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 #define SCM_DEFAULT_MAX_SEGMENT_SIZE  2097000L /* a little less (adm) than 2 Mb */
  59
  60
  61
  62 #define SCM_MIN_HEAP_SEG_SIZE (8 * SCM_GC_SIZEOF_CARD)
  63 #define SCM_HEAP_SEG_SIZE (16384L * sizeof (scm_t_cell))
  64
  65
  66 #define SCM_DOUBLECELL_ALIGNED_P(x)  (((2 * sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0)
  67
  68
  69 #define SCM_GC_CARD_BVEC_SIZE_IN_LONGS \
  70     ((SCM_GC_CARD_N_CELLS + SCM_C_BVEC_LONG_BITS - 1) / SCM_C_BVEC_LONG_BITS)
  71 #define SCM_GC_IN_CARD_HEADERP(x) \
  72   (scm_t_cell *) (x) <  SCM_GC_CELL_CARD (x) + SCM_GC_CARD_N_HEADER_CELLS
  73
  74
  75 int scm_getenv_int (const char *var, int def);
  76
  77
  78 typedef enum { return_on_error, abort_on_error } policy_on_error;
  79
  80 /* gc-freelist*/
  81
  82 /*
  83   FREELIST:
  84
  85   A struct holding GC statistics on a particular type of cells.
  86 */
  87 typedef struct scm_t_cell_type_statistics {
  88
  89   /*
  90     heap segment where the last cell was allocated
  91   */
  92   int heap_segment_idx;
  93
  94   /* minimum yield on this list in order not to grow the heap
  95    */
  96   long min_yield;
  97
  98   /* defines min_yield as percent of total heap size
  99    */
 100   int min_yield_fraction;
 101
 102   /* number of cells per object on this list */
 103   int span;
 104
 105   /* number of collected cells during last GC */
 106   unsigned long collected;
 107
 108   /* number of collected cells during penultimate GC */
 109   unsigned long collected_1;
 110
 111   /* total number of cells in heap segments
 112    * belonging to this list.
 113    */
 114   unsigned long heap_size;
 115
 116
 117 } scm_t_cell_type_statistics;
 118
 119
 120 extern scm_t_cell_type_statistics scm_i_master_freelist;
 121 extern scm_t_cell_type_statistics scm_i_master_freelist2;
 122 extern unsigned long scm_gc_cells_collected_1;
 123
 124 void scm_i_adjust_min_yield (scm_t_cell_type_statistics *freelist);
 125 void scm_i_gc_sweep_freelist_reset (scm_t_cell_type_statistics *freelist);
 126 int scm_i_gc_grow_heap_p (scm_t_cell_type_statistics * freelist);
 127
 128 #define SCM_HEAP_SIZE \
 129   (scm_i_master_freelist.heap_size + scm_i_master_freelist2.heap_size)
 130
 131
 132 #define SCM_MAX(A, B) ((A) > (B) ? (A) : (B))
 133 #define SCM_MIN(A, B) ((A) < (B) ? (A) : (B))
 134
 135 #define CELL_P(x)  (SCM_ITAG3 (x) == scm_tc3_cons)
 136
 137 /*
 138   gc-mark
 139  */
 140
 141
 142 void scm_mark_all (void);
 143
 144
 145
 146 /*
 147 gc-segment:
 148 */
 149
 150
 151
 152
 153 /*
 154
 155  Cells are stored in a heap-segment: it is a contiguous chunk of
 156  memory, that associated with one freelist.
 157 */
 158
 159 typedef struct scm_t_heap_segment
 160 {
 161   /*
 162     {lower, upper} bounds of the segment
 163
 164     The upper bound is also the start of the mark space.
 165   */
 166   scm_t_cell *bounds[2];
 167
 168   /*
 169     If we ever decide to give it back, we could do it with this ptr.
 170
 171     Note that giving back memory is not very useful; as long we don't
 172     touch a chunk of memory, the virtual memory system will keep it
 173     swapped out. We could simply forget about a block.
 174
 175     (not that we do that, but anyway.)
 176    */
 177
 178   void* malloced;
 179
 180   scm_t_cell * next_free_card;
 181
 182   /* address of the head-of-freelist pointer for this segment's cells.
 183      All segments usually point to the same one, scm_i_freelist.  */
 184   scm_t_cell_type_statistics *freelist;
 185
 186   /* number of cells per object in this segment */
 187   int span;
 188
 189
 190   /*
 191     Is this the first time that the cells are accessed?
 192    */
 193   int first_time;
 194
 195 } scm_t_heap_segment;
 196
 197
 198
 199 /*
 200
 201   A table of segment records is kept that records the upper and
 202   lower extents of the segment;  this is used during the conservative
 203   phase of gc to identify probably gc roots (because they point
 204   into valid segments at reasonable offsets).
 205
 206 */
 207 extern scm_t_heap_segment ** scm_i_heap_segment_table;
 208 extern size_t scm_i_heap_segment_table_size;
 209
 210
 211 int scm_i_init_card_freelist (scm_t_cell * card, SCM *free_list,scm_t_heap_segment*);
 212 int scm_i_sweep_card (scm_t_cell * card, SCM *free_list, scm_t_heap_segment*);
 213 int scm_i_initialize_heap_segment_data (scm_t_heap_segment * segment, size_t requested);
 214 int scm_i_segment_card_count (scm_t_heap_segment * seg);
 215 int scm_i_segment_cell_count (scm_t_heap_segment * seg);
 216
 217 void scm_i_clear_segment_mark_space (scm_t_heap_segment *seg);
 218 scm_t_heap_segment * scm_i_make_empty_heap_segment (scm_t_cell_type_statistics*);
 219 SCM scm_i_sweep_some_cards (scm_t_heap_segment *seg);
 220 void scm_i_sweep_segment (scm_t_heap_segment * seg);
 221
 222
 223 int scm_i_insert_segment (scm_t_heap_segment * seg);
 224 long int scm_i_find_heap_segment_containing_object (SCM obj);
 225 int scm_i_get_new_heap_segment (scm_t_cell_type_statistics *, policy_on_error);
 226 void scm_i_clear_mark_space (void);
 227 void scm_i_sweep_segments (void);
 228 SCM scm_i_sweep_some_segments (scm_t_cell_type_statistics * fl);
 229 void scm_i_reset_segments (void);
 230 void scm_i_sweep_all_segments (char const *reason);
 231 void scm_i_make_initial_segment (size_t init_heap_size, scm_t_cell_type_statistics *freelist);
 232
 233 extern long int scm_i_deprecated_memory_return;
 234
 235
 236 /*
 237   global init funcs.
 238  */
 239 void scm_gc_init_malloc (void);
 240 void scm_gc_init_freelist (void);
 241 void scm_gc_init_segments (void);
 242 void scm_gc_init_mark (void);
 243
 244
 245 #endif