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