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