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
58 #define SCM_DEFAULT_MAX_SEGMENT_SIZE 2097000L /* a little less (adm) than 2 Mb */
62 #define SCM_MIN_HEAP_SEG_SIZE (8 * SCM_GC_SIZEOF_CARD)
63 #define SCM_HEAP_SEG_SIZE (16384L * sizeof (scm_t_cell))
66 #define SCM_DOUBLECELL_ALIGNED_P(x) (((2 * sizeof (scm_t_cell) - 1) & SCM_UNPACK (x)) == 0)
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
75 int scm_getenv_int (const char *var
, int def
);
78 typedef enum { return_on_error
, abort_on_error
} policy_on_error
;
85 A struct holding GC statistics on a particular type of cells.
87 typedef struct scm_t_cell_type_statistics
{
90 heap segment where the last cell was allocated
94 /* minimum yield on this list in order not to grow the heap
98 /* defines min_yield as percent of total heap size
100 int min_yield_fraction
;
102 /* number of cells per object on this list */
105 /* number of collected cells during last GC */
106 unsigned long collected
;
108 /* number of collected cells during penultimate GC */
109 unsigned long collected_1
;
111 /* total number of cells in heap segments
112 * belonging to this list.
114 unsigned long heap_size
;
117 } scm_t_cell_type_statistics
;
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
;
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
);
129 #define SCM_HEAP_SIZE \
130 (scm_i_master_freelist.heap_size + scm_i_master_freelist2.heap_size)
133 #define SCM_MAX(A, B) ((A) > (B) ? (A) : (B))
134 #define SCM_MIN(A, B) ((A) < (B) ? (A) : (B))
136 #define CELL_P(x) (SCM_ITAG3 (x) == scm_tc3_cons)
143 void scm_mark_all (void);
156 Cells are stored in a heap-segment: it is a contiguous chunk of
157 memory, that associated with one freelist.
160 typedef struct scm_t_heap_segment
163 {lower, upper} bounds of the segment
165 The upper bound is also the start of the mark space.
167 scm_t_cell
*bounds
[2];
170 If we ever decide to give it back, we could do it with this ptr.
172 Note that giving back memory is not very useful; as long we don't
173 touch a chunk of memory, the virtual memory system will keep it
174 swapped out. We could simply forget about a block.
176 (not that we do that, but anyway.)
181 scm_t_cell
* next_free_card
;
183 /* address of the head-of-freelist pointer for this segment's cells.
184 All segments usually point to the same one, scm_i_freelist. */
185 scm_t_cell_type_statistics
*freelist
;
187 /* number of cells per object in this segment */
192 Is this the first time that the cells are accessed?
196 } scm_t_heap_segment
;
202 A table of segment records is kept that records the upper and
203 lower extents of the segment; this is used during the conservative
204 phase of gc to identify probably gc roots (because they point
205 into valid segments at reasonable offsets).
208 extern scm_t_heap_segment
** scm_i_heap_segment_table
;
209 extern size_t scm_i_heap_segment_table_size
;
212 int scm_i_init_card_freelist (scm_t_cell
* card
, SCM
*free_list
,scm_t_heap_segment
*);
213 int scm_i_sweep_card (scm_t_cell
* card
, SCM
*free_list
, scm_t_heap_segment
*);
214 int scm_i_initialize_heap_segment_data (scm_t_heap_segment
* segment
, size_t requested
);
215 int scm_i_segment_card_count (scm_t_heap_segment
* seg
);
216 int scm_i_segment_cell_count (scm_t_heap_segment
* seg
);
218 void scm_i_clear_segment_mark_space (scm_t_heap_segment
*seg
);
219 scm_t_heap_segment
* scm_i_make_empty_heap_segment (scm_t_cell_type_statistics
*);
220 SCM
scm_i_sweep_some_cards (scm_t_heap_segment
*seg
);
221 void scm_i_sweep_segment (scm_t_heap_segment
* seg
);
224 int scm_i_insert_segment (scm_t_heap_segment
* seg
);
225 long int scm_i_find_heap_segment_containing_object (SCM obj
);
226 int scm_i_get_new_heap_segment (scm_t_cell_type_statistics
*, policy_on_error
);
227 void scm_i_clear_mark_space (void);
228 void scm_i_sweep_segments (void);
229 SCM
scm_i_sweep_some_segments (scm_t_cell_type_statistics
* fl
);
230 void scm_i_reset_segments (void);
231 void scm_i_sweep_all_segments (char const *reason
);
232 void scm_i_make_initial_segment (int init_heap_size
, scm_t_cell_type_statistics
*freelist
);
234 extern long int scm_i_deprecated_memory_return
;
240 void scm_gc_init_malloc (void);
241 void scm_gc_init_freelist (void);
242 void scm_gc_init_segments (void);
243 void scm_gc_init_mark (void);