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 #include "arch.h"
  34
  35 /* So you need to debug? */
  36 #if 0
  37 #define PRINTNOISE
  38 #define DEBUG_SPACE_PREDICATES
  39 #define DEBUG_SCAVENGE_VERBOSE
  40 #define DEBUG_COPY_VERBOSE
  41 #define DEBUG_CODE_GC
  42 #endif
  43
  44 lispobj *from_space;
  45 lispobj *from_space_free_pointer;
  46
  47 lispobj *new_space;
  48 lispobj *new_space_free_pointer;
  49
  50 /* This does nothing. It's only to satisfy a reference from gc-common. */
  51 char gc_coalesce_string_literals = 0;
  52
  53 static void scavenge_newspace(void);
  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 void *
  68 gc_general_alloc(word_t bytes, int page_type_flag, int quick_p) {
  69     lispobj *new=new_space_free_pointer;
  70     new_space_free_pointer+=(bytes/N_WORD_BYTES);
  71     return new;
  72 }
  73
  74 lispobj  copy_large_unboxed_object(lispobj object, sword_t nwords) {
  75     return copy_object(object,nwords);
  76 }
  77 lispobj  copy_unboxed_object(lispobj object, sword_t nwords) {
  78     return copy_object(object,nwords);
  79 }
  80 lispobj  copy_large_object(lispobj object, sword_t nwords) {
  81     return copy_object(object,nwords);
  82 }
  83
  84 /* Note: The generic GC interface we're implementing passes us a
  85  * last_generation argument. That's meaningless for us, since we're
  86  * not a generational GC. So we ignore it. */
  87 void
  88 collect_garbage(generation_index_t ignore)
  89 {
  90 #ifdef PRINTNOISE
  91     struct timeval start_tv, stop_tv;
  92     struct rusage start_rusage, stop_rusage;
  93     double real_time, system_time, user_time;
  94     double percent_retained, gc_rate;
  95     unsigned long size_discarded;
  96 #endif
  97     unsigned long size_retained;
  98     lispobj *current_static_space_free_pointer;
  99     sigset_t old;
 100     struct thread *th=arch_os_get_current_thread();
 101
 102 #ifdef PRINTNOISE
 103     printf("[Collecting garbage ... \n");
 104
 105     getrusage(RUSAGE_SELF, &start_rusage);
 106     gettimeofday(&start_tv, (struct timezone *) 0);
 107 #endif
 108
 109     /* it's possible that signals are blocked already if this was called
 110      * from a signal handler (e.g. with the sigsegv gc_trigger stuff) */
 111     block_blockable_signals(&old);
 112
 113     current_static_space_free_pointer = static_space_free_pointer;
 114
 115     /* Set up from space and new space pointers. */
 116
 117     from_space = current_dynamic_space;
 118     from_space_free_pointer = dynamic_space_free_pointer;
 119
 120 #ifdef PRINTNOISE
 121     fprintf(stderr,"from_space = %lx\n",
 122             (unsigned long) current_dynamic_space);
 123 #endif
 124     if (current_dynamic_space == (lispobj *) DYNAMIC_0_SPACE_START)
 125         new_space = (lispobj *)DYNAMIC_1_SPACE_START;
 126     else if (current_dynamic_space == (lispobj *) DYNAMIC_1_SPACE_START)
 127         new_space = (lispobj *) DYNAMIC_0_SPACE_START;
 128     else {
 129         lose("GC lossage.  Current dynamic space is bogus!\n");
 130     }
 131     new_space_free_pointer = new_space;
 132
 133     /* Initialize the weak pointer list. */
 134     weak_pointers = (struct weak_pointer *) NULL;
 135
 136
 137     /* Scavenge all of the roots. */
 138 #ifdef PRINTNOISE
 139     printf("Scavenging interrupt contexts ...\n");
 140 #endif
 141     scavenge_interrupt_contexts(th);
 142
 143 #ifdef PRINTNOISE
 144     printf("Scavenging interrupt handlers (%d bytes) ...\n",
 145            (int)sizeof(interrupt_handlers));
 146 #endif
 147     scavenge((lispobj *) interrupt_handlers,
 148              sizeof(interrupt_handlers) / sizeof(lispobj));
 149
 150 #ifdef PRINTNOISE
 151     printf("Scavenging the control stack ...\n");
 152 #endif
 153     scavenge_control_stack(th);
 154
 155     scav_binding_stack((lispobj*)th->binding_stack_start,
 156                        (lispobj*)get_binding_stack_pointer(th));
 157
 158 #ifdef PRINTNOISE
 159     printf("Scavenging static space %p - %p (%d words) ...\n",
 160            (void*)STATIC_SPACE_START,
 161            current_static_space_free_pointer,
 162            (int)(current_static_space_free_pointer
 163                  - (lispobj *) STATIC_SPACE_START));
 164 #endif
 165     heap_scavenge(((lispobj *)STATIC_SPACE_START),
 166                   current_static_space_free_pointer);
 167
 168     /* Scavenge newspace. */
 169 #ifdef PRINTNOISE
 170     printf("Scavenging new space (%d bytes) ...\n",
 171            (int)((new_space_free_pointer - new_space) * sizeof(lispobj)));
 172 #endif
 173     scavenge_newspace();
 174
 175
 176 #if defined(DEBUG_PRINT_GARBAGE)
 177     print_garbage(from_space, from_space_free_pointer);
 178 #endif
 179
 180     /* Scan the weak pointers. */
 181 #ifdef PRINTNOISE
 182     printf("Scanning weak hash tables ...\n");
 183 #endif
 184     scan_weak_hash_tables();
 185
 186     /* Scan the weak pointers. */
 187 #ifdef PRINTNOISE
 188     printf("Scanning weak pointers ...\n");
 189 #endif
 190     scan_weak_pointers();
 191
 192     /* Flip spaces. */
 193 #ifdef PRINTNOISE
 194     printf("Flipping spaces ...\n");
 195 #endif
 196
 197     /* Maybe FIXME: it's possible that we could significantly reduce
 198      * RSS by zeroing the from_space or madvise(MADV_DONTNEED) or
 199      * similar os-dependent tricks here */
 200 #ifdef LISP_FEATURE_HPUX
 201     /* hpux cant handle unmapping areas that are not 100% mapped */
 202     clear_auto_gc_trigger();
 203 #endif
 204     os_zero((os_vm_address_t) from_space,
 205             (os_vm_size_t) dynamic_space_size);
 206
 207     current_dynamic_space = new_space;
 208     dynamic_space_free_pointer = new_space_free_pointer;
 209
 210 #ifdef PRINTNOISE
 211     size_discarded = (from_space_free_pointer - from_space) * sizeof(lispobj);
 212 #endif
 213     size_retained = (new_space_free_pointer - new_space) * sizeof(lispobj);
 214
 215     os_flush_icache((os_vm_address_t)new_space, size_retained);
 216
 217     /* Zero stack. */
 218 #ifdef PRINTNOISE
 219     printf("Zeroing empty part of control stack ...\n");
 220 #endif
 221     scrub_control_stack();
 222     set_auto_gc_trigger(size_retained+bytes_consed_between_gcs);
 223     thread_sigmask(SIG_SETMASK, &old, 0);
 224
 225
 226 #ifdef PRINTNOISE
 227     gettimeofday(&stop_tv, (struct timezone *) 0);
 228     getrusage(RUSAGE_SELF, &stop_rusage);
 229
 230     printf("done.]\n");
 231
 232     percent_retained = (((float) size_retained) /
 233                         ((float) size_discarded)) * 100.0;
 234
 235     printf("Total of %ld bytes out of %ld bytes retained (%3.2f%%).\n",
 236            size_retained, size_discarded, percent_retained);
 237
 238     real_time = tv_diff(&stop_tv, &start_tv);
 239     user_time = tv_diff(&stop_rusage.ru_utime, &start_rusage.ru_utime);
 240     system_time = tv_diff(&stop_rusage.ru_stime, &start_rusage.ru_stime);
 241
 242     printf("Statistics: %10.2fs real, %10.2fs user, %10.2fs system.\n",
 243            real_time, user_time, system_time);
 244
 245     gc_rate = ((float) size_retained / (float) (1<<20)) / real_time;
 246
 247     printf("%10.2f M bytes/sec collected.\n", gc_rate);
 248 #endif
 249 }
 250
 251 \f
 252 /* scavenging */
 253
 254 static void
 255 scavenge_newspace(void)
 256 {
 257     lispobj *here, *next;
 258
 259     here = new_space;
 260     while (here < new_space_free_pointer) {
 261         /*      printf("here=%lx, new_space_free_pointer=%lx\n",
 262                 here,new_space_free_pointer); */
 263         next = new_space_free_pointer;
 264         heap_scavenge(here, next);
 265         scav_weak_hash_tables();
 266         here = next;
 267     }
 268     /* printf("done with newspace\n"); */
 269 }
 270 \f
 271 /* debugging code */
 272
 273 void
 274 print_garbage(lispobj *from_space, lispobj *from_space_free_pointer)
 275 {
 276     lispobj *start;
 277     int total_words_not_copied;
 278
 279     printf("Scanning from space ...\n");
 280
 281     total_words_not_copied = 0;
 282     start = from_space;
 283     while (start < from_space_free_pointer) {
 284         lispobj object;
 285         int forwardp, type, nwords;
 286         lispobj header;
 287
 288         object = *start;
 289         forwardp = is_lisp_pointer(object) && new_space_p(object);
 290
 291         if (forwardp) {
 292             int tag;
 293             lispobj *pointer;
 294
 295             tag = lowtag_of(object);
 296
 297             switch (tag) {
 298             case LIST_POINTER_LOWTAG:
 299                 nwords = 2;
 300                 break;
 301             case INSTANCE_POINTER_LOWTAG:
 302                 printf("Don't know about instances yet!\n");
 303                 nwords = 1;
 304                 break;
 305             case FUN_POINTER_LOWTAG:
 306                 nwords = 1;
 307                 break;
 308             case OTHER_POINTER_LOWTAG:
 309                 pointer = native_pointer(object);
 310                 header = *pointer;
 311                 type = widetag_of(header);
 312                 nwords = (sizetab[type])(pointer);
 313                 break;
 314             default: nwords=1;  /* shut yer whinging, gcc */
 315             }
 316         } else {
 317             type = widetag_of(object);
 318             nwords = (sizetab[type])(start);
 319             total_words_not_copied += nwords;
 320             printf("%4d words not copied at 0x%16lx; ",
 321                    nwords, (unsigned long) start);
 322             printf("Header word is 0x%08x\n",
 323                    (unsigned int) object);
 324         }
 325         start += nwords;
 326     }
 327     printf("%d total words not copied.\n", total_words_not_copied);
 328 }
 329
 330 \f
 331 /* weak pointers */
 332
 333 static sword_t
 334 scav_weak_pointer(lispobj *where, lispobj object)
 335 {
 336     /* Do not let GC scavenge the value slot of the weak pointer */
 337     /* (that is why it is a weak pointer).  Note:  we could use */
 338     /* the scav_unboxed method here. */
 339
 340     return WEAK_POINTER_NWORDS;
 341 }
 342 \f
 343 lispobj *
 344 search_read_only_space(void *pointer)
 345 {
 346     lispobj* start = (lispobj*)READ_ONLY_SPACE_START;
 347     lispobj* end = read_only_space_free_pointer;
 348     if ((pointer < (void *)start) || (pointer >= (void *)end))
 349         return NULL;
 350     return gc_search_space(start, pointer);
 351 }
 352
 353 lispobj *
 354 search_static_space(void *pointer)
 355 {
 356     lispobj* start = (lispobj*)STATIC_SPACE_START;
 357     lispobj* end = static_space_free_pointer;
 358     if ((pointer < (void *)start) || (pointer >= (void *)end))
 359         return NULL;
 360     return gc_search_space(start, pointer);
 361 }
 362
 363 lispobj *
 364 search_dynamic_space(void *pointer)
 365 {
 366     lispobj *start = (lispobj *) current_dynamic_space;
 367     lispobj *end = (lispobj *) dynamic_space_free_pointer;
 368     if ((pointer < (void *)start) || (pointer >= (void *)end))
 369         return NULL;
 370     return gc_search_space(start, pointer);
 371 }
 372 \f
 373 /* initialization.  if gc_init can be moved to after core load, we could
 374  * combine these two functions */
 375
 376 void
 377 gc_init(void)
 378 {
 379     scavtab[WEAK_POINTER_WIDETAG] = scav_weak_pointer;
 380 }
 381
 382 void
 383 gc_initialize_pointers(void)
 384 {
 385     /* FIXME: We do nothing here.  We (briefly) misguidedly attempted
 386        to set current_dynamic_space to DYNAMIC_0_SPACE_START here,
 387        forgetting that (a) actually it could be the other and (b) it's
 388        set in coreparse.c anyway.  There's a FIXME note left here to
 389        note that current_dynamic_space is a violation of OAOO: we can
 390        tell which dynamic space we're currently in by looking at
 391        dynamic_space_free_pointer.  -- CSR, 2002-08-09 */
 392 }
 393
 394
 395
 396 \f
 397 /* noise to manipulate the gc trigger stuff */
 398
 399 /* Functions that substantially change the dynamic space free pointer
 400  * (collect_garbage, purify) are responsible also for resetting the
 401  * auto_gc_trigger */
 402 void set_auto_gc_trigger(os_vm_size_t dynamic_usage)
 403 {
 404     os_vm_address_t addr;
 405     os_vm_size_t length;
 406
 407     addr = os_round_up_to_page((os_vm_address_t)current_dynamic_space
 408                                + dynamic_usage);
 409     if (addr < (os_vm_address_t)dynamic_space_free_pointer)
 410         lose("set_auto_gc_trigger: tried to set gc trigger too low! (%ld < 0x%08lx)\n",
 411              (unsigned long)dynamic_usage,
 412              (unsigned long)((os_vm_address_t)dynamic_space_free_pointer
 413                              - (os_vm_address_t)current_dynamic_space));
 414
 415     if (dynamic_usage > dynamic_space_size)
 416         lose("set_auto_gc_trigger: tried to set gc trigger too high! (0x%08lx)\n",
 417              (unsigned long)dynamic_usage);
 418     length = os_trunc_size_to_page(dynamic_space_size - dynamic_usage);
 419
 420 #if defined(SUNOS) || defined(SOLARIS) || defined(LISP_FEATURE_HPUX)
 421     os_invalidate(addr, length);
 422 #else
 423     os_protect(addr, length, 0);
 424 #endif
 425
 426     current_auto_gc_trigger = (lispobj *)addr;
 427 }
 428
 429 void clear_auto_gc_trigger(void)
 430 {
 431     os_vm_address_t addr;
 432     os_vm_size_t length;
 433
 434     if (current_auto_gc_trigger == NULL)
 435         return;
 436
 437     addr = (os_vm_address_t)current_auto_gc_trigger;
 438     length = dynamic_space_size + (os_vm_address_t)current_dynamic_space - addr;
 439
 440 #if defined(SUNOS) || defined(SOLARIS) || defined(LISP_FEATURE_HPUX)
 441     /* don't want to force whole space into swapping mode... */
 442     os_validate(NOT_MOVABLE, addr, length);
 443 #else
 444     os_protect(addr, length, OS_VM_PROT_ALL);
 445 #endif
 446
 447     current_auto_gc_trigger = NULL;
 448 }
 449
 450 static boolean
 451 gc_trigger_hit(void *addr)
 452 {
 453     if (current_auto_gc_trigger == NULL)
 454         return 0;
 455     else{
 456         return (addr >= (void *)current_auto_gc_trigger &&
 457                 (char*)addr <((char *)current_dynamic_space + dynamic_space_size));
 458     }
 459 }
 460
 461 boolean
 462 cheneygc_handle_wp_violation(os_context_t *context, void *addr)
 463 {
 464     if(!foreign_function_call_active && gc_trigger_hit(addr)){
 465         struct thread *thread=arch_os_get_current_thread();
 466         clear_auto_gc_trigger();
 467         /* Don't flood the system with interrupts if the need to gc is
 468          * already noted. This can happen for example when SUB-GC
 469          * allocates or after a gc triggered in a WITHOUT-GCING. */
 470         if (SymbolValue(GC_PENDING,thread) == NIL) {
 471             if (SymbolValue(GC_INHIBIT,thread) == NIL) {
 472                 if (arch_pseudo_atomic_atomic(context)) {
 473                     /* set things up so that GC happens when we finish
 474                      * the PA section */
 475                     SetSymbolValue(GC_PENDING,T,thread);
 476                     arch_set_pseudo_atomic_interrupted(context);
 477                     maybe_save_gc_mask_and_block_deferrables
 478                         (os_context_sigmask_addr(context));
 479                 } else {
 480                     maybe_gc(context);
 481                 }
 482             } else {
 483                 SetSymbolValue(GC_PENDING,T,thread);
 484             }
 485         }
 486         return 1;
 487     }
 488     return 0;
 489 }