*/
static rtsBool failed_to_evac;
-/* Old to-space (used for two-space collector only)
+/* Saved nursery (used for 2-space collector only)
*/
-static bdescr *old_to_blocks;
-
+static bdescr *saved_nursery;
+static nat saved_n_blocks;
+
/* Data used for allocation area sizing.
*/
static lnat new_blocks; // blocks allocated during this GC
+static lnat new_scavd_blocks; // ditto, but depth-first blocks
static lnat g0s0_pcnt_kept = 30; // percentage of g0s0 live at last minor GC
/* Used to avoid long recursion due to selector thunks
}
// Start a new to-space block, chain it on after the previous one.
- if (stp->hp_bd == NULL) {
- stp->hp_bd = bd;
- } else {
+ if (stp->hp_bd != NULL) {
stp->hp_bd->free = stp->hp;
stp->hp_bd->link = bd;
- stp->hp_bd = bd;
}
+ stp->hp_bd = bd;
stp->hp = bd->start;
stp->hpLim = stp->hp + BLOCK_SIZE_W;
- stp->n_to_blocks++;
+ stp->n_blocks++;
new_blocks++;
return bd;
}
+static bdescr *
+gc_alloc_scavd_block(step *stp)
+{
+ bdescr *bd = allocBlock();
+ bd->gen_no = stp->gen_no;
+ bd->step = stp;
+
+ // blocks in to-space in generations up to and including N
+ // get the BF_EVACUATED flag.
+ if (stp->gen_no <= N) {
+ bd->flags = BF_EVACUATED;
+ } else {
+ bd->flags = 0;
+ }
+
+ bd->link = stp->blocks;
+ stp->blocks = bd;
+
+ if (stp->scavd_hp != NULL) {
+ Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
+ }
+ stp->scavd_hp = bd->start;
+ stp->scavd_hpLim = stp->scavd_hp + BLOCK_SIZE_W;
+
+ stp->n_blocks++;
+ new_scavd_blocks++;
+
+ return bd;
+}
+
/* -----------------------------------------------------------------------------
GarbageCollect
{
bdescr *bd;
step *stp;
- lnat live, allocated, collected = 0, copied = 0;
+ lnat live, allocated, collected = 0, copied = 0, scavd_copied = 0;
lnat oldgen_saved_blocks = 0;
nat g, s;
static_objects = END_OF_STATIC_LIST;
scavenged_static_objects = END_OF_STATIC_LIST;
- /* Save the old to-space if we're doing a two-space collection
+ /* Save the nursery if we're doing a two-space collection.
+ * g0s0->blocks will be used for to-space, so we need to get the
+ * nursery out of the way.
*/
if (RtsFlags.GcFlags.generations == 1) {
- old_to_blocks = g0s0->to_blocks;
- g0s0->to_blocks = NULL;
- g0s0->n_to_blocks = 0;
+ saved_nursery = g0s0->blocks;
+ saved_n_blocks = g0s0->n_blocks;
+ g0s0->blocks = NULL;
+ g0s0->n_blocks = 0;
}
/* Keep a count of how many new blocks we allocated during this GC
* (used for resizing the allocation area, later).
*/
new_blocks = 0;
+ new_scavd_blocks = 0;
// Initialise to-space in all the generations/steps that we're
// collecting.
ASSERT(stp->gen_no == g);
// start a new to-space for this step.
- stp->hp = NULL;
- stp->hp_bd = NULL;
- stp->to_blocks = NULL;
+ stp->old_blocks = stp->blocks;
+ stp->n_old_blocks = stp->n_blocks;
// allocate the first to-space block; extra blocks will be
// chained on as necessary.
+ stp->hp_bd = NULL;
bd = gc_alloc_block(stp);
- stp->to_blocks = bd;
+ stp->blocks = bd;
+ stp->n_blocks = 1;
stp->scan = bd->start;
stp->scan_bd = bd;
+ // allocate a block for "already scavenged" objects. This goes
+ // on the front of the stp->blocks list, so it won't be
+ // traversed by the scavenging sweep.
+ gc_alloc_scavd_block(stp);
+
// initialise the large object queues.
stp->new_large_objects = NULL;
stp->scavenged_large_objects = NULL;
bdescr *bitmap_bdescr;
StgWord *bitmap;
- bitmap_size = stp->n_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
+ bitmap_size = stp->n_old_blocks * BLOCK_SIZE / (sizeof(W_)*BITS_PER_BYTE);
if (bitmap_size > 0) {
bitmap_bdescr = allocGroup((lnat)BLOCK_ROUND_UP(bitmap_size)
// For each block in this step, point to its bitmap from the
// block descriptor.
- for (bd=stp->blocks; bd != NULL; bd = bd->link) {
+ for (bd=stp->old_blocks; bd != NULL; bd = bd->link) {
bd->u.bitmap = bitmap;
bitmap += BLOCK_SIZE_W / (sizeof(W_)*BITS_PER_BYTE);
stp->blocks = bd;
stp->n_blocks = 1;
}
+ if (stp->scavd_hp == NULL) {
+ gc_alloc_scavd_block(stp);
+ stp->n_blocks++;
+ }
/* Set the scan pointer for older generations: remember we
* still have to scavenge objects that have been promoted. */
stp->scan = stp->hp;
stp->scan_bd = stp->hp_bd;
- stp->to_blocks = NULL;
- stp->n_to_blocks = 0;
stp->new_large_objects = NULL;
stp->scavenged_large_objects = NULL;
stp->n_scavenged_large_blocks = 0;
if (!(g == 0 && s == 0 && RtsFlags.GcFlags.generations > 1)) {
ASSERT(Bdescr(stp->hp) == stp->hp_bd);
stp->hp_bd->free = stp->hp;
+ Bdescr(stp->scavd_hp)->free = stp->scavd_hp;
}
}
}
// Finally: compaction of the oldest generation.
if (major_gc && oldest_gen->steps[0].is_compacted) {
// save number of blocks for stats
- oldgen_saved_blocks = oldest_gen->steps[0].n_blocks;
+ oldgen_saved_blocks = oldest_gen->steps[0].n_old_blocks;
compact(get_roots);
}
/* run through all the generations/steps and tidy up
*/
copied = new_blocks * BLOCK_SIZE_W;
+ scavd_copied = new_scavd_blocks * BLOCK_SIZE_W;
for (g = 0; g < RtsFlags.GcFlags.generations; g++) {
if (g <= N) {
if (g <= N) {
copied -= stp->hp_bd->start + BLOCK_SIZE_W -
stp->hp_bd->free;
+ scavd_copied -= (P_)(BLOCK_ROUND_UP(stp->scavd_hp)) - stp->scavd_hp;
}
}
// rough calculation of garbage collected, for stats output
if (stp->is_compacted) {
- collected += (oldgen_saved_blocks - stp->n_blocks) * BLOCK_SIZE_W;
+ collected += (oldgen_saved_blocks - stp->n_old_blocks) * BLOCK_SIZE_W;
} else {
if (g == 0 && s == 0) {
collected += countNurseryBlocks() * BLOCK_SIZE_W;
collected += alloc_blocks;
} else {
- collected += stp->n_blocks * BLOCK_SIZE_W;
+ collected += stp->n_old_blocks * BLOCK_SIZE_W;
}
}
if (stp->is_compacted) {
// for a compacted step, just shift the new to-space
// onto the front of the now-compacted existing blocks.
- for (bd = stp->to_blocks; bd != NULL; bd = bd->link) {
+ for (bd = stp->blocks; bd != NULL; bd = bd->link) {
bd->flags &= ~BF_EVACUATED; // now from-space
}
// tack the new blocks on the end of the existing blocks
- if (stp->blocks == NULL) {
- stp->blocks = stp->to_blocks;
- } else {
- for (bd = stp->blocks; bd != NULL; bd = next) {
+ if (stp->old_blocks != NULL) {
+ for (bd = stp->old_blocks; bd != NULL; bd = next) {
next = bd->link;
if (next == NULL) {
- bd->link = stp->to_blocks;
+ bd->link = stp->blocks;
}
// NB. this step might not be compacted next
// time, so reset the BF_COMPACTED flags.
// compact. (search for BF_COMPACTED above).
bd->flags &= ~BF_COMPACTED;
}
+ stp->blocks = stp->old_blocks;
}
// add the new blocks to the block tally
- stp->n_blocks += stp->n_to_blocks;
+ stp->n_blocks += stp->n_old_blocks;
} else {
- freeChain(stp->blocks);
- stp->blocks = stp->to_blocks;
- stp->n_blocks = stp->n_to_blocks;
+ freeChain(stp->old_blocks);
for (bd = stp->blocks; bd != NULL; bd = bd->link) {
bd->flags &= ~BF_EVACUATED; // now from-space
}
}
- stp->to_blocks = NULL;
- stp->n_to_blocks = 0;
+ stp->old_blocks = NULL;
+ stp->n_old_blocks = 0;
}
/* LARGE OBJECTS. The current live large objects are chained on
}
// add the new blocks we promoted during this GC
- stp->n_blocks += stp->n_to_blocks;
- stp->n_to_blocks = 0;
stp->n_large_blocks += stp->n_scavenged_large_blocks;
}
}
if (RtsFlags.GcFlags.generations == 1) {
nat blocks;
- if (old_to_blocks != NULL) {
- freeChain(old_to_blocks);
+ if (g0s0->old_blocks != NULL) {
+ freeChain(g0s0->old_blocks);
}
- for (bd = g0s0->to_blocks; bd != NULL; bd = bd->link) {
+ for (bd = g0s0->blocks; bd != NULL; bd = bd->link) {
bd->flags = 0; // now from-space
}
+ g0s0->old_blocks = g0s0->blocks;
+ g0s0->n_old_blocks = g0s0->n_blocks;
+ g0s0->blocks = saved_nursery;
+ g0s0->n_blocks = saved_n_blocks;
/* For a two-space collector, we need to resize the nursery. */
* performance we get from 3L bytes, reducing to the same
* performance at 2L bytes.
*/
- blocks = g0s0->n_to_blocks;
+ blocks = g0s0->n_old_blocks;
if ( RtsFlags.GcFlags.maxHeapSize != 0 &&
blocks * RtsFlags.GcFlags.oldGenFactor * 2 >
#endif
// ok, GC over: tell the stats department what happened.
- stat_endGC(allocated, collected, live, copied, N);
+ stat_endGC(allocated, collected, live, copied, scavd_copied, N);
#if defined(RTS_USER_SIGNALS)
// unblock signals again
STATIC_INLINE StgClosure *
copy(StgClosure *src, nat size, step *stp)
{
- P_ to, from, dest;
+ StgPtr to, from;
+ nat i;
#ifdef PROFILING
// @LDV profiling
nat size_org = size;
gc_alloc_block(stp);
}
- for(to = stp->hp, from = (P_)src; size>0; --size) {
- *to++ = *from++;
+ to = stp->hp;
+ from = (StgPtr)src;
+ stp->hp = to + size;
+ for (i = 0; i < size; i++) { // unroll for small i
+ to[i] = from[i];
}
+ upd_evacuee((StgClosure *)from,(StgClosure *)to);
- dest = stp->hp;
- stp->hp = to;
- upd_evacuee(src,(StgClosure *)dest);
#ifdef PROFILING
// We store the size of the just evacuated object in the LDV word so that
// the profiler can guess the position of the next object later.
- SET_EVACUAEE_FOR_LDV(src, size_org);
+ SET_EVACUAEE_FOR_LDV(from, size_org);
#endif
- return (StgClosure *)dest;
+ return (StgClosure *)to;
+}
+
+// Same as copy() above, except the object will be allocated in memory
+// that will not be scavenged. Used for object that have no pointer
+// fields.
+STATIC_INLINE StgClosure *
+copy_noscav(StgClosure *src, nat size, step *stp)
+{
+ StgPtr to, from;
+ nat i;
+#ifdef PROFILING
+ // @LDV profiling
+ nat size_org = size;
+#endif
+
+ TICK_GC_WORDS_COPIED(size);
+ /* Find out where we're going, using the handy "to" pointer in
+ * the step of the source object. If it turns out we need to
+ * evacuate to an older generation, adjust it here (see comment
+ * by evacuate()).
+ */
+ if (stp->gen_no < evac_gen) {
+#ifdef NO_EAGER_PROMOTION
+ failed_to_evac = rtsTrue;
+#else
+ stp = &generations[evac_gen].steps[0];
+#endif
+ }
+
+ /* chain a new block onto the to-space for the destination step if
+ * necessary.
+ */
+ if (stp->scavd_hp + size >= stp->scavd_hpLim) {
+ gc_alloc_scavd_block(stp);
+ }
+
+ to = stp->scavd_hp;
+ from = (StgPtr)src;
+ stp->scavd_hp = to + size;
+ for (i = 0; i < size; i++) { // unroll for small i
+ to[i] = from[i];
+ }
+ upd_evacuee((StgClosure *)from,(StgClosure *)to);
+
+#ifdef PROFILING
+ // We store the size of the just evacuated object in the LDV word so that
+ // the profiler can guess the position of the next object later.
+ SET_EVACUAEE_FOR_LDV(from, size_org);
+#endif
+ return (StgClosure *)to;
}
/* Special version of copy() for when we only want to copy the info
const StgInfoTable *info;
loop:
- if (HEAP_ALLOCED(q)) {
- bd = Bdescr((P_)q);
+ ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
- if (bd->gen_no > N) {
- /* Can't evacuate this object, because it's in a generation
- * older than the ones we're collecting. Let's hope that it's
- * in evac_gen or older, or we will have to arrange to track
- * this pointer using the mutable list.
- */
- if (bd->gen_no < evac_gen) {
- // nope
- failed_to_evac = rtsTrue;
- TICK_GC_FAILED_PROMOTION();
- }
- return q;
- }
+ if (!HEAP_ALLOCED(q)) {
- /* evacuate large objects by re-linking them onto a different list.
- */
- if (bd->flags & BF_LARGE) {
- info = get_itbl(q);
- if (info->type == TSO &&
- ((StgTSO *)q)->what_next == ThreadRelocated) {
- q = (StgClosure *)((StgTSO *)q)->link;
- goto loop;
- }
- evacuate_large((P_)q);
- return q;
- }
+ if (!major_gc) return q;
- /* If the object is in a step that we're compacting, then we
- * need to use an alternative evacuate procedure.
- */
- if (bd->flags & BF_COMPACTED) {
- if (!is_marked((P_)q,bd)) {
- mark((P_)q,bd);
- if (mark_stack_full()) {
- mark_stack_overflowed = rtsTrue;
- reset_mark_stack();
- }
- push_mark_stack((P_)q);
- }
- return q;
- }
+ info = get_itbl(q);
+ switch (info->type) {
- /* Object is not already evacuated. */
- ASSERT((bd->flags & BF_EVACUATED) == 0);
+ case THUNK_STATIC:
+ if (info->srt_bitmap != 0 &&
+ *THUNK_STATIC_LINK((StgClosure *)q) == NULL) {
+ *THUNK_STATIC_LINK((StgClosure *)q) = static_objects;
+ static_objects = (StgClosure *)q;
+ }
+ return q;
+
+ case FUN_STATIC:
+ if (info->srt_bitmap != 0 &&
+ *FUN_STATIC_LINK((StgClosure *)q) == NULL) {
+ *FUN_STATIC_LINK((StgClosure *)q) = static_objects;
+ static_objects = (StgClosure *)q;
+ }
+ return q;
+
+ case IND_STATIC:
+ /* If q->saved_info != NULL, then it's a revertible CAF - it'll be
+ * on the CAF list, so don't do anything with it here (we'll
+ * scavenge it later).
+ */
+ if (((StgIndStatic *)q)->saved_info == NULL
+ && *IND_STATIC_LINK((StgClosure *)q) == NULL) {
+ *IND_STATIC_LINK((StgClosure *)q) = static_objects;
+ static_objects = (StgClosure *)q;
+ }
+ return q;
+
+ case CONSTR_STATIC:
+ if (*STATIC_LINK(info,(StgClosure *)q) == NULL) {
+ *STATIC_LINK(info,(StgClosure *)q) = static_objects;
+ static_objects = (StgClosure *)q;
+ }
+ return q;
+
+ case CONSTR_INTLIKE:
+ case CONSTR_CHARLIKE:
+ case CONSTR_NOCAF_STATIC:
+ /* no need to put these on the static linked list, they don't need
+ * to be scavenged.
+ */
+ return q;
+
+ default:
+ barf("evacuate(static): strange closure type %d", (int)(info->type));
+ }
+ }
- stp = bd->step->to;
+ bd = Bdescr((P_)q);
+
+ if (bd->gen_no > N) {
+ /* Can't evacuate this object, because it's in a generation
+ * older than the ones we're collecting. Let's hope that it's
+ * in evac_gen or older, or we will have to arrange to track
+ * this pointer using the mutable list.
+ */
+ if (bd->gen_no < evac_gen) {
+ // nope
+ failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ return q;
}
-#ifdef DEBUG
- else stp = NULL; // make sure copy() will crash if HEAP_ALLOCED is wrong
-#endif
- // make sure the info pointer is into text space
- ASSERT(LOOKS_LIKE_CLOSURE_PTR(q));
+ if ((bd->flags & (BF_LARGE | BF_COMPACTED | BF_EVACUATED)) != 0) {
+
+ /* pointer into to-space: just return it. This normally
+ * shouldn't happen, but alllowing it makes certain things
+ * slightly easier (eg. the mutable list can contain the same
+ * object twice, for example).
+ */
+ if (bd->flags & BF_EVACUATED) {
+ if (bd->gen_no < evac_gen) {
+ failed_to_evac = rtsTrue;
+ TICK_GC_FAILED_PROMOTION();
+ }
+ return q;
+ }
+
+ /* evacuate large objects by re-linking them onto a different list.
+ */
+ if (bd->flags & BF_LARGE) {
+ info = get_itbl(q);
+ if (info->type == TSO &&
+ ((StgTSO *)q)->what_next == ThreadRelocated) {
+ q = (StgClosure *)((StgTSO *)q)->link;
+ goto loop;
+ }
+ evacuate_large((P_)q);
+ return q;
+ }
+
+ /* If the object is in a step that we're compacting, then we
+ * need to use an alternative evacuate procedure.
+ */
+ if (bd->flags & BF_COMPACTED) {
+ if (!is_marked((P_)q,bd)) {
+ mark((P_)q,bd);
+ if (mark_stack_full()) {
+ mark_stack_overflowed = rtsTrue;
+ reset_mark_stack();
+ }
+ push_mark_stack((P_)q);
+ }
+ return q;
+ }
+ }
+
+ stp = bd->step->to;
+
info = get_itbl(q);
- switch (info -> type) {
+ switch (info->type) {
case MUT_VAR:
case MVAR:
(StgInt)w >= MIN_INTLIKE && (StgInt)w <= MAX_INTLIKE) {
return (StgClosure *)INTLIKE_CLOSURE((StgInt)w);
}
- // else, fall through ...
+ // else
+ return copy_noscav(q,sizeofW(StgHeader)+1,stp);
}
- case FUN_1_0:
case FUN_0_1:
+ case FUN_1_0:
case CONSTR_1_0:
return copy(q,sizeofW(StgHeader)+1,stp);
return copy(q,sizeofW(StgThunk)+1,stp);
case THUNK_1_1:
- case THUNK_0_2:
case THUNK_2_0:
+ case THUNK_0_2:
#ifdef NO_PROMOTE_THUNKS
if (bd->gen_no == 0 &&
bd->step->no != 0 &&
return copy(q,sizeofW(StgThunk)+2,stp);
case FUN_1_1:
- case FUN_0_2:
case FUN_2_0:
case CONSTR_1_1:
- case CONSTR_0_2:
case CONSTR_2_0:
+ case FUN_0_2:
return copy(q,sizeofW(StgHeader)+2,stp);
+ case CONSTR_0_2:
+ return copy_noscav(q,sizeofW(StgHeader)+2,stp);
+
case THUNK:
return copy(q,thunk_sizeW_fromITBL(info),stp);
case IND_PERM:
case IND_OLDGEN_PERM:
case WEAK:
- case FOREIGN:
case STABLE_NAME:
return copy(q,sizeW_fromITBL(info),stp);
q = ((StgInd*)q)->indirectee;
goto loop;
- case THUNK_STATIC:
- if (info->srt_bitmap != 0 && major_gc &&
- *THUNK_STATIC_LINK((StgClosure *)q) == NULL) {
- *THUNK_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case FUN_STATIC:
- if (info->srt_bitmap != 0 && major_gc &&
- *FUN_STATIC_LINK((StgClosure *)q) == NULL) {
- *FUN_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case IND_STATIC:
- /* If q->saved_info != NULL, then it's a revertible CAF - it'll be
- * on the CAF list, so don't do anything with it here (we'll
- * scavenge it later).
- */
- if (major_gc
- && ((StgIndStatic *)q)->saved_info == NULL
- && *IND_STATIC_LINK((StgClosure *)q) == NULL) {
- *IND_STATIC_LINK((StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case CONSTR_STATIC:
- if (major_gc && *STATIC_LINK(info,(StgClosure *)q) == NULL) {
- *STATIC_LINK(info,(StgClosure *)q) = static_objects;
- static_objects = (StgClosure *)q;
- }
- return q;
-
- case CONSTR_INTLIKE:
- case CONSTR_CHARLIKE:
- case CONSTR_NOCAF_STATIC:
- /* no need to put these on the static linked list, they don't need
- * to be scavenged.
- */
- return q;
-
case RET_BCO:
case RET_SMALL:
case RET_VEC_SMALL:
* set the failed_to_evac flag to indicate that we couldn't
* manage to promote the object to the desired generation.
*/
- if (evac_gen > 0) { // optimisation
+ /*
+ * Optimisation: the check is fairly expensive, but we can often
+ * shortcut it if either the required generation is 0, or the
+ * current object (the EVACUATED) is in a high enough generation.
+ * stp is the lowest step that the current object would be
+ * evacuated to, so we only do the full check if stp is too low.
+ */
+ if (evac_gen > 0 && stp->gen_no < evac_gen) { // optimisation
StgClosure *p = ((StgEvacuated*)q)->evacuee;
if (HEAP_ALLOCED(p) && Bdescr((P_)p)->gen_no < evac_gen) {
failed_to_evac = rtsTrue;
case ARR_WORDS:
// just copy the block
- return copy(q,arr_words_sizeW((StgArrWords *)q),stp);
+ return copy_noscav(q,arr_words_sizeW((StgArrWords *)q),stp);
case MUT_ARR_PTRS:
case MUT_ARR_PTRS_FROZEN:
{
StgThunkInfoTable *thunk_info;
+ if (!major_gc) return;
+
thunk_info = itbl_to_thunk_itbl(info);
scavenge_srt((StgClosure **)GET_SRT(thunk_info), thunk_info->i.srt_bitmap);
}
{
StgFunInfoTable *fun_info;
+ if (!major_gc) return;
+
fun_info = itbl_to_fun_itbl(info);
scavenge_srt((StgClosure **)GET_FUN_SRT(fun_info), fun_info->i.srt_bitmap);
}
gen_obj:
case CONSTR:
case WEAK:
- case FOREIGN:
case STABLE_NAME:
{
StgPtr end;
gen_obj:
case CONSTR:
case WEAK:
- case FOREIGN:
case STABLE_NAME:
{
StgPtr end;
case CONSTR_0_2:
case CONSTR_2_0:
case WEAK:
- case FOREIGN:
case IND_PERM:
{
StgPtr q, end;
p = scavenge_small_bitmap(p, size, bitmap);
follow_srt:
- scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap);
+ if (major_gc)
+ scavenge_srt((StgClosure **)GET_SRT(info), info->i.srt_bitmap);
continue;
case RET_BCO: {
projects / ghc-hetmet.git / commitdiff