sched.h>
  38 #include <pthread.h>
  39
  40 #include <sys/syscall.h>
  41 #include <sys/ioctl.h>
  42 #include <sys/poll.h>
  43 #include <sys/prctl.h>
  44 #include <sys/wait.h>
  45 #include <sys/uio.h>
  46 #include <sys/mman.h>
  47
  48 #include <linux/unistd.h>
  49 #include <linux/types.h>
  50
  51 static int                      fd[MAX_NR_CPUS][MAX_COUNTERS];
  52
  53 static int                      system_wide                     =  0;
  54
  55 static int                      default_interval                = 100000;
  56
  57 static u64                      count_filter                    =  5;
  58 static int                      print_entries                   = 15;
  59
  60 static int                      target_pid                      = -1;
  61 static int                      profile_cpu                     = -1;
  62 static int                      nr_cpus                         =  0;
  63 static unsigned int             realtime_prio                   =  0;
  64 static int                      group                           =  0;
  65 static unsigned int             page_size;
  66 static unsigned int             mmap_pages                      = 16;
  67 static int                      freq                            =  0;
  68 static int                      verbose                         =  0;
  69
  70 static char                     *sym_filter;
  71 static unsigned long            filter_start;
  72 static unsigned long            filter_end;
  73
  74 static int                      delay_secs                      =  2;
  75 static int                      zero;
  76 static int                      dump_symtab;
  77
  78 /*
  79  * Symbols
  80  */
  81
  82 static u64                      min_ip;
  83 static u64                      max_ip = -1ll;
  84
  85 struct sym_entry {
  86         struct rb_node          rb_node;
  87         struct list_head        node;
  88         unsigned long           count[MAX_COUNTERS];
  89         unsigned long           snap_count;
  90         double                  weight;
  91         int                     skip;
  92 };
  93
  94 struct sym_entry                *sym_filter_entry;
  95
  96 struct dso                      *kernel_dso;
  97
  98 /*
  99  * Symbols will be added here in record_ip and will get out
 100  * after decayed.
 101  */
 102 static LIST_HEAD(active_symbols);
 103 static pthread_mutex_t active_symbols_lock = PTHREAD_MUTEX_INITIALIZER;
 104
 105 /*
 106  * Ordering weight: count-1 * count-2 * ... / count-n
 107  */
 108 static double sym_weight(const struct sym_entry *sym)
 109 {
 110         double weight = sym->snap_count;
 111         int counter;
 112
 113         for (counter = 1; counter < nr_counters-1; counter++)
 114                 weight *= sym->count[counter];
 115
 116         weight /= (sym->count[counter] + 1);
 117
 118         return weight;
 119 }
 120
 121 static long                     samples;
 122 static long                     userspace_samples;
 123 static const char               CONSOLE_CLEAR[] = "\e[H\e[2J";
 124
 125 static void __list_insert_active_sym(struct sym_entry *syme)
 126 {
 127         list_add(&syme->node, &active_symbols);
 128 }
 129
 130 static void list_remove_active_sym(struct sym_entry *syme)
 131 {
 132         pthread_mutex_lock(&active_symbols_lock);
 133         list_del_init(&syme->node);
 134         pthread_mutex_unlock(&active_symbols_lock);
 135 }
 136
 137 static void rb_insert_active_sym(struct rb_root *tree, struct sym_entry *se)
 138 {
 139         struct rb_node **p = &tree->rb_node;
 140         struct rb_node *parent = NULL;
 141         struct sym_entry *iter;
 142
 143         while (*p != NULL) {
 144                 parent = *p;
 145                 iter = rb_entry(parent, struct sym_entry, rb_node);
 146
 147                 if (se->weight > iter->weight)
 148                         p = &(*p)->rb_left;
 149                 else
 150                         p = &(*p)->rb_right;
 151         }
 152
 153         rb_link_node(&se->rb_node, parent, p);
 154         rb_insert_color(&se->rb_node, tree);
 155 }
 156
 157 static void print_sym_table(void)
 158 {
 159         int printed = 0, j;
 160         int counter;
 161         float samples_per_sec = samples/delay_secs;
 162         float ksamples_per_sec = (samples-userspace_samples)/delay_secs;
 163         float sum_ksamples = 0.0;
 164         struct sym_entry *syme, *n;
 165         struct rb_root tmp = RB_ROOT;
 166         struct rb_node *nd;
 167
 168         samples = userspace_samples = 0;
 169
 170         /* Sort the active symbols */
 171         pthread_mutex_lock(&active_symbols_lock);
 172         syme = list_entry(active_symbols.next, struct sym_entry, node);
 173         pthread_mutex_unlock(&active_symbols_lock);
 174
 175         list_for_each_entry_safe_from(syme, n, &active_symbols, node) {
 176                 syme->snap_count = syme->count[0];
 177                 if (syme->snap_count != 0) {
 178                         syme->weight = sym_weight(syme);
 179                         rb_insert_active_sym(&tmp, syme);
 180                         sum_ksamples += syme->snap_count;
 181
 182                         for (j = 0; j < nr_counters; j++)
 183                                 syme->count[j] = zero ? 0 : syme->count[j] * 7 / 8;
 184                 } else
 185                         list_remove_active_sym(syme);
 186         }
 187
 188         puts(CONSOLE_CLEAR);
 189
 190         printf(
 191 "------------------------------------------------------------------------------\n");
 192         printf( "   PerfTop:%8.0f irqs/sec  kernel:%4.1f%% [",
 193                 samples_per_sec,
 194                 100.0 - (100.0*((samples_per_sec-ksamples_per_sec)/samples_per_sec)));
 195
 196         if (nr_counters == 1) {
 197                 printf("%Ld", (u64)attrs[0].sample_period);
 198                 if (freq)
 199                         printf("Hz ");
 200                 else
 201                         printf(" ");
 202         }
 203
 204         for (counter = 0; counter < nr_counters; counter++) {
 205                 if (counter)
 206                         printf("/");
 207
 208                 printf("%s", event_name(counter));
 209         }
 210
 211         printf( "], ");
 212
 213         if (target_pid != -1)
 214                 printf(" (target_pid: %d", target_pid);
 215         else
 216                 printf(" (all");
 217
 218         if (profile_cpu != -1)
 219                 printf(", cpu: %d)\n", profile_cpu);
 220         else {
 221                 if (target_pid != -1)
 222                         printf(")\n");
 223                 else
 224                         printf(", %d CPUs)\n", nr_cpus);
 225         }
 226
 227         printf("------------------------------------------------------------------------------\n\n");
 228
 229         if (nr_counters == 1)
 230                 printf("             samples    pcnt");
 231         else
 232                 printf("  weight     samples    pcnt");
 233
 234         printf("         RIP          kernel function\n"
 235                        "  ______     _______   _____   ________________   _______________\n\n"
 236         );
 237
 238         for (nd = rb_first(&tmp); nd; nd = rb_next(nd)) {
 239                 struct sym_entry *syme = rb_entry(nd, struct sym_entry, rb_node);
 240                 struct symbol *sym = (struct symbol *)(syme + 1);
 241                 char *color = PERF_COLOR_NORMAL;
 242                 double pcnt;
 243
 244                 if (++printed > print_entries || syme->snap_count < count_filter)
 245                         continue;
 246
 247                 pcnt = 100.0 - (100.0 * ((sum_ksamples - syme->snap_count) /
 248                                          sum_ksamples));
 249
 250                 /*
 251                  * We color high-overhead entries in red, mid-overhead
 252                  * entries in green - and keep the low overhead places
 253                  * normal:
 254                  */
 255                 if (pcnt >= 5.0) {
 256                         color = PERF_COLOR_RED;
 257                 } else {
 258                         if (pcnt >= 0.5)
 259                                 color = PERF_COLOR_GREEN;
 260                 }
 261
 262                 if (nr_counters == 1)
 263                         printf("%20.2f - ", syme->weight);
 264                 else
 265                         printf("%9.1f %10ld - ", syme->weight, syme->snap_count);
 266
 267                 color_fprintf(stdout, color, "%4.1f%%", pcnt);
 268                 printf(" - %016llx : %s\n", sym->start, sym->name);
 269         }
 270 }
 271
 272 static void *display_thread(void *arg)
 273 {
 274         struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };
 275         int delay_msecs = delay_secs * 1000;
 276
 277         printf("PerfTop refresh period: %d seconds\n", delay_secs);
 278
 279         do {
 280                 print_sym_table();
 281         } while (!poll(&stdin_poll, 1, delay_msecs) == 1);
 282
 283         printf("key pressed - exiting.\n");
 284         exit(0);
 285
 286         return NULL;
 287 }
 288
 289 static int symbol_filter(struct dso *self, struct symbol *sym)
 290 {
 291         static int filter_match;
 292         struct sym_entry *syme;
 293         const char *name = sym->name;
 294
 295         if (!strcmp(name, "_text") ||
 296             !strcmp(name, "_etext") ||
 297             !strcmp(name, "_sinittext") ||
 298             !strncmp("init_module", name, 11) ||
 299             !strncmp("cleanup_module", name, 14) ||
 300             strstr(name, "_text_start") ||
 301             strstr(name, "_text_end"))
 302                 return 1;
 303
 304         syme = dso__sym_priv(self, sym);
 305         /* Tag samples to be skipped. */
 306         if (!strcmp("default_idle", name) ||
 307             !strcmp("cpu_idle", name) ||
 308             !strcmp("enter_idle", name) ||
 309             !strcmp("exit_idle", name) ||
 310             !strcmp("mwait_idle", name))
 311                 syme->skip = 1;
 312
 313         if (filter_match == 1) {
 314                 filter_end = sym->start;
 315                 filter_match = -1;
 316                 if (filter_end - filter_start > 10000) {
 317                         fprintf(stderr,
 318                                 "hm, too large filter symbol <%s> - skipping.\n",
 319                                 sym_filter);
 320                         fprintf(stderr, "symbol filter start: %016lx\n",
 321                                 filter_start);
 322                         fprintf(stderr, "                end: %016lx\n",
 323                                 filter_end);
 324                         filter_end = filter_start = 0;
 325                         sym_filter = NULL;
 326                         sleep(1);
 327                 }
 328         }
 329
 330         if (filter_match == 0 && sym_filter && !strcmp(name, sym_filter)) {
 331                 filter_match = 1;
 332                 filter_start = sym->start;
 333         }
 334
 335
 336         return 0;
 337 }
 338
 339 static int parse_symbols(void)
 340 {
 341         struct rb_node *node;
 342         struct symbol  *sym;
 343
 344         kernel_dso = dso__new("[kernel]", sizeof(struct sym_entry));
 345         if (kernel_dso == NULL)
 346                 return -1;
 347
 348         if (dso__load_kernel(kernel_dso, NULL, symbol_filter, 1) != 0)
 349                 goto out_delete_dso;
 350
 351         node = rb_first(&kernel_dso->syms);
 352         sym = rb_entry(node, struct symbol, rb_node);
 353         min_ip = sym->start;
 354
 355         node = rb_last(&kernel_dso->syms);
 356         sym = rb_entry(node, struct symbol, rb_node);
 357         max_ip = sym->end;
 358
 359         if (dump_symtab)
 360                 dso__fprintf(kernel_dso, stderr);
 361
 362         return 0;
 363
 364 out_delete_dso:
 365         dso__delete(kernel_dso);
 366         kernel_dso = NULL;
 367         return -1;
 368 }
 369
 370 #define TRACE_COUNT     3
 371
 372 /*
 373  * Binary search in the histogram table and record the hit:
 374  */
 375 static void record_ip(u64 ip, int counter)
 376 {
 377         struct symbol *sym = dso__find_symbol(kernel_dso, ip);
 378
 379         if (sym != NULL) {
 380                 struct sym_entry *syme = dso__sym_priv(kernel_dso, sym);
 381
 382                 if (!syme->skip) {
 383                         syme->count[counter]++;
 384                         pthread_mutex_lock(&active_symbols_lock);
 385                         if (list_empty(&syme->node) || !syme->node.next)
 386                                 __list_insert_active_sym(syme);
 387                         pthread_mutex_unlock(&active_symbols_lock);
 388                         return;
 389                 }
 390         }
 391
 392         samples--;
 393 }
 394
 395 static void process_event(u64 ip, int counter)
 396 {
 397         samples++;
 398
 399         if (ip < min_ip || ip > max_ip) {
 400                 userspace_samples++;
 401                 return;
 402         }
 403
 404         record_ip(ip, counter);
 405 }
 406
 407 struct mmap_data {
 408         int                     counter;
 409         void                    *base;
 410         unsigned int            mask;
 411         unsigned int            prev;
 412 };
 413
 414 static unsigned int mmap_read_head(struct mmap_data *md)
 415 {
 416         struct perf_counter_mmap_page *pc = md->base;
 417         int head;
 418
 419         head = pc->data_head;
 420         rmb();
 421
 422         return head;
 423 }
 424
 425 struct timeval last_read, this_read;
 426
 427 static void mmap_read_counter(struct mmap_data *md)
 428 {
 429         unsigned int head = mmap_read_head(md);
 430         unsigned int old = md->prev;
 431         unsigned char *data = md->base + page_size;
 432         int diff;
 433
 434         gettimeofday(&this_read, NULL);
 435
 436         /*
 437          * If we're further behind than half the buffer, there's a chance
 438          * the writer will bite our tail and mess up the samples under us.
 439          *
 440          * If we somehow ended up ahead of the head, we got messed up.
 441          *
 442          * In either case, truncate and restart at head.
 443          */
 444         diff = head - old;
 445         if (diff > md->mask / 2 || diff < 0) {
 446                 struct timeval iv;
 447                 unsigned long msecs;
 448
 449                 timersub(&this_read, &last_read, &iv);
 450                 msecs = iv.tv_sec*1000 + iv.tv_usec/1000;
 451
 452                 fprintf(stderr, "WARNING: failed to keep up with mmap data."
 453                                 "  Last read %lu msecs ago.\n", msecs);
 454
 455                 /*
 456                  * head points to a known good entry, start there.
 457                  */
 458                 old = head;
 459         }
 460
 461         last_read = this_read;
 462
 463         for (; old != head;) {
 464                 struct ip_event {
 465                         struct perf_event_header header;
 466                         u64 ip;
 467                         u32 pid, target_pid;
 468                 };
 469                 struct mmap_event {
 470                         struct perf_event_header header;
 471                         u32 pid, target_pid;
 472                         u64 start;
 473                         u64 len;
 474                         u64 pgoff;
 475                         char filename[PATH_MAX];
 476                 };
 477
 478                 typedef union event_union {
 479                         struct perf_event_header header;
 480                         struct ip_event ip;
 481                         struct mmap_event mmap;
 482                 } event_t;
 483
 484                 event_t *event = (event_t *)&data[old & md->mask];
 485
 486                 event_t event_copy;
 487
 488                 size_t size = event->header.size;
 489
 490                 /*
 491                  * Event straddles the mmap boundary -- header should always
 492                  * be inside due to u64 alignment of output.
 493                  */
 494                 if ((old & md->mask) + size != ((old + size) & md->mask)) {
 495                         unsigned int offset = old;
 496                         unsigned int len = min(sizeof(*event), size), cpy;
 497                         void *dst = &event_copy;
 498
 499                         do {
 500                                 cpy = min(md->mask + 1 - (offset & md->mask), len);
 501                                 memcpy(dst, &data[offset & md->mask], cpy);
 502                                 offset += cpy;
 503                                 dst += cpy;
 504                                 len -= cpy;
 505                         } while (len);
 506
 507                         event = &event_copy;
 508                 }
 509
 510                 old += size;
 511
 512                 if (event->header.misc & PERF_EVENT_MISC_OVERFLOW) {
 513                         if (event->header.type & PERF_SAMPLE_IP)
 514                                 process_event(event->ip.ip, md->counter);
 515                 }
 516         }
 517
 518         md->prev = old;
 519 }
 520
 521 static struct pollfd event_array[MAX_NR_CPUS * MAX_COUNTERS];
 522 static struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS];
 523
 524 static void mmap_read(void)
 525 {
 526         int i, counter;
 527
 528         for (i = 0; i < nr_cpus; i++) {
 529                 for (counter = 0; counter < nr_counters; counter++)
 530                         mmap_read_counter(&mmap_array[i][counter]);
 531         }
 532 }
 533
 534 int nr_poll;
 535 int group_fd;
 536
 537 static void start_counter(int i, int counter)
 538 {
 539         struct perf_counter_attr *attr;
 540         unsigned int cpu;
 541
 542         cpu = profile_cpu;
 543         if (target_pid == -1 && profile_cpu == -1)
 544                 cpu = i;
 545
 546         attr = attrs + counter;
 547
 548         attr->sample_type       = PERF_SAMPLE_IP | PERF_SAMPLE_TID;
 549         attr->freq              = freq;
 550
 551 try_again:
 552         fd[i][counter] = sys_perf_counter_open(attr, target_pid, cpu, group_fd, 0);
 553
 554         if (fd[i][counter] < 0) {
 555                 int err = errno;
 556
 557                 if (err == EPERM)
 558                         die("No permission - are you root?\n");
 559                 /*
 560                  * If it's cycles then fall back to hrtimer
 561                  * based cpu-clock-tick sw counter, which
 562                  * is always available even if no PMU support:
 563                  */
 564                 if (attr->type == PERF_TYPE_HARDWARE
 565                         && attr->config == PERF_COUNT_HW_CPU_CYCLES) {
 566
 567                         if (verbose)
 568                                 warning(" ... trying to fall back to cpu-clock-ticks\n");
 569
 570                         attr->type = PERF_TYPE_SOFTWARE;
 571                         attr->config = PERF_COUNT_SW_CPU_CLOCK;
 572                         goto try_again;
 573                 }
 574                 printf("\n");
 575                 error("perfcounter syscall returned with %d (%s)\n",
 576                         fd[i][counter], strerror(err));
 577                 die("No CONFIG_PERF_COUNTERS=y kernel support configured?\n");
 578                 exit(-1);
 579         }
 580         assert(fd[i][counter] >= 0);
 581         fcntl(fd[i][counter], F_SETFL, O_NONBLOCK);
 582
 583         /*
 584          * First counter acts as the group leader:
 585          */
 586         if (group && group_fd == -1)
 587                 group_fd = fd[i][counter];
 588
 589         event_array[nr_poll].fd = fd[i][counter];
 590         event_array[nr_poll].events = POLLIN;
 591         nr_poll++;
 592
 593         mmap_array[i][counter].counter = counter;
 594         mmap_array[i][counter].prev = 0;
 595         mmap_array[i][counter].mask = mmap_pages*page_size - 1;
 596         mmap_array[i][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
 597                         PROT_READ, MAP_SHARED, fd[i][counter], 0);
 598         if (mmap_array[i][counter].base == MAP_FAILED)
 599                 die("failed to mmap with %d (%s)\n", errno, strerror(errno));
 600 }
 601
 602 static int __cmd_top(void)
 603 {
 604         pthread_t thread;
 605         int i, counter;
 606         int ret;
 607
 608         for (i = 0; i < nr_cpus; i++) {
 609                 group_fd = -1;
 610                 for (counter = 0; counter < nr_counters; counter++)
 611                         start_counter(i, counter);
 612         }
 613
 614         /* Wait for a minimal set of events before starting the snapshot */
 615         poll(event_array, nr_poll, 100);
 616
 617         mmap_read();
 618
 619         if (pthread_create(&thread, NULL, display_thread, NULL)) {
 620                 printf("Could not create display thread.\n");
 621                 exit(-1);
 622         }
 623
 624         if (realtime_prio) {
 625                 struct sched_param param;
 626
 627                 param.sched_priority = realtime_prio;
 628                 if (sched_setscheduler(0, SCHED_FIFO, &param)) {
 629                         printf("Could not set realtime priority.\n");
 630                         exit(-1);
 631                 }
 632         }
 633
 634         while (1) {
 635                 int hits = samples;
 636
 637                 mmap_read();
 638
 639                 if (hits == samples)
 640                         ret = poll(event_array, nr_poll, 100);
 641         }
 642
 643         return 0;
 644 }
 645
 646 static const char * const top_usage[] = {
 647         "perf top [<options>]",
 648         NULL
 649 };
 650
 651 static const struct option options[] = {
 652         OPT_CALLBACK('e', "event", NULL, "event",
 653                      "event selector. use 'perf list' to list available events",
 654                      parse_events),
 655         OPT_INTEGER('c', "count", &default_interval,
 656                     "event period to sample"),
 657         OPT_INTEGER('p', "pid", &target_pid,
 658                     "profile events on existing pid"),
 659         OPT_BOOLEAN('a', "all-cpus", &system_wide,
 660                             "system-wide collection from all CPUs"),
 661         OPT_INTEGER('C', "CPU", &profile_cpu,
 662                     "CPU to profile on"),
 663         OPT_INTEGER('m', "mmap-pages", &mmap_pages,
 664                     "number of mmap data pages"),
 665         OPT_INTEGER('r', "realtime", &realtime_prio,
 666                     "collect data with this RT SCHED_FIFO priority"),
 667         OPT_INTEGER('d', "delay", &delay_secs,
 668                     "number of seconds to delay between refreshes"),
 669         OPT_BOOLEAN('D', "dump-symtab", &dump_symtab,
 670                             "dump the symbol table used for profiling"),
 671         OPT_INTEGER('f', "count-filter", &count_filter,
 672                     "only display functions with more events than this"),
 673         OPT_BOOLEAN('g', "group", &group,
 674                             "put the counters into a counter group"),
 675         OPT_STRING('s', "sym-filter", &sym_filter, "pattern",
 676                     "only display symbols matchig this pattern"),
 677         OPT_BOOLEAN('z', "zero", &group,
 678                     "zero history across updates"),
 679         OPT_INTEGER('F', "freq", &freq,
 680                     "profile at this frequency"),
 681         OPT_INTEGER('E', "entries", &print_entries,
 682                     "display this many functions"),
 683         OPT_BOOLEAN('v', "verbose", &verbose,
 684                     "be more verbose (show counter open errors, etc)"),
 685         OPT_END()
 686 };
 687
 688 int cmd_top(int argc, const char **argv, const char *prefix)
 689 {
 690         int counter;
 691
 692         page_size = sysconf(_SC_PAGE_SIZE);
 693
 694         argc = parse_options(argc, argv, options, top_usage, 0);
 695         if (argc)
 696                 usage_with_options(top_usage, options);
 697
 698         if (freq) {
 699                 default_interval = freq;
 700                 freq = 1;
 701         }
 702
 703         /* CPU and PID are mutually exclusive */
 704         if (target_pid != -1 && profile_cpu != -1) {
 705                 printf("WARNING: PID switch overriding CPU\n");
 706                 sleep(1);
 707                 profile_cpu = -1;
 708         }
 709
 710         if (!nr_counters)
 711                 nr_counters = 1;
 712
 713         if (delay_secs < 1)
 714                 delay_secs = 1;
 715
 716         parse_symbols();
 717
 718         /*
 719          * Fill in the ones not specifically initialized via -c:
 720          */
 721         for (counter = 0; counter < nr_counters; counter++) {
 722                 if (attrs[counter].sample_period)
 723                         continue;
 724
 725                 attrs[counter].sample_period = default_interval;
 726         }
 727
 728         nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
 729         assert(nr_cpus <= MAX_NR_CPUS);
 730         assert(nr_cpus >= 0);
 731
 732         if (target_pid != -1 || profile_cpu != -1)
 733                 nr_cpus = 1;
 734
 735         return __cmd_top();
 736 }