libguile/private-gc.h

   1 /*
   2  * private-gc.h - private declarations for garbage collection.
   3  *
   4  * Copyright (C) 2002, 03, 04, 05, 06, 07, 08 Free Software Foundation, Inc.
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  19  */
  20
  21 #ifndef PRIVATE_GC
  22 #define PRIVATE_GC
  23
  24 #include  "_scm.h"
  25
  26 /* {heap tuning parameters}
  27  *
  28  * These are parameters for controlling memory allocation.  The heap
  29  * is the area out of which scm_cons, and object headers are allocated.
  30  *
  31  * Each heap cell is 8 bytes on a 32 bit machine and 16 bytes on a
  32  * 64 bit machine.  The units of the _SIZE parameters are bytes.
  33  * Cons pairs and object headers occupy one heap cell.
  34  *
  35  * SCM_INIT_HEAP_SIZE is the initial size of heap.  If this much heap is
  36  * allocated initially the heap will grow by half its current size
  37  * each subsequent time more heap is needed.
  38  *
  39  * If SCM_INIT_HEAP_SIZE heap cannot be allocated initially, SCM_HEAP_SEG_SIZE
  40  * will be used, and the heap will grow by SCM_HEAP_SEG_SIZE when more
  41  * heap is needed.  SCM_HEAP_SEG_SIZE must fit into type size_t.  This code
  42  * is in scm_init_storage() and alloc_some_heap() in sys.c
  43  *
  44  * If SCM_INIT_HEAP_SIZE can be allocated initially, the heap will grow by
  45  * SCM_EXPHEAP(scm_heap_size) when more heap is needed.
  46  *
  47  * SCM_MIN_HEAP_SEG_SIZE is minimum size of heap to accept when more heap
  48  * is needed.
  49  */
  50
  51
  52 /*
  53  * Heap size 45000 and 40% min yield gives quick startup and no extra
  54  * heap allocation.  Having higher values on min yield may lead to
  55  * large heaps, especially if code behaviour is varying its
  56  * maximum consumption between different freelists.
  57  */
  58
  59 /*
  60   These values used to be global C variables. However, they're also
  61   available through the environment, and having a double interface is
  62   confusing. Now they're #defines --hwn.
  63  */
  64
  65 #define SCM_DEFAULT_INIT_HEAP_SIZE_1  256*1024
  66 #define SCM_DEFAULT_MIN_YIELD_1 40
  67 #define SCM_DEFAULT_INIT_HEAP_SIZE_2 32*1024
  68
  69 /* The following value may seem large, but note that if we get to GC at
  70  * all, this means that we have a numerically intensive application
  71  */
  72 #define SCM_DEFAULT_MIN_YIELD_2 40
  73
  74 #define SCM_DEFAULT_MAX_SEGMENT_SIZE  (20*1024*1024L)
  75
  76 #define SCM_MIN_HEAP_SEG_SIZE (8 * SCM_GC_SIZEOF_CARD)
  77 #define SCM_HEAP_SEG_SIZE (16384L * sizeof (scm_t_cell))
  78
  79 #define SCM_DOUBLECELL_ALIGNED_P(x)  (((2 * sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0)
  80
  81
  82 #define SCM_GC_CARD_BVEC_SIZE_IN_LONGS \
  83     ((SCM_GC_CARD_N_CELLS + SCM_C_BVEC_LONG_BITS - 1) / SCM_C_BVEC_LONG_BITS)
  84 #define SCM_GC_IN_CARD_HEADERP(x) \
  85   (scm_t_cell *) (x) <  SCM_GC_CELL_CARD (x) + SCM_GC_CARD_N_HEADER_CELLS
  86
  87
  88 int scm_getenv_int (const char *var, int def);
  89
  90
  91 typedef enum { return_on_error, abort_on_error } policy_on_error;
  92
  93 /* gc-freelist*/
  94
  95 /*
  96   FREELIST:
  97
  98   A struct holding GC statistics on a particular type of cells.
  99 */
 100 typedef struct scm_t_cell_type_statistics {
 101   /*
 102     heap segment where the last cell was allocated
 103   */
 104   int heap_segment_idx;
 105
 106   /* minimum yield on this list in order not to grow the heap
 107    */
 108   long min_yield;
 109
 110   /* defines min_yield as percent of total heap size
 111    */
 112   int min_yield_fraction;
 113
 114   /* number of cells per object on this list */
 115   int span;
 116
 117   /* number of collected cells during last GC */
 118   unsigned long collected;
 119
 120   /* number of collected cells during penultimate GC */
 121   unsigned long collected_1;
 122
 123   /* total number of cells in heap segments
 124    * belonging to this list.
 125    */
 126   unsigned long heap_size;
 127
 128
 129 } scm_t_cell_type_statistics;
 130
 131
 132 /* Sweep statistics.  */
 133 typedef struct scm_sweep_statistics
 134 {
 135   /* Number of cells "swept", i.e., visited during the sweep operation.  */
 136   unsigned swept;
 137
 138   /* Number of cells collected during the sweep operation.  This number must
 139      alsways be lower than or equal to SWEPT.  */
 140   unsigned collected;
 141 } scm_t_sweep_statistics;
 142
 143 #define scm_i_sweep_statistics_init(_stats)     \
 144   do                                            \
 145    {                                            \
 146      (_stats)->swept = (_stats)->collected = 0; \
 147    }                                            \
 148   while (0)
 149
 150 #define scm_i_sweep_statistics_sum(_sum, _addition)     \
 151   do                                                    \
 152    {                                                    \
 153      (_sum)->swept += (_addition).swept;                \
 154      (_sum)->collected += (_addition).collected;        \
 155    }                                                    \
 156   while (0)
 157
 158 \f
 159 extern scm_t_cell_type_statistics scm_i_master_freelist;
 160 extern scm_t_cell_type_statistics scm_i_master_freelist2;
 161
 162 SCM_INTERNAL
 163 void scm_i_adjust_min_yield (scm_t_cell_type_statistics *freelist,
 164                              scm_t_sweep_statistics sweep_stats,
 165                              scm_t_sweep_statistics sweep_stats_1);
 166 SCM_INTERNAL
 167 void scm_i_gc_sweep_freelist_reset (scm_t_cell_type_statistics *freelist);
 168 SCM_INTERNAL
 169 int scm_i_gc_grow_heap_p (scm_t_cell_type_statistics * freelist);
 170
 171
 172 #define SCM_HEAP_SIZE \
 173   (scm_i_master_freelist.heap_size + scm_i_master_freelist2.heap_size)
 174
 175
 176 #define SCM_MAX(A, B) ((A) > (B) ? (A) : (B))
 177 #define SCM_MIN(A, B) ((A) < (B) ? (A) : (B))
 178
 179 /* CELL_P checks a random word whether it has the right form for a
 180    pointer to a cell.  Use scm_i_find_heap_segment_containing_object
 181    to find out whether it actually points to a real cell.
 182
 183    The right form for a cell pointer is this: the low three bits must
 184    be scm_tc3_cons, and when the scm_tc3_cons tag is stripped, the
 185    resulting pointer must be correctly aligned.
 186    scm_i_initialize_heap_segment_data guarantees that the test below
 187    works.
 188 */
 189 #define CELL_P(x)  ((SCM_UNPACK(x) & (sizeof(scm_t_cell)-1)) == scm_tc3_cons)
 190
 191 /*
 192   gc-mark
 193  */
 194
 195 /* this can be used to ensure that set/clear gc marks only happen when
 196    allowed. */
 197 int scm_i_marking;
 198
 199 void scm_mark_all (void);
 200
 201 /*
 202 gc-segment:
 203 */
 204
 205 /*
 206
 207  Cells are stored in a heap-segment: it is a contiguous chunk of
 208  memory, that associated with one freelist.
 209 */
 210 typedef struct scm_t_heap_segment
 211 {
 212   /*
 213     {lower, upper} bounds of the segment
 214
 215     The upper bound is also the start of the mark space.
 216   */
 217   scm_t_cell *bounds[2];
 218
 219   /*
 220     If we ever decide to give it back, we could do it with this ptr.
 221
 222     Note that giving back memory is not very useful; as long we don't
 223     touch a chunk of memory, the virtual memory system will keep it
 224     swapped out. We could simply forget about a block.
 225
 226     (not that we do that, but anyway.)
 227    */
 228
 229   void* malloced;
 230
 231   scm_t_cell * next_free_card;
 232
 233   /* address of the head-of-freelist pointer for this segment's cells.
 234      All segments usually point to the same one, scm_i_freelist.  */
 235   scm_t_cell_type_statistics *freelist;
 236
 237   /* number of cells per object in this segment */
 238   int span;
 239
 240
 241   /*
 242     Is this the first time that the cells are accessed?
 243    */
 244   int first_time;
 245
 246 } scm_t_heap_segment;
 247
 248
 249
 250 /*
 251   A table of segment records is kept that records the upper and
 252   lower extents of the segment;  this is used during the conservative
 253   phase of gc to identify probably gc roots (because they point
 254   into valid segments at reasonable offsets).
 255 */
 256 extern scm_t_heap_segment ** scm_i_heap_segment_table;
 257 extern size_t scm_i_heap_segment_table_size;
 258
 259
 260 SCM_INTERNAL int scm_i_init_card_freelist (scm_t_cell * card, SCM *free_list,
 261                                            scm_t_heap_segment*);
 262 SCM_INTERNAL int scm_i_sweep_card (scm_t_cell *card, SCM *free_list,
 263                                    scm_t_heap_segment *);
 264 SCM_INTERNAL void scm_i_card_statistics (scm_t_cell *p, SCM hashtab,
 265                                          scm_t_heap_segment *seg);
 266 SCM_INTERNAL char const *scm_i_tag_name (scm_t_bits tag); /* MOVEME */
 267
 268 SCM_INTERNAL int scm_i_initialize_heap_segment_data (scm_t_heap_segment *seg,
 269                                                      size_t requested);
 270 SCM_INTERNAL int scm_i_segment_card_count (scm_t_heap_segment *seg);
 271 SCM_INTERNAL int scm_i_segment_cell_count (scm_t_heap_segment *seg);
 272
 273 SCM_INTERNAL void scm_i_clear_segment_mark_space (scm_t_heap_segment *seg);
 274 SCM_INTERNAL scm_t_heap_segment *
 275 scm_i_make_empty_heap_segment (scm_t_cell_type_statistics*);
 276 SCM_INTERNAL SCM scm_i_sweep_some_cards (scm_t_heap_segment *seg,
 277                                          scm_t_sweep_statistics *sweep_stats);
 278 SCM_INTERNAL void scm_i_sweep_segment (scm_t_heap_segment *seg,
 279                                        scm_t_sweep_statistics *sweep_stats);
 280
 281 SCM_INTERNAL void scm_i_heap_segment_statistics (scm_t_heap_segment *seg,
 282                                                  SCM tab);
 283
 284
 285 SCM_INTERNAL int scm_i_insert_segment (scm_t_heap_segment *seg);
 286 SCM_INTERNAL long int scm_i_find_heap_segment_containing_object (SCM obj);
 287 SCM_INTERNAL int scm_i_get_new_heap_segment (scm_t_cell_type_statistics *,
 288                                              scm_t_sweep_statistics,
 289                                              policy_on_error);
 290 SCM_INTERNAL void scm_i_clear_mark_space (void);
 291 SCM_INTERNAL void scm_i_sweep_segments (void);
 292 SCM_INTERNAL SCM scm_i_sweep_some_segments (scm_t_cell_type_statistics *fl,
 293                                             scm_t_sweep_statistics *sweep_stats);
 294 SCM_INTERNAL void scm_i_reset_segments (void);
 295 SCM_INTERNAL void scm_i_sweep_all_segments (char const *reason,
 296                                             scm_t_sweep_statistics *sweep_stats);
 297 SCM_INTERNAL SCM scm_i_all_segments_statistics (SCM hashtab);
 298 SCM_INTERNAL void scm_i_make_initial_segment (int init_heap_size,
 299                                               scm_t_cell_type_statistics *fl);
 300
 301 extern long int scm_i_deprecated_memory_return;
 302
 303 /*
 304   global init funcs.
 305  */
 306 void scm_gc_init_malloc (void);
 307 void scm_gc_init_freelist (void);
 308 void scm_gc_init_segments (void);
 309 void scm_gc_init_mark (void);
 310
 311
 312 #endif