src/runtime/cheneygc.c

   1 /*
   2  * stop and copy GC based on Cheney's algorithm
   3  */
   4
   5 /*
   6  * This software is part of the SBCL system. See the README file for
   7  * more information.
   8  *
   9  * This software is derived from the CMU CL system, which was
  10  * written at Carnegie Mellon University and released into the
  11  * public domain. The software is in the public domain and is
  12  * provided with absolutely no warranty. See the COPYING and CREDITS
  13  * files for more information.
  14  */
  15
  16 #include <stdio.h>
  17 #include <sys/time.h>
  18 #include <sys/resource.h>
  19 #include <signal.h>
  20 #include "sbcl.h"
  21 #include "runtime.h"
  22 #include "os.h"
  23 #include "gc.h"
  24 #include "gc-internal.h"
  25 #include "globals.h"
  26 #include "interrupt.h"
  27 #include "validate.h"
  28 #include "lispregs.h"
  29 #include "interr.h"
  30 #include "genesis/static-symbols.h"
  31 #include "genesis/primitive-objects.h"
  32 #include "thread.h"
  33
  34 /* So you need to debug? */
  35 #if 0
  36 #define PRINTNOISE
  37 #define DEBUG_SPACE_PREDICATES
  38 #define DEBUG_SCAVENGE_VERBOSE
  39 #define DEBUG_COPY_VERBOSE
  40 #define DEBUG_CODE_GC
  41 #endif
  42
  43 lispobj *from_space;
  44 lispobj *from_space_free_pointer;
  45
  46 lispobj *new_space;
  47 lispobj *new_space_free_pointer;
  48
  49 static void scavenge_newspace(void);
  50 static void scavenge_interrupt_contexts(void);
  51
  52 extern unsigned long bytes_consed_between_gcs;
  53
  54 \f
  55 /* collecting garbage */
  56
  57 #ifdef PRINTNOISE
  58 static double
  59 tv_diff(struct timeval *x, struct timeval *y)
  60 {
  61     return (((double) x->tv_sec + (double) x->tv_usec * 1.0e-6) -
  62             ((double) y->tv_sec + (double) y->tv_usec * 1.0e-6));
  63 }
  64 #endif
  65
  66 #define BYTES_ZERO_BEFORE_END (1<<12)
  67
  68 /* FIXME do we need this?  Doesn't it duplicate lisp code in
  69  * scrub-control-stack? */
  70
  71 static void
  72 zero_stack(void)
  73 {
  74     lispobj *ptr = current_control_stack_pointer;
  75  search:
  76     do {
  77         if (*ptr)
  78             goto fill;
  79         ptr++;
  80     } while (((unsigned long)ptr) & (BYTES_ZERO_BEFORE_END-1));
  81     return;
  82  fill:
  83     do {
  84         *ptr++ = 0;
  85     } while (((unsigned long)ptr) & (BYTES_ZERO_BEFORE_END-1));
  86
  87     goto search;
  88 }
  89
  90
  91 void *
  92 gc_general_alloc(long bytes, int unboxed_p, int quick_p) {
  93     lispobj *new=new_space_free_pointer;
  94     new_space_free_pointer+=(bytes/N_WORD_BYTES);
  95     return new;
  96 }
  97
  98 lispobj  copy_large_unboxed_object(lispobj object, long nwords) {
  99     return copy_object(object,nwords);
 100 }
 101 lispobj  copy_unboxed_object(lispobj object, long nwords) {
 102     return copy_object(object,nwords);
 103 }
 104 lispobj  copy_large_object(lispobj object, long nwords) {
 105     return copy_object(object,nwords);
 106 }
 107
 108 /* Note: The generic GC interface we're implementing passes us a
 109  * last_generation argument. That's meaningless for us, since we're
 110  * not a generational GC. So we ignore it. */
 111 void
 112 collect_garbage(unsigned ignore)
 113 {
 114 #ifdef PRINTNOISE
 115     struct timeval start_tv, stop_tv;
 116     struct rusage start_rusage, stop_rusage;
 117     double real_time, system_time, user_time;
 118     double percent_retained, gc_rate;
 119     unsigned long size_discarded;
 120 #endif
 121     unsigned long size_retained;
 122     lispobj *current_static_space_free_pointer;
 123     unsigned long static_space_size;
 124     unsigned long control_stack_size, binding_stack_size;
 125     sigset_t tmp, old;
 126     struct thread *th=arch_os_get_current_thread();
 127     struct interrupt_data *data=th->interrupt_data;
 128
 129
 130 #ifdef PRINTNOISE
 131     printf("[Collecting garbage ... \n");
 132
 133     getrusage(RUSAGE_SELF, &start_rusage);
 134     gettimeofday(&start_tv, (struct timezone *) 0);
 135 #endif
 136
 137     /* it's possible that signals are blocked already if this was called
 138      * from a signal handler (e.g. with the sigsegv gc_trigger stuff) */
 139     sigemptyset(&tmp);
 140     sigaddset_blockable(&tmp);
 141     thread_sigmask(SIG_BLOCK, &tmp, &old);
 142
 143     current_static_space_free_pointer =
 144         (lispobj *) ((unsigned long)
 145                      SymbolValue(STATIC_SPACE_FREE_POINTER,0));
 146
 147
 148     /* Set up from space and new space pointers. */
 149
 150     from_space = current_dynamic_space;
 151     from_space_free_pointer = dynamic_space_free_pointer;
 152
 153 #ifdef PRINTNOISE
 154     fprintf(stderr,"from_space = %lx\n",
 155             (unsigned long) current_dynamic_space);
 156 #endif
 157     if (current_dynamic_space == (lispobj *) DYNAMIC_0_SPACE_START)
 158         new_space = (lispobj *)DYNAMIC_1_SPACE_START;
 159     else if (current_dynamic_space == (lispobj *) DYNAMIC_1_SPACE_START)
 160         new_space = (lispobj *) DYNAMIC_0_SPACE_START;
 161     else {
 162         lose("GC lossage.  Current dynamic space is bogus!\n");
 163     }
 164     new_space_free_pointer = new_space;
 165
 166     /* Initialize the weak pointer list. */
 167     weak_pointers = (struct weak_pointer *) NULL;
 168
 169
 170     /* Scavenge all of the roots. */
 171 #ifdef PRINTNOISE
 172     printf("Scavenging interrupt contexts ...\n");
 173 #endif
 174     scavenge_interrupt_contexts();
 175
 176 #ifdef PRINTNOISE
 177     printf("Scavenging interrupt handlers (%d bytes) ...\n",
 178            (int)sizeof(interrupt_handlers));
 179 #endif
 180     scavenge((lispobj *) data->interrupt_handlers,
 181              sizeof(data->interrupt_handlers) / sizeof(lispobj));
 182
 183     /* _size quantities are in units of sizeof(lispobj) - i.e. 4 */
 184     control_stack_size =
 185         current_control_stack_pointer-
 186         (lispobj *)th->control_stack_start;
 187 #ifdef PRINTNOISE
 188     printf("Scavenging the control stack at %p (%ld words) ...\n",
 189            ((lispobj *)th->control_stack_start),
 190            control_stack_size);
 191 #endif
 192     scavenge(((lispobj *)th->control_stack_start), control_stack_size);
 193
 194
 195     binding_stack_size =
 196         current_binding_stack_pointer -
 197         (lispobj *)th->binding_stack_start;
 198 #ifdef PRINTNOISE
 199     printf("Scavenging the binding stack %x - %x (%d words) ...\n",
 200            th->binding_stack_start,current_binding_stack_pointer,
 201            (int)(binding_stack_size));
 202 #endif
 203     scavenge(((lispobj *)th->binding_stack_start), binding_stack_size);
 204
 205     static_space_size =
 206         current_static_space_free_pointer - (lispobj *) STATIC_SPACE_START;
 207 #ifdef PRINTNOISE
 208     printf("Scavenging static space %x - %x (%d words) ...\n",
 209            STATIC_SPACE_START,current_static_space_free_pointer,
 210            (int)(static_space_size));
 211 #endif
 212     scavenge(((lispobj *)STATIC_SPACE_START), static_space_size);
 213
 214     /* Scavenge newspace. */
 215 #ifdef PRINTNOISE
 216     printf("Scavenging new space (%d bytes) ...\n",
 217            (int)((new_space_free_pointer - new_space) * sizeof(lispobj)));
 218 #endif
 219     scavenge_newspace();
 220
 221
 222 #if defined(DEBUG_PRINT_GARBAGE)
 223     print_garbage(from_space, from_space_free_pointer);
 224 #endif
 225
 226     /* Scan the weak pointers. */
 227 #ifdef PRINTNOISE
 228     printf("Scanning weak pointers ...\n");
 229 #endif
 230     scan_weak_pointers();
 231
 232
 233     /* Flip spaces. */
 234 #ifdef PRINTNOISE
 235     printf("Flipping spaces ...\n");
 236 #endif
 237
 238     /* Maybe FIXME: it's possible that we could significantly reduce
 239      * RSS by zeroing the from_space or madvise(MADV_DONTNEED) or
 240      * similar os-dependent tricks here */
 241     os_zero((os_vm_address_t) from_space,
 242             (os_vm_size_t) DYNAMIC_SPACE_SIZE);
 243
 244     current_dynamic_space = new_space;
 245     dynamic_space_free_pointer = new_space_free_pointer;
 246
 247 #ifdef PRINTNOISE
 248     size_discarded = (from_space_free_pointer - from_space) * sizeof(lispobj);
 249 #endif
 250     size_retained = (new_space_free_pointer - new_space) * sizeof(lispobj);
 251
 252     os_flush_icache((os_vm_address_t)new_space, size_retained);
 253
 254     /* Zero stack. */
 255 #ifdef PRINTNOISE
 256     printf("Zeroing empty part of control stack ...\n");
 257 #endif
 258     zero_stack();
 259     set_auto_gc_trigger(size_retained+bytes_consed_between_gcs);
 260     thread_sigmask(SIG_SETMASK, &old, 0);
 261
 262
 263 #ifdef PRINTNOISE
 264     gettimeofday(&stop_tv, (struct timezone *) 0);
 265     getrusage(RUSAGE_SELF, &stop_rusage);
 266
 267     printf("done.]\n");
 268
 269     percent_retained = (((float) size_retained) /
 270                         ((float) size_discarded)) * 100.0;
 271
 272     printf("Total of %ld bytes out of %ld bytes retained (%3.2f%%).\n",
 273            size_retained, size_discarded, percent_retained);
 274
 275     real_time = tv_diff(&stop_tv, &start_tv);
 276     user_time = tv_diff(&stop_rusage.ru_utime, &start_rusage.ru_utime);
 277     system_time = tv_diff(&stop_rusage.ru_stime, &start_rusage.ru_stime);
 278
 279     printf("Statistics: %10.2fs real, %10.2fs user, %10.2fs system.\n",
 280            real_time, user_time, system_time);
 281
 282     gc_rate = ((float) size_retained / (float) (1<<20)) / real_time;
 283
 284     printf("%10.2f M bytes/sec collected.\n", gc_rate);
 285 #endif
 286 }
 287
 288 \f
 289 /* scavenging */
 290
 291 static void
 292 scavenge_newspace(void)
 293 {
 294     lispobj *here, *next;
 295
 296     here = new_space;
 297     while (here < new_space_free_pointer) {
 298         /*      printf("here=%lx, new_space_free_pointer=%lx\n",
 299                 here,new_space_free_pointer); */
 300         next = new_space_free_pointer;
 301         scavenge(here, next - here);
 302         here = next;
 303     }
 304     /* printf("done with newspace\n"); */
 305 }
 306 \f
 307 /* scavenging interrupt contexts */
 308
 309 static int boxed_registers[] = BOXED_REGISTERS;
 310
 311 static void
 312 scavenge_interrupt_context(os_context_t *context)
 313 {
 314     int i;
 315 #ifdef reg_LIP
 316     unsigned long lip;
 317     unsigned long lip_offset;
 318     int lip_register_pair;
 319 #endif
 320     unsigned long pc_code_offset;
 321 #ifdef ARCH_HAS_LINK_REGISTER
 322     unsigned long lr_code_offset;
 323 #endif
 324 #ifdef ARCH_HAS_NPC_REGISTER
 325     unsigned long npc_code_offset;
 326 #endif
 327 #ifdef DEBUG_SCAVENGE_VERBOSE
 328     fprintf(stderr, "Scavenging interrupt context at 0x%x\n",context);
 329 #endif
 330     /* Find the LIP's register pair and calculate its offset */
 331     /* before we scavenge the context. */
 332 #ifdef reg_LIP
 333     lip = *os_context_register_addr(context, reg_LIP);
 334     /* 0x7FFFFFFF on 32-bit platforms;
 335        0x7FFFFFFFFFFFFFFF on 64-bit platforms */
 336     lip_offset = (((unsigned long)1) << (N_WORD_BITS - 1)) - 1;
 337     lip_register_pair = -1;
 338     for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
 339         unsigned long reg;
 340         long offset;
 341         int index;
 342
 343         index = boxed_registers[i];
 344         reg = *os_context_register_addr(context, index);
 345         /* would be using PTR if not for integer length issues */
 346         if ((reg & ~((1L<<N_LOWTAG_BITS)-1)) <= lip) {
 347             offset = lip - reg;
 348             if (offset < lip_offset) {
 349                 lip_offset = offset;
 350                 lip_register_pair = index;
 351             }
 352         }
 353     }
 354 #endif /* reg_LIP */
 355
 356     /* Compute the PC's offset from the start of the CODE */
 357     /* register. */
 358     pc_code_offset =
 359         *os_context_pc_addr(context) -
 360         *os_context_register_addr(context, reg_CODE);
 361 #ifdef ARCH_HAS_NPC_REGISTER
 362     npc_code_offset =
 363         *os_context_npc_addr(context) -
 364         *os_context_register_addr(context, reg_CODE);
 365 #endif
 366 #ifdef ARCH_HAS_LINK_REGISTER
 367     lr_code_offset =
 368         *os_context_lr_addr(context) -
 369         *os_context_register_addr(context, reg_CODE);
 370 #endif
 371
 372     /* Scavenge all boxed registers in the context. */
 373     for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
 374         int index;
 375         lispobj foo;
 376
 377         index = boxed_registers[i];
 378         foo = *os_context_register_addr(context,index);
 379         scavenge((lispobj *) &foo, 1);
 380         *os_context_register_addr(context,index) = foo;
 381
 382         /* this is unlikely to work as intended on bigendian
 383          * 64 bit platforms */
 384
 385         scavenge((lispobj *)
 386                  os_context_register_addr(context, index), 1);
 387     }
 388
 389 #ifdef reg_LIP
 390     /* Fix the LIP */
 391     *os_context_register_addr(context, reg_LIP) =
 392         *os_context_register_addr(context, lip_register_pair) + lip_offset;
 393 #endif /* reg_LIP */
 394
 395     /* Fix the PC if it was in from space */
 396     if (from_space_p(*os_context_pc_addr(context)))
 397         *os_context_pc_addr(context) =
 398             *os_context_register_addr(context, reg_CODE) + pc_code_offset;
 399 #ifdef ARCH_HAS_LINK_REGISTER
 400     /* Fix the LR ditto; important if we're being called from
 401      * an assembly routine that expects to return using blr, otherwise
 402      * harmless */
 403     if (from_space_p(*os_context_lr_addr(context)))
 404         *os_context_lr_addr(context) =
 405             *os_context_register_addr(context, reg_CODE) + lr_code_offset;
 406 #endif
 407
 408 #ifdef ARCH_HAS_NPC_REGISTER
 409     if (from_space_p(*os_context_npc_addr(context)))
 410         *os_context_npc_addr(context) =
 411             *os_context_register_addr(context, reg_CODE) + npc_code_offset;
 412 #endif
 413 }
 414
 415 void scavenge_interrupt_contexts(void)
 416 {
 417     int i, index;
 418     os_context_t *context;
 419
 420     struct thread *th=arch_os_get_current_thread();
 421
 422     index = fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,0));
 423
 424
 425 #ifdef DEBUG_SCAVENGE_VERBOSE
 426     fprintf(stderr, "%d interrupt contexts to scan\n",index);
 427 #endif
 428     for (i = 0; i < index; i++) {
 429         context = th->interrupt_contexts[i];
 430         scavenge_interrupt_context(context);
 431     }
 432 }
 433
 434 \f
 435 /* debugging code */
 436
 437 void
 438 print_garbage(lispobj *from_space, lispobj *from_space_free_pointer)
 439 {
 440     lispobj *start;
 441     int total_words_not_copied;
 442
 443     printf("Scanning from space ...\n");
 444
 445     total_words_not_copied = 0;
 446     start = from_space;
 447     while (start < from_space_free_pointer) {
 448         lispobj object;
 449         int forwardp, type, nwords;
 450         lispobj header;
 451
 452         object = *start;
 453         forwardp = is_lisp_pointer(object) && new_space_p(object);
 454
 455         if (forwardp) {
 456             int tag;
 457             lispobj *pointer;
 458
 459             tag = lowtag_of(object);
 460
 461             switch (tag) {
 462             case LIST_POINTER_LOWTAG:
 463                 nwords = 2;
 464                 break;
 465             case INSTANCE_POINTER_LOWTAG:
 466                 printf("Don't know about instances yet!\n");
 467                 nwords = 1;
 468                 break;
 469             case FUN_POINTER_LOWTAG:
 470                 nwords = 1;
 471                 break;
 472             case OTHER_POINTER_LOWTAG:
 473                 pointer = (lispobj *) native_pointer(object);
 474                 header = *pointer;
 475                 type = widetag_of(header);
 476                 nwords = (sizetab[type])(pointer);
 477                 break;
 478             default: nwords=1;  /* shut yer whinging, gcc */
 479             }
 480         } else {
 481             type = widetag_of(object);
 482             nwords = (sizetab[type])(start);
 483             total_words_not_copied += nwords;
 484             printf("%4d words not copied at 0x%16lx; ",
 485                    nwords, (unsigned long) start);
 486             printf("Header word is 0x%08x\n",
 487                    (unsigned int) object);
 488         }
 489         start += nwords;
 490     }
 491     printf("%d total words not copied.\n", total_words_not_copied);
 492 }
 493
 494 \f
 495 /* vector-like objects */
 496
 497 static long
 498 scav_vector(lispobj *where, lispobj object)
 499 {
 500     if (HeaderValue(object) == subtype_VectorValidHashing) {
 501         *where =
 502             (subtype_VectorMustRehash<<N_WIDETAG_BITS) | SIMPLE_VECTOR_WIDETAG;
 503     }
 504
 505     return 1;
 506 }
 507
 508 \f
 509 /* weak pointers */
 510
 511 #define WEAK_POINTER_NWORDS \
 512         CEILING((sizeof(struct weak_pointer) / sizeof(lispobj)), 2)
 513
 514 static long
 515 scav_weak_pointer(lispobj *where, lispobj object)
 516 {
 517     /* Do not let GC scavenge the value slot of the weak pointer */
 518     /* (that is why it is a weak pointer).  Note:  we could use */
 519     /* the scav_unboxed method here. */
 520
 521     return WEAK_POINTER_NWORDS;
 522 }
 523 \f
 524 lispobj *
 525 search_read_only_space(void *pointer)
 526 {
 527     lispobj* start = (lispobj*)READ_ONLY_SPACE_START;
 528     lispobj* end = (lispobj*)SymbolValue(READ_ONLY_SPACE_FREE_POINTER,0);
 529     if ((pointer < (void *)start) || (pointer >= (void *)end))
 530         return NULL;
 531     return (gc_search_space(start,
 532                             (((lispobj *)pointer)+2)-start,
 533                             (lispobj *)pointer));
 534 }
 535
 536 lispobj *
 537 search_static_space(void *pointer)
 538 {
 539     lispobj* start = (lispobj*)STATIC_SPACE_START;
 540     lispobj* end = (lispobj*)SymbolValue(STATIC_SPACE_FREE_POINTER,0);
 541     if ((pointer < (void *)start) || (pointer >= (void *)end))
 542         return NULL;
 543     return (gc_search_space(start,
 544                             (((lispobj *)pointer)+2)-start,
 545                             (lispobj *)pointer));
 546 }
 547
 548 lispobj *
 549 search_dynamic_space(void *pointer)
 550 {
 551     lispobj *start = (lispobj *) current_dynamic_space;
 552     lispobj *end = (lispobj *) dynamic_space_free_pointer;
 553     if ((pointer < (void *)start) || (pointer >= (void *)end))
 554         return NULL;
 555     return (gc_search_space(start,
 556                             (((lispobj *)pointer)+2)-start,
 557                             (lispobj *)pointer));
 558 }
 559 \f
 560 /* initialization.  if gc_init can be moved to after core load, we could
 561  * combine these two functions */
 562
 563 void
 564 gc_init(void)
 565 {
 566     gc_init_tables();
 567     scavtab[SIMPLE_VECTOR_WIDETAG] = scav_vector;
 568     scavtab[WEAK_POINTER_WIDETAG] = scav_weak_pointer;
 569 }
 570
 571 void
 572 gc_initialize_pointers(void)
 573 {
 574     /* FIXME: We do nothing here.  We (briefly) misguidedly attempted
 575        to set current_dynamic_space to DYNAMIC_0_SPACE_START here,
 576        forgetting that (a) actually it could be the other and (b) it's
 577        set in coreparse.c anyway.  There's a FIXME note left here to
 578        note that current_dynamic_space is a violation of OAOO: we can
 579        tell which dynamic space we're currently in by looking at
 580        dynamic_space_free_pointer.  -- CSR, 2002-08-09 */
 581 }
 582
 583
 584
 585 \f
 586 /* noise to manipulate the gc trigger stuff */
 587
 588 /* Functions that substantially change the dynamic space free pointer
 589  * (collect_garbage, purify) are responsible also for resettting the
 590  * auto_gc_trigger */
 591 void set_auto_gc_trigger(os_vm_size_t dynamic_usage)
 592 {
 593     os_vm_address_t addr=(os_vm_address_t)current_dynamic_space
 594         + dynamic_usage;
 595     long length = DYNAMIC_SPACE_SIZE - dynamic_usage;
 596
 597     if (addr < (os_vm_address_t)dynamic_space_free_pointer) {
 598         fprintf(stderr,
 599            "set_auto_gc_trigger: tried to set gc trigger too low! (%ld < 0x%08lx)\n",
 600                 (unsigned long)dynamic_usage,
 601                 (unsigned long)((os_vm_address_t)dynamic_space_free_pointer
 602                                 - (os_vm_address_t)current_dynamic_space));
 603         lose("lost");
 604     }
 605     else if (length < 0) {
 606         fprintf(stderr,
 607                 "set_auto_gc_trigger: tried to set gc trigger too high! (0x%08lx)\n",
 608                 (unsigned long)dynamic_usage);
 609         lose("lost");
 610     }
 611
 612     addr=os_round_up_to_page(addr);
 613     length=os_trunc_size_to_page(length);
 614
 615 #if defined(SUNOS) || defined(SOLARIS)
 616     os_invalidate(addr,length);
 617 #else
 618     os_protect(addr, length, 0);
 619 #endif
 620
 621     current_auto_gc_trigger = (lispobj *)addr;
 622 }
 623
 624 void clear_auto_gc_trigger(void)
 625 {
 626     if (current_auto_gc_trigger!=NULL){
 627 #if defined(SUNOS) || defined(SOLARIS)/* don't want to force whole space into swapping mode... */
 628         os_vm_address_t addr=(os_vm_address_t)current_auto_gc_trigger;
 629         os_vm_size_t length=
 630             DYNAMIC_SPACE_SIZE + (os_vm_address_t)current_dynamic_space - addr;
 631
 632         os_validate(addr,length);
 633 #else
 634         os_protect((os_vm_address_t)current_dynamic_space,
 635                    DYNAMIC_SPACE_SIZE,
 636                    OS_VM_PROT_ALL);
 637 #endif
 638
 639         current_auto_gc_trigger = NULL;
 640     }
 641 }