1 /* -----------------------------------------------------------------------------
2 * $Id: StoragePriv.h,v 1.8 1999/02/05 16:03:02 simonm Exp $
4 * (c) The GHC Team, 1998-1999
6 * Internal Storage Manger Interface
8 * ---------------------------------------------------------------------------*/
13 /* GENERATION GC NOTES
15 * We support an arbitrary number of generations, with an arbitrary number
16 * of steps per generation. Notes (in no particular order):
18 * - all generations except the oldest should have two steps. This gives
19 * objects a decent chance to age before being promoted, and in
20 * particular will ensure that we don't end up with too many
21 * thunks being updated in older generations.
23 * - the oldest generation has one step. There's no point in aging
24 * objects in the oldest generation.
26 * - generation 0, step 0 (G0S0) is the allocation area. It is given
27 * a fixed set of blocks during initialisation, and these blocks
30 * - during garbage collection, each step which is an evacuation
31 * destination (i.e. all steps except G0S0) is allocated a to-space.
32 * evacuated objects are allocated into the step's to-space until
33 * GC is finished, when the original step's contents may be freed
34 * and replaced by the to-space.
36 * - the mutable-list is per-generation (not per-step). G0 doesn't
37 * have one (since every garbage collection collects at least G0).
39 * - block descriptors contain pointers to both the step and the
40 * generation that the block belongs to, for convenience.
42 * - static objects are stored in per-generation lists. See GC.c for
43 * details of how we collect CAFs in the generational scheme.
45 * - large objects are per-step, and are promoted in the same way
46 * as small objects, except that we may allocate large objects into
47 * generation 1 initially.
50 typedef struct _step {
51 nat no; /* step number */
52 bdescr *blocks; /* blocks in this step */
53 nat n_blocks; /* number of blocks */
54 struct _step *to; /* where collected objects from this step go */
55 struct _generation *gen; /* generation this step belongs to */
56 bdescr *large_objects; /* large objects (doubly linked) */
58 /* temporary use during GC: */
59 StgPtr hp; /* next free locn in to-space */
60 StgPtr hpLim; /* end of current to-space block */
61 bdescr *hp_bd; /* bdescr of current to-space block */
62 bdescr *to_space; /* bdescr of first to-space block */
63 nat to_blocks; /* number of blocks in to-space */
64 bdescr *scan_bd; /* block currently being scanned */
65 StgPtr scan; /* scan pointer in current block */
66 bdescr *new_large_objects; /* large objects collected so far */
67 bdescr *scavenged_large_objects; /* live large objects after GC (dbl link) */
70 typedef struct _generation {
71 nat no; /* generation number */
72 step *steps; /* steps */
73 nat n_steps; /* number of steps */
74 nat max_blocks; /* max blocks in step 0 */
75 StgMutClosure *mut_list; /* mutable objects in this generation (not G0)*/
76 StgMutClosure *mut_once_list; /* objects that point to younger generations */
78 /* temporary use during GC: */
79 StgMutClosure *saved_mut_list;
81 /* stats information */
83 nat failed_promotions;
86 #define END_OF_STATIC_LIST stgCast(StgClosure*,1)
88 extern generation *generations;
90 extern generation *g0;
92 extern generation *oldest_gen;
94 extern void newCAF(StgClosure*);
95 extern StgTSO *relocate_TSO(StgTSO *src, StgTSO *dest);
97 extern StgWeak *weak_ptr_list;
98 extern StgClosure *caf_list;
100 extern bdescr *small_alloc_list;
101 extern bdescr *large_alloc_list;
103 extern StgPtr alloc_Hp;
104 extern StgPtr alloc_HpLim;
106 extern bdescr *nursery;
108 extern nat nursery_blocks;
109 extern nat alloc_blocks;
110 extern nat alloc_blocks_lim;
112 extern bdescr *allocNursery ( bdescr *last_bd, nat blocks );
113 extern void resizeNursery ( nat blocks );
115 extern lnat calcLive( void );
116 extern lnat calcNeeded( void );
119 dbl_link_onto(bdescr *bd, bdescr **list)
124 (*list)->back = bd; /* double-link the list */
130 * A mutable list is ended with END_MUT_LIST, so that we can use NULL
131 * as an indication that an object is not on a mutable list.
133 #define END_MUT_LIST ((StgMutClosure *)(void *)&END_MUT_LIST_closure)
136 extern void memInventory(void);
137 extern void checkSanity(nat N);
140 #endif /* STORAGEPRIV_H */