libguile/private-gc.h

   1 /*
   2   (c) FSF 2002.
   3 */
   4
   5
   6 #ifndef PRIVATE_GC
   7 #define PRIVATE_GC
   8
   9 #include  "_scm.h"
  10
  11 /* {heap tuning parameters}
  12  *
  13  * These are parameters for controlling memory allocation.  The heap
  14  * is the area out of which scm_cons, and object headers are allocated.
  15  *
  16  * Each heap cell is 8 bytes on a 32 bit machine and 16 bytes on a
  17  * 64 bit machine.  The units of the _SIZE parameters are bytes.
  18  * Cons pairs and object headers occupy one heap cell.
  19  *
  20  * SCM_INIT_HEAP_SIZE is the initial size of heap.  If this much heap is
  21  * allocated initially the heap will grow by half its current size
  22  * each subsequent time more heap is needed.
  23  *
  24  * If SCM_INIT_HEAP_SIZE heap cannot be allocated initially, SCM_HEAP_SEG_SIZE
  25  * will be used, and the heap will grow by SCM_HEAP_SEG_SIZE when more
  26  * heap is needed.  SCM_HEAP_SEG_SIZE must fit into type size_t.  This code
  27  * is in scm_init_storage() and alloc_some_heap() in sys.c
  28  *
  29  * If SCM_INIT_HEAP_SIZE can be allocated initially, the heap will grow by
  30  * SCM_EXPHEAP(scm_heap_size) when more heap is needed.
  31  *
  32  * SCM_MIN_HEAP_SEG_SIZE is minimum size of heap to accept when more heap
  33  * is needed.
  34  */
  35
  36
  37 /*
  38  * Heap size 45000 and 40% min yield gives quick startup and no extra
  39  * heap allocation.  Having higher values on min yield may lead to
  40  * large heaps, especially if code behaviour is varying its
  41  * maximum consumption between different freelists.
  42  */
  43
  44 /*
  45   These values used to be global C variables. However, they're also
  46   available through the environment, and having a double interface is
  47   confusing. Now they're #defines --hwn.
  48  */
  49
  50 #define SCM_DEFAULT_INIT_HEAP_SIZE_1  256*1024
  51 #define SCM_DEFAULT_MIN_YIELD_1 40
  52 #define SCM_DEFAULT_INIT_HEAP_SIZE_2 32*1024
  53
  54 /* The following value may seem large, but note that if we get to GC at
  55  * all, this means that we have a numerically intensive application
  56  */
  57 #define SCM_DEFAULT_MIN_YIELD_2 40
  58
  59 #define SCM_DEFAULT_MAX_SEGMENT_SIZE  (20*1024*1024L)
  60
  61
  62
  63 #define SCM_MIN_HEAP_SEG_SIZE (8 * SCM_GC_SIZEOF_CARD)
  64 #define SCM_HEAP_SEG_SIZE (16384L * sizeof (scm_t_cell))
  65
  66
  67 #define SCM_DOUBLECELL_ALIGNED_P(x)  (((2 * sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0)
  68
  69
  70 #define SCM_GC_CARD_BVEC_SIZE_IN_LONGS \
  71     ((SCM_GC_CARD_N_CELLS + SCM_C_BVEC_LONG_BITS - 1) / SCM_C_BVEC_LONG_BITS)
  72 #define SCM_GC_IN_CARD_HEADERP(x) \
  73   (scm_t_cell *) (x) <  SCM_GC_CELL_CARD (x) + SCM_GC_CARD_N_HEADER_CELLS
  74
  75
  76 int scm_getenv_int (const char *var, int def);
  77
  78
  79 typedef enum { return_on_error, abort_on_error } policy_on_error;
  80
  81 /* gc-freelist*/
  82
  83 /*
  84   FREELIST:
  85
  86   A struct holding GC statistics on a particular type of cells.
  87 */
  88 typedef struct scm_t_cell_type_statistics {
  89
  90   /*
  91     heap segment where the last cell was allocated
  92   */
  93   int heap_segment_idx;
  94
  95   /* minimum yield on this list in order not to grow the heap
  96    */
  97   long min_yield;
  98
  99   /* defines min_yield as percent of total heap size
 100    */
 101   int min_yield_fraction;
 102
 103   /* number of cells per object on this list */
 104   int span;
 105
 106   /* number of collected cells during last GC */
 107   unsigned long collected;
 108
 109   /* number of collected cells during penultimate GC */
 110   unsigned long collected_1;
 111
 112   /* total number of cells in heap segments
 113    * belonging to this list.
 114    */
 115   unsigned long heap_size;
 116
 117
 118 } scm_t_cell_type_statistics;
 119
 120
 121 /* Sweep statistics.  */
 122 typedef struct scm_sweep_statistics
 123 {
 124   /* Number of cells "swept", i.e., visited during the sweep operation.  */
 125   unsigned swept;
 126
 127   /* Number of cells collected during the sweep operation.  This number must
 128      alsways be lower than or equal to SWEPT.  */
 129   unsigned collected;
 130 } scm_t_sweep_statistics;
 131
 132 #define scm_i_sweep_statistics_init(_stats)     \
 133   do                                            \
 134    {                                            \
 135      (_stats)->swept = (_stats)->collected = 0; \
 136    }                                            \
 137   while (0)
 138
 139 #define scm_i_sweep_statistics_sum(_sum, _addition)     \
 140   do                                                    \
 141    {                                                    \
 142      (_sum)->swept += (_addition).swept;                \
 143      (_sum)->collected += (_addition).collected;        \
 144    }                                                    \
 145   while (0)
 146
 147
 148 \f
 149 extern scm_t_cell_type_statistics scm_i_master_freelist;
 150 extern scm_t_cell_type_statistics scm_i_master_freelist2;
 151 extern unsigned long scm_gc_cells_collected_1;
 152
 153 void scm_i_adjust_min_yield (scm_t_cell_type_statistics *freelist,
 154                              scm_t_sweep_statistics sweep_stats);
 155 void scm_i_gc_sweep_freelist_reset (scm_t_cell_type_statistics *freelist);
 156 int scm_i_gc_grow_heap_p (scm_t_cell_type_statistics * freelist);
 157
 158
 159 #define SCM_HEAP_SIZE \
 160   (scm_i_master_freelist.heap_size + scm_i_master_freelist2.heap_size)
 161
 162
 163 #define SCM_MAX(A, B) ((A) > (B) ? (A) : (B))
 164 #define SCM_MIN(A, B) ((A) < (B) ? (A) : (B))
 165
 166 #define CELL_P(x)  (SCM_ITAG3 (x) == scm_tc3_cons)
 167
 168 /*
 169   gc-mark
 170  */
 171
 172
 173 void scm_mark_all (void);
 174
 175
 176
 177 /*
 178 gc-segment:
 179 */
 180
 181
 182
 183
 184 /*
 185
 186  Cells are stored in a heap-segment: it is a contiguous chunk of
 187  memory, that associated with one freelist.
 188 */
 189
 190 typedef struct scm_t_heap_segment
 191 {
 192   /*
 193     {lower, upper} bounds of the segment
 194
 195     The upper bound is also the start of the mark space.
 196   */
 197   scm_t_cell *bounds[2];
 198
 199   /*
 200     If we ever decide to give it back, we could do it with this ptr.
 201
 202     Note that giving back memory is not very useful; as long we don't
 203     touch a chunk of memory, the virtual memory system will keep it
 204     swapped out. We could simply forget about a block.
 205
 206     (not that we do that, but anyway.)
 207    */
 208
 209   void* malloced;
 210
 211   scm_t_cell * next_free_card;
 212
 213   /* address of the head-of-freelist pointer for this segment's cells.
 214      All segments usually point to the same one, scm_i_freelist.  */
 215   scm_t_cell_type_statistics *freelist;
 216
 217   /* number of cells per object in this segment */
 218   int span;
 219
 220
 221   /*
 222     Is this the first time that the cells are accessed?
 223    */
 224   int first_time;
 225
 226 } scm_t_heap_segment;
 227
 228
 229
 230 /*
 231
 232   A table of segment records is kept that records the upper and
 233   lower extents of the segment;  this is used during the conservative
 234   phase of gc to identify probably gc roots (because they point
 235   into valid segments at reasonable offsets).
 236
 237 */
 238 extern scm_t_heap_segment ** scm_i_heap_segment_table;
 239 extern size_t scm_i_heap_segment_table_size;
 240
 241
 242 int scm_i_init_card_freelist (scm_t_cell * card, SCM *free_list,scm_t_heap_segment*);
 243 int scm_i_sweep_card (scm_t_cell * card, SCM *free_list, scm_t_heap_segment*);
 244 void scm_i_card_statistics (scm_t_cell *p, SCM hashtab, scm_t_heap_segment *seg);
 245 char const *scm_i_tag_name (scm_t_bits tag); /* MOVEME */
 246
 247 int scm_i_initialize_heap_segment_data (scm_t_heap_segment * segment, size_t requested);
 248 int scm_i_segment_card_count (scm_t_heap_segment * seg);
 249 int scm_i_segment_cell_count (scm_t_heap_segment * seg);
 250
 251 void scm_i_clear_segment_mark_space (scm_t_heap_segment *seg);
 252 scm_t_heap_segment * scm_i_make_empty_heap_segment (scm_t_cell_type_statistics*);
 253 SCM scm_i_sweep_some_cards (scm_t_heap_segment *seg,
 254                             scm_t_sweep_statistics *sweep_stats);
 255 void scm_i_sweep_segment (scm_t_heap_segment *seg,
 256                           scm_t_sweep_statistics *sweep_stats);
 257
 258 void scm_i_heap_segment_statistics (scm_t_heap_segment *seg, SCM tab);
 259
 260
 261 int scm_i_insert_segment (scm_t_heap_segment * seg);
 262 long int scm_i_find_heap_segment_containing_object (SCM obj);
 263 int scm_i_get_new_heap_segment (scm_t_cell_type_statistics *, policy_on_error);
 264 void scm_i_clear_mark_space (void);
 265 void scm_i_sweep_segments (void);
 266 SCM scm_i_sweep_some_segments (scm_t_cell_type_statistics *fl,
 267                                scm_t_sweep_statistics *sweep_stats);
 268 void scm_i_reset_segments (void);
 269 void scm_i_sweep_all_segments (char const *reason,
 270                                scm_t_sweep_statistics *sweep_stats);
 271 SCM scm_i_all_segments_statistics (SCM hashtab);
 272 void scm_i_make_initial_segment (int init_heap_size, scm_t_cell_type_statistics *freelist);
 273
 274 extern long int scm_i_deprecated_memory_return;
 275
 276
 277 /*
 278   global init funcs.
 279  */
 280 void scm_gc_init_malloc (void);
 281 void scm_gc_init_freelist (void);
 282 void scm_gc_init_segments (void);
 283 void scm_gc_init_mark (void);
 284
 285
 286 #endif