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 "runtime.h"
  21 #include "sbcl.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 extern struct interrupt_data * global_interrupt_data;
  52
  53 extern unsigned long bytes_consed_between_gcs;
  54
  55 \f
  56 /* collecting garbage */
  57
  58 #ifdef PRINTNOISE
  59 static double
  60 tv_diff(struct timeval *x, struct timeval *y)
  61 {
  62     return (((double) x->tv_sec + (double) x->tv_usec * 1.0e-6) -
  63             ((double) y->tv_sec + (double) y->tv_usec * 1.0e-6));
  64 }
  65 #endif
  66
  67 #define BYTES_ZERO_BEFORE_END (1<<12)
  68
  69 /* FIXME do we need this?  Doesn't it duplicate lisp code in
  70  * scrub-control-stack? */
  71
  72 static void
  73 zero_stack(void)
  74 {
  75     u32 *ptr = (u32 *)current_control_stack_pointer;
  76  search:
  77     do {
  78         if (*ptr)
  79             goto fill;
  80         ptr++;
  81     } while (((unsigned long)ptr) & (BYTES_ZERO_BEFORE_END-1));
  82     return;
  83  fill:
  84     do {
  85         *ptr++ = 0;
  86     } while (((unsigned long)ptr) & (BYTES_ZERO_BEFORE_END-1));
  87
  88     goto search;
  89 }
  90
  91
  92 void *
  93 gc_general_alloc(int bytes, int unboxed_p, int quick_p) {
  94     lispobj *new=new_space_free_pointer;
  95     new_space_free_pointer+=(bytes/4);
  96     return new;
  97 }
  98
  99 lispobj  copy_large_unboxed_object(lispobj object, int nwords) {
 100     return copy_object(object,nwords);
 101 }
 102 lispobj  copy_unboxed_object(lispobj object, int nwords) {
 103     return copy_object(object,nwords);
 104 }
 105 lispobj  copy_large_object(lispobj object, int nwords) {
 106     return copy_object(object,nwords);
 107 }
 108
 109 /* Note: The generic GC interface we're implementing passes us a
 110  * last_generation argument. That's meaningless for us, since we're
 111  * not a generational GC. So we ignore it. */
 112 void
 113 collect_garbage(unsigned ignore)
 114 {
 115 #ifdef PRINTNOISE
 116     struct timeval start_tv, stop_tv;
 117     struct rusage start_rusage, stop_rusage;
 118     double real_time, system_time, user_time;
 119     double percent_retained, gc_rate;
 120     unsigned long size_discarded;
 121 #endif
 122     unsigned long size_retained;
 123     lispobj *current_static_space_free_pointer;
 124     unsigned long static_space_size;
 125     unsigned long control_stack_size, binding_stack_size;
 126     sigset_t tmp, old;
 127     struct thread *th=arch_os_get_current_thread();
 128     struct interrupt_data *data=
 129         th ? th->interrupt_data : global_interrupt_data;
 130
 131
 132 #ifdef PRINTNOISE
 133     printf("[Collecting garbage ... \n");
 134
 135     getrusage(RUSAGE_SELF, &start_rusage);
 136     gettimeofday(&start_tv, (struct timezone *) 0);
 137 #endif
 138
 139     sigemptyset(&tmp);
 140     sigaddset_blockable(&tmp);
 141     sigprocmask(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     os_zero((os_vm_address_t) current_dynamic_space,
 239             (os_vm_size_t) DYNAMIC_SPACE_SIZE);
 240
 241     current_dynamic_space = new_space;
 242     dynamic_space_free_pointer = new_space_free_pointer;
 243
 244 #ifdef PRINTNOISE
 245     size_discarded = (from_space_free_pointer - from_space) * sizeof(lispobj);
 246 #endif
 247     size_retained = (new_space_free_pointer - new_space) * sizeof(lispobj);
 248
 249     /* Zero stack. */
 250 #ifdef PRINTNOISE
 251     printf("Zeroing empty part of control stack ...\n");
 252 #endif
 253     zero_stack();
 254     set_auto_gc_trigger(size_retained+bytes_consed_between_gcs);
 255     sigprocmask(SIG_SETMASK, &old, 0);
 256
 257
 258 #ifdef PRINTNOISE
 259     gettimeofday(&stop_tv, (struct timezone *) 0);
 260     getrusage(RUSAGE_SELF, &stop_rusage);
 261
 262     printf("done.]\n");
 263
 264     percent_retained = (((float) size_retained) /
 265                         ((float) size_discarded)) * 100.0;
 266
 267     printf("Total of %ld bytes out of %ld bytes retained (%3.2f%%).\n",
 268            size_retained, size_discarded, percent_retained);
 269
 270     real_time = tv_diff(&stop_tv, &start_tv);
 271     user_time = tv_diff(&stop_rusage.ru_utime, &start_rusage.ru_utime);
 272     system_time = tv_diff(&stop_rusage.ru_stime, &start_rusage.ru_stime);
 273
 274 #if 0
 275     printf("Statistics:\n");
 276     printf("%10.2f sec of real time\n", real_time);
 277     printf("%10.2f sec of user time,\n", user_time);
 278     printf("%10.2f sec of system time.\n", system_time);
 279 #else
 280     printf("Statistics: %10.2fs real, %10.2fs user, %10.2fs system.\n",
 281            real_time, user_time, system_time);
 282 #endif
 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     /* os_flush_icache((os_vm_address_t) 0, sizeof(unsigned long)); */
 289     /* Maybe FIXME: it's possible that we could significantly reduce
 290      * RSS by zeroing the from_space or madvise(MADV_DONTNEED) or
 291      * similar os-dependent tricks here */
 292 }
 293
 294 \f
 295 /* scavenging */
 296
 297 static void
 298 scavenge_newspace(void)
 299 {
 300     lispobj *here, *next;
 301
 302     here = new_space;
 303     while (here < new_space_free_pointer) {
 304         /*      printf("here=%lx, new_space_free_pointer=%lx\n",
 305                 here,new_space_free_pointer); */
 306         next = new_space_free_pointer;
 307         scavenge(here, next - here);
 308         here = next;
 309     }
 310     /* printf("done with newspace\n"); */
 311 }
 312 \f
 313 /* scavenging interrupt contexts */
 314
 315 static int boxed_registers[] = BOXED_REGISTERS;
 316
 317 static void
 318 scavenge_interrupt_context(os_context_t *context)
 319 {
 320     int i;
 321 #ifdef reg_LIP
 322     unsigned long lip;
 323     unsigned long lip_offset;
 324     int lip_register_pair;
 325 #endif
 326     unsigned long pc_code_offset;
 327 #ifdef ARCH_HAS_LINK_REGISTER
 328     unsigned long lr_code_offset;
 329 #endif
 330 #ifdef ARCH_HAS_NPC_REGISTER
 331     unsigned long npc_code_offset;
 332 #endif
 333 #ifdef DEBUG_SCAVENGE_VERBOSE
 334     fprintf(stderr, "Scavenging interrupt context at 0x%x\n",context);
 335 #endif
 336     /* Find the LIP's register pair and calculate its offset */
 337     /* before we scavenge the context. */
 338 #ifdef reg_LIP
 339     lip = *os_context_register_addr(context, reg_LIP);
 340     /*  0x7FFFFFFF or 0x7FFFFFFFFFFFFFFF ? */
 341     lip_offset = 0x7FFFFFFF;
 342     lip_register_pair = -1;
 343     for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
 344         unsigned long reg;
 345         long offset;
 346         int index;
 347
 348         index = boxed_registers[i];
 349         reg = *os_context_register_addr(context, index);
 350         /* would be using PTR if not for integer length issues */
 351         if ((reg & ~((1L<<N_LOWTAG_BITS)-1)) <= lip) {
 352             offset = lip - reg;
 353             if (offset < lip_offset) {
 354                 lip_offset = offset;
 355                 lip_register_pair = index;
 356             }
 357         }
 358     }
 359 #endif /* reg_LIP */
 360
 361     /* Compute the PC's offset from the start of the CODE */
 362     /* register. */
 363     pc_code_offset =
 364         *os_context_pc_addr(context) -
 365         *os_context_register_addr(context, reg_CODE);
 366 #ifdef ARCH_HAS_NPC_REGISTER
 367     npc_code_offset =
 368         *os_context_npc_addr(context) -
 369         *os_context_register_addr(context, reg_CODE);
 370 #endif
 371 #ifdef ARCH_HAS_LINK_REGISTER
 372     lr_code_offset =
 373         *os_context_lr_addr(context) -
 374         *os_context_register_addr(context, reg_CODE);
 375 #endif
 376
 377     /* Scavenge all boxed registers in the context. */
 378     for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
 379         int index;
 380         lispobj foo;
 381
 382         index = boxed_registers[i];
 383         foo = *os_context_register_addr(context,index);
 384         scavenge((lispobj *) &foo, 1);
 385         *os_context_register_addr(context,index) = foo;
 386
 387         /* this is unlikely to work as intended on bigendian
 388          * 64 bit platforms */
 389
 390         scavenge((lispobj *)
 391                  os_context_register_addr(context, index), 1);
 392     }
 393
 394 #ifdef reg_LIP
 395     /* Fix the LIP */
 396     *os_context_register_addr(context, reg_LIP) =
 397         *os_context_register_addr(context, lip_register_pair) + lip_offset;
 398 #endif /* reg_LIP */
 399
 400     /* Fix the PC if it was in from space */
 401     if (from_space_p(*os_context_pc_addr(context)))
 402         *os_context_pc_addr(context) =
 403             *os_context_register_addr(context, reg_CODE) + pc_code_offset;
 404 #ifdef ARCH_HAS_LINK_REGISTER
 405     /* Fix the LR ditto; important if we're being called from
 406      * an assembly routine that expects to return using blr, otherwise
 407      * harmless */
 408     if (from_space_p(*os_context_lr_addr(context)))
 409         *os_context_lr_addr(context) =
 410             *os_context_register_addr(context, reg_CODE) + lr_code_offset;
 411 #endif
 412
 413 #ifdef ARCH_HAS_NPC_REGISTER
 414     if (from_space_p(*os_context_npc_addr(context)))
 415         *os_context_npc_addr(context) =
 416             *os_context_register_addr(context, reg_CODE) + npc_code_offset;
 417 #endif
 418 }
 419
 420 void scavenge_interrupt_contexts(void)
 421 {
 422     int i, index;
 423     os_context_t *context;
 424
 425     struct thread *th=arch_os_get_current_thread();
 426     struct interrupt_data *data=
 427         th ? th->interrupt_data : global_interrupt_data;
 428
 429     index = fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,0));
 430
 431
 432 #ifdef DEBUG_SCAVENGE_VERBOSE
 433     fprintf(stderr, "%d interrupt contexts to scan\n",index);
 434 #endif
 435     for (i = 0; i < index; i++) {
 436         context = th->interrupt_contexts[i];
 437         scavenge_interrupt_context(context);
 438     }
 439 }
 440
 441 \f
 442 /* debugging code */
 443
 444 void
 445 print_garbage(lispobj *from_space, lispobj *from_space_free_pointer)
 446 {
 447     lispobj *start;
 448     int total_words_not_copied;
 449
 450     printf("Scanning from space ...\n");
 451
 452     total_words_not_copied = 0;
 453     start = from_space;
 454     while (start < from_space_free_pointer) {
 455         lispobj object;
 456         int forwardp, type, nwords;
 457         lispobj header;
 458
 459         object = *start;
 460         forwardp = is_lisp_pointer(object) && new_space_p(object);
 461
 462         if (forwardp) {
 463             int tag;
 464             lispobj *pointer;
 465
 466             tag = lowtag_of(object);
 467
 468             switch (tag) {
 469             case LIST_POINTER_LOWTAG:
 470                 nwords = 2;
 471                 break;
 472             case INSTANCE_POINTER_LOWTAG:
 473                 printf("Don't know about instances yet!\n");
 474                 nwords = 1;
 475                 break;
 476             case FUN_POINTER_LOWTAG:
 477                 nwords = 1;
 478                 break;
 479             case OTHER_POINTER_LOWTAG:
 480                 pointer = (lispobj *) native_pointer(object);
 481                 header = *pointer;
 482                 type = widetag_of(header);
 483                 nwords = (sizetab[type])(pointer);
 484                 break;
 485             default: nwords=1;  /* shut yer whinging, gcc */
 486             }
 487         } else {
 488             type = widetag_of(object);
 489             nwords = (sizetab[type])(start);
 490             total_words_not_copied += nwords;
 491             printf("%4d words not copied at 0x%16lx; ",
 492                    nwords, (unsigned long) start);
 493             printf("Header word is 0x%08x\n",
 494                    (unsigned int) object);
 495         }
 496         start += nwords;
 497     }
 498     printf("%d total words not copied.\n", total_words_not_copied);
 499 }
 500
 501 \f
 502 /* code and code-related objects */
 503
 504 /* FIXME (1) this could probably be defined using something like
 505  *  sizeof(lispobj)*floor(sizeof(struct simple_fun)/sizeof(lispobj))
 506  *    -  FUN_POINTER_LOWTAG
 507  * as I'm reasonably sure that simple_fun->code must always be the
 508  * last slot in the object
 509
 510  * FIXME (2) it also appears in purify.c, and it has a different value
 511  * for SPARC users in that bit
 512  */
 513
 514 #define FUN_RAW_ADDR_OFFSET (6*sizeof(lispobj) - FUN_POINTER_LOWTAG)
 515
 516 /* Note: on the sparc we don't have to do anything special for fdefns, */
 517 /* 'cause the raw-addr has a function lowtag. */
 518 #ifndef LISP_FEATURE_SPARC
 519 static int
 520 scav_fdefn(lispobj *where, lispobj object)
 521 {
 522     struct fdefn *fdefn;
 523
 524     fdefn = (struct fdefn *)where;
 525
 526     if ((char *)(fdefn->fun + FUN_RAW_ADDR_OFFSET)
 527         == (char *)((unsigned long)(fdefn->raw_addr))) {
 528         scavenge(where + 1, sizeof(struct fdefn)/sizeof(lispobj) - 1);
 529         fdefn->raw_addr =
 530             (u32)  ((char *) LOW_WORD(fdefn->fun)) + FUN_RAW_ADDR_OFFSET;
 531         return sizeof(struct fdefn) / sizeof(lispobj);
 532     }
 533     else
 534         return 1;
 535 }
 536 #endif
 537
 538
 539 \f
 540 /* vector-like objects */
 541
 542 /* #define NWORDS(x,y) (CEILING((x),(y)) / (y)) */
 543
 544 static int
 545 scav_vector(lispobj *where, lispobj object)
 546 {
 547     if (HeaderValue(object) == subtype_VectorValidHashing) {
 548         *where =
 549             (subtype_VectorMustRehash<<N_WIDETAG_BITS) | SIMPLE_VECTOR_WIDETAG;
 550     }
 551
 552     return 1;
 553 }
 554
 555 \f
 556 /* weak pointers */
 557
 558 #define WEAK_POINTER_NWORDS \
 559         CEILING((sizeof(struct weak_pointer) / sizeof(lispobj)), 2)
 560
 561 static int
 562 scav_weak_pointer(lispobj *where, lispobj object)
 563 {
 564     /* Do not let GC scavenge the value slot of the weak pointer */
 565     /* (that is why it is a weak pointer).  Note:  we could use */
 566     /* the scav_unboxed method here. */
 567
 568     return WEAK_POINTER_NWORDS;
 569 }
 570
 571 \f
 572 /* initialization.  if gc_init can be moved to after core load, we could
 573  * combine these two functions */
 574
 575 void
 576 gc_init(void)
 577 {
 578     gc_init_tables();
 579     scavtab[SIMPLE_VECTOR_WIDETAG] = scav_vector;
 580     scavtab[WEAK_POINTER_WIDETAG] = scav_weak_pointer;
 581 }
 582
 583 void
 584 gc_initialize_pointers(void)
 585 {
 586     /* FIXME: We do nothing here.  We (briefly) misguidedly attempted
 587        to set current_dynamic_space to DYNAMIC_0_SPACE_START here,
 588        forgetting that (a) actually it could be the other and (b) it's
 589        set in coreparse.c anyway.  There's a FIXME note left here to
 590        note that current_dynamic_space is a violation of OAOO: we can
 591        tell which dynamic space we're currently in by looking at
 592        dynamic_space_free_pointer.  -- CSR, 2002-08-09 */
 593 }
 594
 595
 596
 597 \f
 598 /* noise to manipulate the gc trigger stuff */
 599
 600 /* Functions that substantially change the dynamic space free pointer
 601  * (collect_garbage, purify) are responsible also for resettting the
 602  * auto_gc_trigger */
 603 void set_auto_gc_trigger(os_vm_size_t dynamic_usage)
 604 {
 605     os_vm_address_t addr=(os_vm_address_t)current_dynamic_space
 606         + dynamic_usage;
 607     long length = DYNAMIC_SPACE_SIZE - dynamic_usage;
 608
 609     if (addr < (os_vm_address_t)dynamic_space_free_pointer) {
 610         fprintf(stderr,
 611            "set_auto_gc_trigger: tried to set gc trigger too low! (%d < %p)\n",
 612                 (unsigned int)dynamic_usage,
 613                 (os_vm_address_t)dynamic_space_free_pointer
 614                 - (os_vm_address_t)current_dynamic_space);
 615         lose("lost");
 616     }
 617     else if (length < 0) {
 618         fprintf(stderr,
 619                 "set_auto_gc_trigger: tried to set gc trigger too high! (%p)\n",
 620                 dynamic_usage);
 621         lose("lost");
 622     }
 623
 624     addr=os_round_up_to_page(addr);
 625     length=os_trunc_size_to_page(length);
 626
 627 #if defined(SUNOS) || defined(SOLARIS)
 628     os_invalidate(addr,length);
 629 #else
 630     os_protect(addr, length, 0);
 631 #endif
 632
 633     current_auto_gc_trigger = (lispobj *)addr;
 634 }
 635
 636 void clear_auto_gc_trigger(void)
 637 {
 638     if (current_auto_gc_trigger!=NULL){
 639 #if defined(SUNOS) || defined(SOLARIS)/* don't want to force whole space into swapping mode... */
 640         os_vm_address_t addr=(os_vm_address_t)current_auto_gc_trigger;
 641         os_vm_size_t length=
 642             DYNAMIC_SPACE_SIZE + (os_vm_address_t)current_dynamic_space - addr;
 643
 644         os_validate(addr,length);
 645 #else
 646         os_protect((os_vm_address_t)current_dynamic_space,
 647                    DYNAMIC_SPACE_SIZE,
 648                    OS_VM_PROT_ALL);
 649 #endif
 650
 651         current_auto_gc_trigger = NULL;
 652     }
 653 }