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 static void scavenge_newspace(void);
  51
  52 \f
  53 /* collecting garbage */
  54
  55 #ifdef PRINTNOISE
  56 static double
  57 tv_diff(struct timeval *x, struct timeval *y)
  58 {
  59     return (((double) x->tv_sec + (double) x->tv_usec * 1.0e-6) -
  60             ((double) y->tv_sec + (double) y->tv_usec * 1.0e-6));
  61 }
  62 #endif
  63
  64 void *
  65 gc_general_alloc(word_t bytes, int page_type_flag, int quick_p) {
  66     lispobj *new=new_space_free_pointer;
  67     new_space_free_pointer+=(bytes/N_WORD_BYTES);
  68     return new;
  69 }
  70
  71 lispobj  copy_large_unboxed_object(lispobj object, sword_t nwords) {
  72     return copy_object(object,nwords);
  73 }
  74 lispobj  copy_unboxed_object(lispobj object, sword_t nwords) {
  75     return copy_object(object,nwords);
  76 }
  77 lispobj  copy_large_object(lispobj object, sword_t nwords) {
  78     return copy_object(object,nwords);
  79 }
  80
  81 /* Note: The generic GC interface we're implementing passes us a
  82  * last_generation argument. That's meaningless for us, since we're
  83  * not a generational GC. So we ignore it. */
  84 void
  85 collect_garbage(generation_index_t ignore)
  86 {
  87 #ifdef PRINTNOISE
  88     struct timeval start_tv, stop_tv;
  89     struct rusage start_rusage, stop_rusage;
  90     double real_time, system_time, user_time;
  91     double percent_retained, gc_rate;
  92     unsigned long size_discarded;
  93 #endif
  94     unsigned long size_retained;
  95     lispobj *current_static_space_free_pointer;
  96     unsigned long static_space_size;
  97     unsigned long binding_stack_size;
  98     sigset_t old;
  99     struct thread *th=arch_os_get_current_thread();
 100
 101 #ifdef PRINTNOISE
 102     printf("[Collecting garbage ... \n");
 103
 104     getrusage(RUSAGE_SELF, &start_rusage);
 105     gettimeofday(&start_tv, (struct timezone *) 0);
 106 #endif
 107
 108     /* it's possible that signals are blocked already if this was called
 109      * from a signal handler (e.g. with the sigsegv gc_trigger stuff) */
 110     block_blockable_signals(&old);
 111
 112     current_static_space_free_pointer =
 113         (lispobj *) ((unsigned long)
 114                      SymbolValue(STATIC_SPACE_FREE_POINTER,0));
 115
 116
 117     /* Set up from space and new space pointers. */
 118
 119     from_space = current_dynamic_space;
 120     from_space_free_pointer = dynamic_space_free_pointer;
 121
 122 #ifdef PRINTNOISE
 123     fprintf(stderr,"from_space = %lx\n",
 124             (unsigned long) current_dynamic_space);
 125 #endif
 126     if (current_dynamic_space == (lispobj *) DYNAMIC_0_SPACE_START)
 127         new_space = (lispobj *)DYNAMIC_1_SPACE_START;
 128     else if (current_dynamic_space == (lispobj *) DYNAMIC_1_SPACE_START)
 129         new_space = (lispobj *) DYNAMIC_0_SPACE_START;
 130     else {
 131         lose("GC lossage.  Current dynamic space is bogus!\n");
 132     }
 133     new_space_free_pointer = new_space;
 134
 135     /* Initialize the weak pointer list. */
 136     weak_pointers = (struct weak_pointer *) NULL;
 137
 138
 139     /* Scavenge all of the roots. */
 140 #ifdef PRINTNOISE
 141     printf("Scavenging interrupt contexts ...\n");
 142 #endif
 143     scavenge_interrupt_contexts(th);
 144
 145 #ifdef PRINTNOISE
 146     printf("Scavenging interrupt handlers (%d bytes) ...\n",
 147            (int)sizeof(interrupt_handlers));
 148 #endif
 149     scavenge((lispobj *) interrupt_handlers,
 150              sizeof(interrupt_handlers) / sizeof(lispobj));
 151
 152 #ifdef PRINTNOISE
 153     printf("Scavenging the control stack ...\n");
 154 #endif
 155     scavenge_control_stack(th);
 156
 157
 158     binding_stack_size =
 159         (lispobj *)get_binding_stack_pointer(th) -
 160         (lispobj *)th->binding_stack_start;
 161 #ifdef PRINTNOISE
 162     printf("Scavenging the binding stack %x - %x (%d words) ...\n",
 163            th->binding_stack_start,get_binding_stack_pointer(th),
 164            (int)(binding_stack_size));
 165 #endif
 166     scavenge(((lispobj *)th->binding_stack_start), binding_stack_size);
 167
 168     static_space_size =
 169         current_static_space_free_pointer - (lispobj *) STATIC_SPACE_START;
 170 #ifdef PRINTNOISE
 171     printf("Scavenging static space %x - %x (%d words) ...\n",
 172            STATIC_SPACE_START,current_static_space_free_pointer,
 173            (int)(static_space_size));
 174 #endif
 175     scavenge(((lispobj *)STATIC_SPACE_START), static_space_size);
 176
 177     /* Scavenge newspace. */
 178 #ifdef PRINTNOISE
 179     printf("Scavenging new space (%d bytes) ...\n",
 180            (int)((new_space_free_pointer - new_space) * sizeof(lispobj)));
 181 #endif
 182     scavenge_newspace();
 183
 184
 185 #if defined(DEBUG_PRINT_GARBAGE)
 186     print_garbage(from_space, from_space_free_pointer);
 187 #endif
 188
 189     /* Scan the weak pointers. */
 190 #ifdef PRINTNOISE
 191     printf("Scanning weak hash tables ...\n");
 192 #endif
 193     scan_weak_hash_tables();
 194
 195     /* Scan the weak pointers. */
 196 #ifdef PRINTNOISE
 197     printf("Scanning weak pointers ...\n");
 198 #endif
 199     scan_weak_pointers();
 200
 201     /* Flip spaces. */
 202 #ifdef PRINTNOISE
 203     printf("Flipping spaces ...\n");
 204 #endif
 205
 206     /* Maybe FIXME: it's possible that we could significantly reduce
 207      * RSS by zeroing the from_space or madvise(MADV_DONTNEED) or
 208      * similar os-dependent tricks here */
 209 #ifdef LISP_FEATURE_HPUX
 210     /* hpux cant handle unmapping areas that are not 100% mapped */
 211     clear_auto_gc_trigger();
 212 #endif
 213     os_zero((os_vm_address_t) from_space,
 214             (os_vm_size_t) dynamic_space_size);
 215
 216     current_dynamic_space = new_space;
 217     dynamic_space_free_pointer = new_space_free_pointer;
 218
 219 #ifdef PRINTNOISE
 220     size_discarded = (from_space_free_pointer - from_space) * sizeof(lispobj);
 221 #endif
 222     size_retained = (new_space_free_pointer - new_space) * sizeof(lispobj);
 223
 224     os_flush_icache((os_vm_address_t)new_space, size_retained);
 225
 226     /* Zero stack. */
 227 #ifdef PRINTNOISE
 228     printf("Zeroing empty part of control stack ...\n");
 229 #endif
 230     scrub_control_stack();
 231     set_auto_gc_trigger(size_retained+bytes_consed_between_gcs);
 232     thread_sigmask(SIG_SETMASK, &old, 0);
 233
 234
 235 #ifdef PRINTNOISE
 236     gettimeofday(&stop_tv, (struct timezone *) 0);
 237     getrusage(RUSAGE_SELF, &stop_rusage);
 238
 239     printf("done.]\n");
 240
 241     percent_retained = (((float) size_retained) /
 242                         ((float) size_discarded)) * 100.0;
 243
 244     printf("Total of %ld bytes out of %ld bytes retained (%3.2f%%).\n",
 245            size_retained, size_discarded, percent_retained);
 246
 247     real_time = tv_diff(&stop_tv, &start_tv);
 248     user_time = tv_diff(&stop_rusage.ru_utime, &start_rusage.ru_utime);
 249     system_time = tv_diff(&stop_rusage.ru_stime, &start_rusage.ru_stime);
 250
 251     printf("Statistics: %10.2fs real, %10.2fs user, %10.2fs system.\n",
 252            real_time, user_time, system_time);
 253
 254     gc_rate = ((float) size_retained / (float) (1<<20)) / real_time;
 255
 256     printf("%10.2f M bytes/sec collected.\n", gc_rate);
 257 #endif
 258 }
 259
 260 \f
 261 /* scavenging */
 262
 263 static void
 264 scavenge_newspace(void)
 265 {
 266     lispobj *here, *next;
 267
 268     here = new_space;
 269     while (here < new_space_free_pointer) {
 270         /*      printf("here=%lx, new_space_free_pointer=%lx\n",
 271                 here,new_space_free_pointer); */
 272         next = new_space_free_pointer;
 273         scavenge(here, next - here);
 274         scav_weak_hash_tables();
 275         here = next;
 276     }
 277     /* printf("done with newspace\n"); */
 278 }
 279 \f
 280 /* debugging code */
 281
 282 void
 283 print_garbage(lispobj *from_space, lispobj *from_space_free_pointer)
 284 {
 285     lispobj *start;
 286     int total_words_not_copied;
 287
 288     printf("Scanning from space ...\n");
 289
 290     total_words_not_copied = 0;
 291     start = from_space;
 292     while (start < from_space_free_pointer) {
 293         lispobj object;
 294         int forwardp, type, nwords;
 295         lispobj header;
 296
 297         object = *start;
 298         forwardp = is_lisp_pointer(object) && new_space_p(object);
 299
 300         if (forwardp) {
 301             int tag;
 302             lispobj *pointer;
 303
 304             tag = lowtag_of(object);
 305
 306             switch (tag) {
 307             case LIST_POINTER_LOWTAG:
 308                 nwords = 2;
 309                 break;
 310             case INSTANCE_POINTER_LOWTAG:
 311                 printf("Don't know about instances yet!\n");
 312                 nwords = 1;
 313                 break;
 314             case FUN_POINTER_LOWTAG:
 315                 nwords = 1;
 316                 break;
 317             case OTHER_POINTER_LOWTAG:
 318                 pointer = native_pointer(object);
 319                 header = *pointer;
 320                 type = widetag_of(header);
 321                 nwords = (sizetab[type])(pointer);
 322                 break;
 323             default: nwords=1;  /* shut yer whinging, gcc */
 324             }
 325         } else {
 326             type = widetag_of(object);
 327             nwords = (sizetab[type])(start);
 328             total_words_not_copied += nwords;
 329             printf("%4d words not copied at 0x%16lx; ",
 330                    nwords, (unsigned long) start);
 331             printf("Header word is 0x%08x\n",
 332                    (unsigned int) object);
 333         }
 334         start += nwords;
 335     }
 336     printf("%d total words not copied.\n", total_words_not_copied);
 337 }
 338
 339 \f
 340 /* weak pointers */
 341
 342 static sword_t
 343 scav_weak_pointer(lispobj *where, lispobj object)
 344 {
 345     /* Do not let GC scavenge the value slot of the weak pointer */
 346     /* (that is why it is a weak pointer).  Note:  we could use */
 347     /* the scav_unboxed method here. */
 348
 349     return WEAK_POINTER_NWORDS;
 350 }
 351 \f
 352 lispobj *
 353 search_read_only_space(void *pointer)
 354 {
 355     lispobj* start = (lispobj*)READ_ONLY_SPACE_START;
 356     lispobj* end = (lispobj*)SymbolValue(READ_ONLY_SPACE_FREE_POINTER,0);
 357     if ((pointer < (void *)start) || (pointer >= (void *)end))
 358         return NULL;
 359     return gc_search_space(start, pointer);
 360 }
 361
 362 lispobj *
 363 search_static_space(void *pointer)
 364 {
 365     lispobj* start = (lispobj*)STATIC_SPACE_START;
 366     lispobj* end = (lispobj*)SymbolValue(STATIC_SPACE_FREE_POINTER,0);
 367     if ((pointer < (void *)start) || (pointer >= (void *)end))
 368         return NULL;
 369     return gc_search_space(start, pointer);
 370 }
 371
 372 lispobj *
 373 search_dynamic_space(void *pointer)
 374 {
 375     lispobj *start = (lispobj *) current_dynamic_space;
 376     lispobj *end = (lispobj *) dynamic_space_free_pointer;
 377     if ((pointer < (void *)start) || (pointer >= (void *)end))
 378         return NULL;
 379     return gc_search_space(start, pointer);
 380 }
 381 \f
 382 /* initialization.  if gc_init can be moved to after core load, we could
 383  * combine these two functions */
 384
 385 void
 386 gc_init(void)
 387 {
 388     scavtab[WEAK_POINTER_WIDETAG] = scav_weak_pointer;
 389 }
 390
 391 void
 392 gc_initialize_pointers(void)
 393 {
 394     /* FIXME: We do nothing here.  We (briefly) misguidedly attempted
 395        to set current_dynamic_space to DYNAMIC_0_SPACE_START here,
 396        forgetting that (a) actually it could be the other and (b) it's
 397        set in coreparse.c anyway.  There's a FIXME note left here to
 398        note that current_dynamic_space is a violation of OAOO: we can
 399        tell which dynamic space we're currently in by looking at
 400        dynamic_space_free_pointer.  -- CSR, 2002-08-09 */
 401 }
 402
 403
 404
 405 \f
 406 /* noise to manipulate the gc trigger stuff */
 407
 408 /* Functions that substantially change the dynamic space free pointer
 409  * (collect_garbage, purify) are responsible also for resetting the
 410  * auto_gc_trigger */
 411 void set_auto_gc_trigger(os_vm_size_t dynamic_usage)
 412 {
 413     os_vm_address_t addr;
 414     os_vm_size_t length;
 415
 416     addr = os_round_up_to_page((os_vm_address_t)current_dynamic_space
 417                                + dynamic_usage);
 418     if (addr < (os_vm_address_t)dynamic_space_free_pointer)
 419         lose("set_auto_gc_trigger: tried to set gc trigger too low! (%ld < 0x%08lx)\n",
 420              (unsigned long)dynamic_usage,
 421              (unsigned long)((os_vm_address_t)dynamic_space_free_pointer
 422                              - (os_vm_address_t)current_dynamic_space));
 423
 424     if (dynamic_usage > dynamic_space_size)
 425         lose("set_auto_gc_trigger: tried to set gc trigger too high! (0x%08lx)\n",
 426              (unsigned long)dynamic_usage);
 427     length = os_trunc_size_to_page(dynamic_space_size - dynamic_usage);
 428
 429 #if defined(SUNOS) || defined(SOLARIS) || defined(LISP_FEATURE_HPUX)
 430     os_invalidate(addr, length);
 431 #else
 432     os_protect(addr, length, 0);
 433 #endif
 434
 435     current_auto_gc_trigger = (lispobj *)addr;
 436 }
 437
 438 void clear_auto_gc_trigger(void)
 439 {
 440     os_vm_address_t addr;
 441     os_vm_size_t length;
 442
 443     if (current_auto_gc_trigger == NULL)
 444         return;
 445
 446     addr = (os_vm_address_t)current_auto_gc_trigger;
 447     length = dynamic_space_size + (os_vm_address_t)current_dynamic_space - addr;
 448
 449 #if defined(SUNOS) || defined(SOLARIS) || defined(LISP_FEATURE_HPUX)
 450     /* don't want to force whole space into swapping mode... */
 451     os_validate(addr, length);
 452 #else
 453     os_protect(addr, length, OS_VM_PROT_ALL);
 454 #endif
 455
 456     current_auto_gc_trigger = NULL;
 457 }
 458
 459 static boolean
 460 gc_trigger_hit(void *addr)
 461 {
 462     if (current_auto_gc_trigger == NULL)
 463         return 0;
 464     else{
 465         return (addr >= (void *)current_auto_gc_trigger &&
 466                 addr <((void *)current_dynamic_space + dynamic_space_size));
 467     }
 468 }
 469
 470 boolean
 471 cheneygc_handle_wp_violation(os_context_t *context, void *addr)
 472 {
 473     if(!foreign_function_call_active && gc_trigger_hit(addr)){
 474         struct thread *thread=arch_os_get_current_thread();
 475         clear_auto_gc_trigger();
 476         /* Don't flood the system with interrupts if the need to gc is
 477          * already noted. This can happen for example when SUB-GC
 478          * allocates or after a gc triggered in a WITHOUT-GCING. */
 479         if (SymbolValue(GC_PENDING,thread) == NIL) {
 480             if (SymbolValue(GC_INHIBIT,thread) == NIL) {
 481                 if (arch_pseudo_atomic_atomic(context)) {
 482                     /* set things up so that GC happens when we finish
 483                      * the PA section */
 484                     SetSymbolValue(GC_PENDING,T,thread);
 485                     arch_set_pseudo_atomic_interrupted(context);
 486                     maybe_save_gc_mask_and_block_deferrables
 487                         (os_context_sigmask_addr(context));
 488                 } else {
 489                     maybe_gc(context);
 490                 }
 491             } else {
 492                 SetSymbolValue(GC_PENDING,T,thread);
 493             }
 494         }
 495         return 1;
 496     }
 497     return 0;
 498 }