1 /* -----------------------------------------------------------------------------
2 * $Id: StoragePriv.h,v 1.5 1999/01/19 17:06:05 simonm Exp $
4 * Internal Storage Manger Interface
6 * ---------------------------------------------------------------------------*/
11 /* GENERATION GC NOTES
13 * We support an arbitrary number of generations, with an arbitrary number
14 * of steps per generation. Notes (in no particular order):
16 * - all generations except the oldest should have two steps. This gives
17 * objects a decent chance to age before being promoted, and in
18 * particular will ensure that we don't end up with too many
19 * thunks being updated in older generations.
21 * - the oldest generation has one step. There's no point in aging
22 * objects in the oldest generation.
24 * - generation 0, step 0 (G0S0) is the allocation area. It is given
25 * a fixed set of blocks during initialisation, and these blocks
28 * - during garbage collection, each step which is an evacuation
29 * destination (i.e. all steps except G0S0) is allocated a to-space.
30 * evacuated objects are allocated into the step's to-space until
31 * GC is finished, when the original step's contents may be freed
32 * and replaced by the to-space.
34 * - the mutable-list is per-generation (not per-step). G0 doesn't
35 * have one (since every garbage collection collects at least G0).
37 * - block descriptors contain pointers to both the step and the
38 * generation that the block belongs to, for convenience.
40 * - static objects are stored in per-generation lists. See GC.c for
41 * details of how we collect CAFs in the generational scheme.
43 * - large objects are per-step, and are promoted in the same way
44 * as small objects, except that we may allocate large objects into
45 * generation 1 initially.
48 typedef struct _step {
49 nat no; /* step number */
50 bdescr *blocks; /* blocks in this step */
51 nat n_blocks; /* number of blocks */
52 struct _step *to; /* where collected objects from this step go */
53 struct _generation *gen; /* generation this step belongs to */
54 bdescr *large_objects; /* large objects (doubly linked) */
56 /* temporary use during GC: */
57 StgPtr hp; /* next free locn in to-space */
58 StgPtr hpLim; /* end of current to-space block */
59 bdescr *hp_bd; /* bdescr of current to-space block */
60 bdescr *to_space; /* bdescr of first to-space block */
61 nat to_blocks; /* number of blocks in to-space */
62 bdescr *scan_bd; /* block currently being scanned */
63 StgPtr scan; /* scan pointer in current block */
64 bdescr *new_large_objects; /* large objects collected so far */
65 bdescr *scavenged_large_objects; /* live large objects after GC (dbl link) */
68 typedef struct _generation {
69 nat no; /* generation number */
70 step *steps; /* steps */
71 nat n_steps; /* number of steps */
72 nat max_blocks; /* max blocks in step 0 */
73 StgMutClosure *mut_list; /* mutable objects in this generation (not G0)*/
75 /* temporary use during GC: */
76 StgMutClosure *saved_mut_list;
78 /* stats information */
80 nat failed_promotions;
83 #define END_OF_STATIC_LIST stgCast(StgClosure*,1)
85 extern generation *generations;
87 extern generation *g0;
89 extern generation *oldest_gen;
91 extern void newCAF(StgClosure*);
92 extern StgTSO *relocate_TSO(StgTSO *src, StgTSO *dest);
94 extern StgWeak *weak_ptr_list;
95 extern StgClosure *caf_list;
97 extern bdescr *small_alloc_list;
98 extern bdescr *large_alloc_list;
100 extern StgPtr alloc_Hp;
101 extern StgPtr alloc_HpLim;
103 extern bdescr *nursery;
105 extern nat nursery_blocks;
106 extern nat alloc_blocks;
107 extern nat alloc_blocks_lim;
109 extern bdescr *allocNursery (bdescr *last_bd, nat blocks);
112 dbl_link_onto(bdescr *bd, bdescr **list)
117 (*list)->back = bd; /* double-link the list */
123 * A mutable list is ended with END_MUT_LIST, so that we can use NULL
124 * as an indication that an object is not on a mutable list.
126 #define END_MUT_LIST ((StgMutClosure *)(void *)&END_MUT_LIST_closure)
129 extern void memInventory(void);
132 #endif /* STORAGEPRIV_H */