11 /* {heap tuning parameters}
13 * These are parameters for controlling memory allocation. The heap
14 * is the area out of which scm_cons, and object headers are allocated.
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.
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.
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
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.
32 * SCM_MIN_HEAP_SEG_SIZE is minimum size of heap to accept when more heap
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.
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.
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
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
57 #define SCM_DEFAULT_MIN_YIELD_2 40
59 #define SCM_DEFAULT_MAX_SEGMENT_SIZE (20*1024*1024L)
63 #define SCM_MIN_HEAP_SEG_SIZE (8 * SCM_GC_SIZEOF_CARD)
64 #define SCM_HEAP_SEG_SIZE (16384L * sizeof (scm_t_cell))
67 #define SCM_DOUBLECELL_ALIGNED_P(x) (((2 * sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0)
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
76 int scm_getenv_int (const char *var
, int def
);
79 typedef enum { return_on_error
, abort_on_error
} policy_on_error
;
86 A struct holding GC statistics on a particular type of cells.
88 typedef struct scm_t_cell_type_statistics
{
91 heap segment where the last cell was allocated
95 /* minimum yield on this list in order not to grow the heap
99 /* defines min_yield as percent of total heap size
101 int min_yield_fraction
;
103 /* number of cells per object on this list */
106 /* number of collected cells during last GC */
107 unsigned long collected
;
109 /* number of collected cells during penultimate GC */
110 unsigned long collected_1
;
112 /* total number of cells in heap segments
113 * belonging to this list.
115 unsigned long heap_size
;
118 } scm_t_cell_type_statistics
;
121 /* Sweep statistics. */
122 typedef struct scm_sweep_statistics
124 /* Number of cells "swept", i.e., visited during the sweep operation. */
127 /* Number of cells collected during the sweep operation. This number must
128 alsways be lower than or equal to SWEPT. */
130 } scm_t_sweep_statistics
;
132 #define scm_i_sweep_statistics_init(_stats) \
135 (_stats)->swept = (_stats)->collected = 0; \
139 #define scm_i_sweep_statistics_sum(_sum, _addition) \
142 (_sum)->swept += (_addition).swept; \
143 (_sum)->collected += (_addition).collected; \
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
;
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
);
159 #define SCM_HEAP_SIZE \
160 (scm_i_master_freelist.heap_size + scm_i_master_freelist2.heap_size)
163 #define SCM_MAX(A, B) ((A) > (B) ? (A) : (B))
164 #define SCM_MIN(A, B) ((A) < (B) ? (A) : (B))
166 /* CELL_P checks a random word whether it has the right form for a
167 pointer to a cell. Use scm_i_find_heap_segment_containing_object
168 to find out whether it actually points to a real cell.
170 The right form for a cell pointer is this: the low three bits must
171 be scm_tc3_cons, and when the scm_tc3_cons tag is stripped, the
172 resulting pointer must be correctly aligned.
173 scm_i_initialize_heap_segment_data guarantees that the test below
176 #define CELL_P(x) ((SCM_UNPACK(x) & (sizeof(scm_t_cell)-1)) == scm_tc3_cons)
183 void scm_mark_all (void);
196 Cells are stored in a heap-segment: it is a contiguous chunk of
197 memory, that associated with one freelist.
200 typedef struct scm_t_heap_segment
203 {lower, upper} bounds of the segment
205 The upper bound is also the start of the mark space.
207 scm_t_cell
*bounds
[2];
210 If we ever decide to give it back, we could do it with this ptr.
212 Note that giving back memory is not very useful; as long we don't
213 touch a chunk of memory, the virtual memory system will keep it
214 swapped out. We could simply forget about a block.
216 (not that we do that, but anyway.)
221 scm_t_cell
* next_free_card
;
223 /* address of the head-of-freelist pointer for this segment's cells.
224 All segments usually point to the same one, scm_i_freelist. */
225 scm_t_cell_type_statistics
*freelist
;
227 /* number of cells per object in this segment */
232 Is this the first time that the cells are accessed?
236 } scm_t_heap_segment
;
242 A table of segment records is kept that records the upper and
243 lower extents of the segment; this is used during the conservative
244 phase of gc to identify probably gc roots (because they point
245 into valid segments at reasonable offsets).
248 extern scm_t_heap_segment
** scm_i_heap_segment_table
;
249 extern size_t scm_i_heap_segment_table_size
;
252 int scm_i_init_card_freelist (scm_t_cell
* card
, SCM
*free_list
,scm_t_heap_segment
*);
253 int scm_i_sweep_card (scm_t_cell
* card
, SCM
*free_list
, scm_t_heap_segment
*);
254 void scm_i_card_statistics (scm_t_cell
*p
, SCM hashtab
, scm_t_heap_segment
*seg
);
255 char const *scm_i_tag_name (scm_t_bits tag
); /* MOVEME */
257 int scm_i_initialize_heap_segment_data (scm_t_heap_segment
* segment
, size_t requested
);
258 int scm_i_segment_card_count (scm_t_heap_segment
* seg
);
259 int scm_i_segment_cell_count (scm_t_heap_segment
* seg
);
261 void scm_i_clear_segment_mark_space (scm_t_heap_segment
*seg
);
262 scm_t_heap_segment
* scm_i_make_empty_heap_segment (scm_t_cell_type_statistics
*);
263 SCM
scm_i_sweep_some_cards (scm_t_heap_segment
*seg
,
264 scm_t_sweep_statistics
*sweep_stats
);
265 void scm_i_sweep_segment (scm_t_heap_segment
*seg
,
266 scm_t_sweep_statistics
*sweep_stats
);
268 void scm_i_heap_segment_statistics (scm_t_heap_segment
*seg
, SCM tab
);
271 int scm_i_insert_segment (scm_t_heap_segment
* seg
);
272 long int scm_i_find_heap_segment_containing_object (SCM obj
);
273 int scm_i_get_new_heap_segment (scm_t_cell_type_statistics
*, policy_on_error
);
274 void scm_i_clear_mark_space (void);
275 void scm_i_sweep_segments (void);
276 SCM
scm_i_sweep_some_segments (scm_t_cell_type_statistics
*fl
,
277 scm_t_sweep_statistics
*sweep_stats
);
278 void scm_i_reset_segments (void);
279 void scm_i_sweep_all_segments (char const *reason
,
280 scm_t_sweep_statistics
*sweep_stats
);
281 SCM
scm_i_all_segments_statistics (SCM hashtab
);
282 void scm_i_make_initial_segment (int init_heap_size
, scm_t_cell_type_statistics
*freelist
);
284 extern long int scm_i_deprecated_memory_return
;
290 void scm_gc_init_malloc (void);
291 void scm_gc_init_freelist (void);
292 void scm_gc_init_segments (void);
293 void scm_gc_init_mark (void);