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 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     lispobj *ptr = 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(long bytes, int unboxed_p, int quick_p) {
  94     lispobj *new=new_space_free_pointer;
  95     new_space_free_pointer+=(bytes/N_WORD_BYTES);
  96     return new;
  97 }
  98
  99 lispobj  copy_large_unboxed_object(lispobj object, long nwords) {
 100     return copy_object(object,nwords);
 101 }
 102 lispobj  copy_unboxed_object(lispobj object, long nwords) {
 103     return copy_object(object,nwords);
 104 }
 105 lispobj  copy_large_object(lispobj object, long 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     /* it's possible that signals are blocked already if this was called
 140      * from a signal handler (e.g. with the sigsegv gc_trigger stuff) */
 141     sigemptyset(&tmp);
 142     sigaddset_blockable(&tmp);
 143     thread_sigmask(SIG_BLOCK, &tmp, &old);
 144
 145     current_static_space_free_pointer =
 146         (lispobj *) ((unsigned long)
 147                      SymbolValue(STATIC_SPACE_FREE_POINTER,0));
 148
 149
 150     /* Set up from space and new space pointers. */
 151
 152     from_space = current_dynamic_space;
 153     from_space_free_pointer = dynamic_space_free_pointer;
 154
 155 #ifdef PRINTNOISE
 156     fprintf(stderr,"from_space = %lx\n",
 157             (unsigned long) current_dynamic_space);
 158 #endif
 159     if (current_dynamic_space == (lispobj *) DYNAMIC_0_SPACE_START)
 160         new_space = (lispobj *)DYNAMIC_1_SPACE_START;
 161     else if (current_dynamic_space == (lispobj *) DYNAMIC_1_SPACE_START)
 162         new_space = (lispobj *) DYNAMIC_0_SPACE_START;
 163     else {
 164         lose("GC lossage.  Current dynamic space is bogus!\n");
 165     }
 166     new_space_free_pointer = new_space;
 167
 168     /* Initialize the weak pointer list. */
 169     weak_pointers = (struct weak_pointer *) NULL;
 170
 171
 172     /* Scavenge all of the roots. */
 173 #ifdef PRINTNOISE
 174     printf("Scavenging interrupt contexts ...\n");
 175 #endif
 176     scavenge_interrupt_contexts();
 177
 178 #ifdef PRINTNOISE
 179     printf("Scavenging interrupt handlers (%d bytes) ...\n",
 180            (int)sizeof(interrupt_handlers));
 181 #endif
 182     scavenge((lispobj *) data->interrupt_handlers,
 183              sizeof(data->interrupt_handlers) / sizeof(lispobj));
 184
 185     /* _size quantities are in units of sizeof(lispobj) - i.e. 4 */
 186     control_stack_size =
 187         current_control_stack_pointer-
 188         (lispobj *)th->control_stack_start;
 189 #ifdef PRINTNOISE
 190     printf("Scavenging the control stack at %p (%ld words) ...\n",
 191            ((lispobj *)th->control_stack_start),
 192            control_stack_size);
 193 #endif
 194     scavenge(((lispobj *)th->control_stack_start), control_stack_size);
 195
 196
 197     binding_stack_size =
 198         current_binding_stack_pointer -
 199         (lispobj *)th->binding_stack_start;
 200 #ifdef PRINTNOISE
 201     printf("Scavenging the binding stack %x - %x (%d words) ...\n",
 202            th->binding_stack_start,current_binding_stack_pointer,
 203            (int)(binding_stack_size));
 204 #endif
 205     scavenge(((lispobj *)th->binding_stack_start), binding_stack_size);
 206
 207     static_space_size =
 208         current_static_space_free_pointer - (lispobj *) STATIC_SPACE_START;
 209 #ifdef PRINTNOISE
 210     printf("Scavenging static space %x - %x (%d words) ...\n",
 211            STATIC_SPACE_START,current_static_space_free_pointer,
 212            (int)(static_space_size));
 213 #endif
 214     scavenge(((lispobj *)STATIC_SPACE_START), static_space_size);
 215
 216     /* Scavenge newspace. */
 217 #ifdef PRINTNOISE
 218     printf("Scavenging new space (%d bytes) ...\n",
 219            (int)((new_space_free_pointer - new_space) * sizeof(lispobj)));
 220 #endif
 221     scavenge_newspace();
 222
 223
 224 #if defined(DEBUG_PRINT_GARBAGE)
 225     print_garbage(from_space, from_space_free_pointer);
 226 #endif
 227
 228     /* Scan the weak pointers. */
 229 #ifdef PRINTNOISE
 230     printf("Scanning weak pointers ...\n");
 231 #endif
 232     scan_weak_pointers();
 233
 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         here = next;
 305     }
 306     /* printf("done with newspace\n"); */
 307 }
 308 \f
 309 /* scavenging interrupt contexts */
 310
 311 static int boxed_registers[] = BOXED_REGISTERS;
 312
 313 static void
 314 scavenge_interrupt_context(os_context_t *context)
 315 {
 316     int i;
 317 #ifdef reg_LIP
 318     unsigned long lip;
 319     unsigned long lip_offset;
 320     int lip_register_pair;
 321 #endif
 322     unsigned long pc_code_offset;
 323 #ifdef ARCH_HAS_LINK_REGISTER
 324     unsigned long lr_code_offset;
 325 #endif
 326 #ifdef ARCH_HAS_NPC_REGISTER
 327     unsigned long npc_code_offset;
 328 #endif
 329 #ifdef DEBUG_SCAVENGE_VERBOSE
 330     fprintf(stderr, "Scavenging interrupt context at 0x%x\n",context);
 331 #endif
 332     /* Find the LIP's register pair and calculate its offset */
 333     /* before we scavenge the context. */
 334 #ifdef reg_LIP
 335     lip = *os_context_register_addr(context, reg_LIP);
 336     /* 0x7FFFFFFF on 32-bit platforms;
 337        0x7FFFFFFFFFFFFFFF on 64-bit platforms */
 338     lip_offset = (((unsigned long)1) << (N_WORD_BITS - 1)) - 1;
 339     lip_register_pair = -1;
 340     for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
 341         unsigned long reg;
 342         long offset;
 343         int index;
 344
 345         index = boxed_registers[i];
 346         reg = *os_context_register_addr(context, index);
 347         /* would be using PTR if not for integer length issues */
 348         if ((reg & ~((1L<<N_LOWTAG_BITS)-1)) <= lip) {
 349             offset = lip - reg;
 350             if (offset < lip_offset) {
 351                 lip_offset = offset;
 352                 lip_register_pair = index;
 353             }
 354         }
 355     }
 356 #endif /* reg_LIP */
 357
 358     /* Compute the PC's offset from the start of the CODE */
 359     /* register. */
 360     pc_code_offset =
 361         *os_context_pc_addr(context) -
 362         *os_context_register_addr(context, reg_CODE);
 363 #ifdef ARCH_HAS_NPC_REGISTER
 364     npc_code_offset =
 365         *os_context_npc_addr(context) -
 366         *os_context_register_addr(context, reg_CODE);
 367 #endif
 368 #ifdef ARCH_HAS_LINK_REGISTER
 369     lr_code_offset =
 370         *os_context_lr_addr(context) -
 371         *os_context_register_addr(context, reg_CODE);
 372 #endif
 373
 374     /* Scavenge all boxed registers in the context. */
 375     for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
 376         int index;
 377         lispobj foo;
 378
 379         index = boxed_registers[i];
 380         foo = *os_context_register_addr(context,index);
 381         scavenge((lispobj *) &foo, 1);
 382         *os_context_register_addr(context,index) = foo;
 383
 384         /* this is unlikely to work as intended on bigendian
 385          * 64 bit platforms */
 386
 387         scavenge((lispobj *)
 388                  os_context_register_addr(context, index), 1);
 389     }
 390
 391 #ifdef reg_LIP
 392     /* Fix the LIP */
 393     *os_context_register_addr(context, reg_LIP) =
 394         *os_context_register_addr(context, lip_register_pair) + lip_offset;
 395 #endif /* reg_LIP */
 396
 397     /* Fix the PC if it was in from space */
 398     if (from_space_p(*os_context_pc_addr(context)))
 399         *os_context_pc_addr(context) =
 400             *os_context_register_addr(context, reg_CODE) + pc_code_offset;
 401 #ifdef ARCH_HAS_LINK_REGISTER
 402     /* Fix the LR ditto; important if we're being called from
 403      * an assembly routine that expects to return using blr, otherwise
 404      * harmless */
 405     if (from_space_p(*os_context_lr_addr(context)))
 406         *os_context_lr_addr(context) =
 407             *os_context_register_addr(context, reg_CODE) + lr_code_offset;
 408 #endif
 409
 410 #ifdef ARCH_HAS_NPC_REGISTER
 411     if (from_space_p(*os_context_npc_addr(context)))
 412         *os_context_npc_addr(context) =
 413             *os_context_register_addr(context, reg_CODE) + npc_code_offset;
 414 #endif
 415 }
 416
 417 void scavenge_interrupt_contexts(void)
 418 {
 419     int i, index;
 420     os_context_t *context;
 421
 422     struct thread *th=arch_os_get_current_thread();
 423
 424     index = fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,0));
 425
 426
 427 #ifdef DEBUG_SCAVENGE_VERBOSE
 428     fprintf(stderr, "%d interrupt contexts to scan\n",index);
 429 #endif
 430     for (i = 0; i < index; i++) {
 431         context = th->interrupt_contexts[i];
 432         scavenge_interrupt_context(context);
 433     }
 434 }
 435
 436 \f
 437 /* debugging code */
 438
 439 void
 440 print_garbage(lispobj *from_space, lispobj *from_space_free_pointer)
 441 {
 442     lispobj *start;
 443     int total_words_not_copied;
 444
 445     printf("Scanning from space ...\n");
 446
 447     total_words_not_copied = 0;
 448     start = from_space;
 449     while (start < from_space_free_pointer) {
 450         lispobj object;
 451         int forwardp, type, nwords;
 452         lispobj header;
 453
 454         object = *start;
 455         forwardp = is_lisp_pointer(object) && new_space_p(object);
 456
 457         if (forwardp) {
 458             int tag;
 459             lispobj *pointer;
 460
 461             tag = lowtag_of(object);
 462
 463             switch (tag) {
 464             case LIST_POINTER_LOWTAG:
 465                 nwords = 2;
 466                 break;
 467             case INSTANCE_POINTER_LOWTAG:
 468                 printf("Don't know about instances yet!\n");
 469                 nwords = 1;
 470                 break;
 471             case FUN_POINTER_LOWTAG:
 472                 nwords = 1;
 473                 break;
 474             case OTHER_POINTER_LOWTAG:
 475                 pointer = (lispobj *) native_pointer(object);
 476                 header = *pointer;
 477                 type = widetag_of(header);
 478                 nwords = (sizetab[type])(pointer);
 479                 break;
 480             default: nwords=1;  /* shut yer whinging, gcc */
 481             }
 482         } else {
 483             type = widetag_of(object);
 484             nwords = (sizetab[type])(start);
 485             total_words_not_copied += nwords;
 486             printf("%4d words not copied at 0x%16lx; ",
 487                    nwords, (unsigned long) start);
 488             printf("Header word is 0x%08x\n",
 489                    (unsigned int) object);
 490         }
 491         start += nwords;
 492     }
 493     printf("%d total words not copied.\n", total_words_not_copied);
 494 }
 495
 496 \f
 497 /* vector-like objects */
 498
 499 static long
 500 scav_vector(lispobj *where, lispobj object)
 501 {
 502     if (HeaderValue(object) == subtype_VectorValidHashing) {
 503         *where =
 504             (subtype_VectorMustRehash<<N_WIDETAG_BITS) | SIMPLE_VECTOR_WIDETAG;
 505     }
 506
 507     return 1;
 508 }
 509
 510 \f
 511 /* weak pointers */
 512
 513 #define WEAK_POINTER_NWORDS \
 514         CEILING((sizeof(struct weak_pointer) / sizeof(lispobj)), 2)
 515
 516 static long
 517 scav_weak_pointer(lispobj *where, lispobj object)
 518 {
 519     /* Do not let GC scavenge the value slot of the weak pointer */
 520     /* (that is why it is a weak pointer).  Note:  we could use */
 521     /* the scav_unboxed method here. */
 522
 523     return WEAK_POINTER_NWORDS;
 524 }
 525 \f
 526 lispobj *
 527 search_read_only_space(void *pointer)
 528 {
 529     lispobj* start = (lispobj*)READ_ONLY_SPACE_START;
 530     lispobj* end = (lispobj*)SymbolValue(READ_ONLY_SPACE_FREE_POINTER,0);
 531     if ((pointer < (void *)start) || (pointer >= (void *)end))
 532         return NULL;
 533     return (gc_search_space(start,
 534                             (((lispobj *)pointer)+2)-start,
 535                             (lispobj *)pointer));
 536 }
 537
 538 lispobj *
 539 search_static_space(void *pointer)
 540 {
 541     lispobj* start = (lispobj*)STATIC_SPACE_START;
 542     lispobj* end = (lispobj*)SymbolValue(STATIC_SPACE_FREE_POINTER,0);
 543     if ((pointer < (void *)start) || (pointer >= (void *)end))
 544         return NULL;
 545     return (gc_search_space(start,
 546                             (((lispobj *)pointer)+2)-start,
 547                             (lispobj *)pointer));
 548 }
 549
 550 lispobj *
 551 search_dynamic_space(void *pointer)
 552 {
 553     lispobj *start = (lispobj *) current_dynamic_space;
 554     lispobj *end = (lispobj *) dynamic_space_free_pointer;
 555     if ((pointer < (void *)start) || (pointer >= (void *)end))
 556         return NULL;
 557     return (gc_search_space(start,
 558                             (((lispobj *)pointer)+2)-start,
 559                             (lispobj *)pointer));
 560 }
 561 \f
 562 /* initialization.  if gc_init can be moved to after core load, we could
 563  * combine these two functions */
 564
 565 void
 566 gc_init(void)
 567 {
 568     gc_init_tables();
 569     scavtab[SIMPLE_VECTOR_WIDETAG] = scav_vector;
 570     scavtab[WEAK_POINTER_WIDETAG] = scav_weak_pointer;
 571 }
 572
 573 void
 574 gc_initialize_pointers(void)
 575 {
 576     /* FIXME: We do nothing here.  We (briefly) misguidedly attempted
 577        to set current_dynamic_space to DYNAMIC_0_SPACE_START here,
 578        forgetting that (a) actually it could be the other and (b) it's
 579        set in coreparse.c anyway.  There's a FIXME note left here to
 580        note that current_dynamic_space is a violation of OAOO: we can
 581        tell which dynamic space we're currently in by looking at
 582        dynamic_space_free_pointer.  -- CSR, 2002-08-09 */
 583 }
 584
 585
 586
 587 \f
 588 /* noise to manipulate the gc trigger stuff */
 589
 590 /* Functions that substantially change the dynamic space free pointer
 591  * (collect_garbage, purify) are responsible also for resettting the
 592  * auto_gc_trigger */
 593 void set_auto_gc_trigger(os_vm_size_t dynamic_usage)
 594 {
 595     os_vm_address_t addr=(os_vm_address_t)current_dynamic_space
 596         + dynamic_usage;
 597     long length = DYNAMIC_SPACE_SIZE - dynamic_usage;
 598
 599     if (addr < (os_vm_address_t)dynamic_space_free_pointer) {
 600         fprintf(stderr,
 601            "set_auto_gc_trigger: tried to set gc trigger too low! (%ld < 0x%08lx)\n",
 602                 (unsigned long)dynamic_usage,
 603                 (unsigned long)((os_vm_address_t)dynamic_space_free_pointer
 604                                 - (os_vm_address_t)current_dynamic_space));
 605         lose("lost");
 606     }
 607     else if (length < 0) {
 608         fprintf(stderr,
 609                 "set_auto_gc_trigger: tried to set gc trigger too high! (0x%08lx)\n",
 610                 (unsigned long)dynamic_usage);
 611         lose("lost");
 612     }
 613
 614     addr=os_round_up_to_page(addr);
 615     length=os_trunc_size_to_page(length);
 616
 617 #if defined(SUNOS) || defined(SOLARIS)
 618     os_invalidate(addr,length);
 619 #else
 620     os_protect(addr, length, 0);
 621 #endif
 622
 623     current_auto_gc_trigger = (lispobj *)addr;
 624 }
 625
 626 void clear_auto_gc_trigger(void)
 627 {
 628     if (current_auto_gc_trigger!=NULL){
 629 #if defined(SUNOS) || defined(SOLARIS)/* don't want to force whole space into swapping mode... */
 630         os_vm_address_t addr=(os_vm_address_t)current_auto_gc_trigger;
 631         os_vm_size_t length=
 632             DYNAMIC_SPACE_SIZE + (os_vm_address_t)current_dynamic_space - addr;
 633
 634         os_validate(addr,length);
 635 #else
 636         os_protect((os_vm_address_t)current_dynamic_space,
 637                    DYNAMIC_SPACE_SIZE,
 638                    OS_VM_PROT_ALL);
 639 #endif
 640
 641         current_auto_gc_trigger = NULL;
 642     }
 643 }