StgInt
newSpark (StgRegTable *reg, StgClosure *p)
{
Capability *cap = regTableToCapability(reg);
SparkPool *pool = cap->sparks;
/* I am not sure whether this is the right thing to do.
* Maybe it is better to exploit the tag information
* instead of throwing it away?
*/
p = UNTAG_CLOSURE(p);
if (closure_SHOULD_SPARK(p)) {
pushWSDeque(pool,p);
cap->sparks_created++;
} else {
cap->sparks_dud++;
}
return 1;
}
StgPtr
todo_block_full (uint32_t size, gen_workspace *ws)
{
bool urgent_to_push, can_extend;
StgPtr p;
bdescr *bd;
// todo_free has been pre-incremented by Evac.c:alloc_for_copy(). We
// are expected to leave it bumped when we've finished here.
ws->todo_free -= size;
bd = ws->todo_bd;
ASSERT(bd != NULL);
ASSERT(bd->link == NULL);
ASSERT(bd->gen == ws->gen);
// We intentionally set ws->todo_lim lower than the full size of
// the block, so that we can push out some work to the global list
// and get the parallel threads working as soon as possible.
//
// So when ws->todo_lim is reached, we end up here and have to
// decide whether it's worth pushing out the work we have or not.
// If we have enough room in the block to evacuate the current
// object, and it's not urgent to push this work, then we just
// extend the limit and keep going. Where "urgent" is defined as:
// the global pool is empty, and there's enough work in this block
// to make it worth pushing.
//
urgent_to_push =
looksEmptyWSDeque(ws->todo_q) &&
(ws->todo_free - bd->u.scan >= WORK_UNIT_WORDS / 2);
// We can extend the limit for the current block if there's enough
// room for the current object, *and* we're not into the second or
// subsequent block of a large block (see Note [big objects]).
can_extend =
ws->todo_free + size <= bd->start + bd->blocks * BLOCK_SIZE_W
&& ws->todo_free < ws->todo_bd->start + BLOCK_SIZE_W;
if (!urgent_to_push && can_extend)
{
ws->todo_lim = stg_min(bd->start + bd->blocks * BLOCK_SIZE_W,
ws->todo_lim + stg_max(WORK_UNIT_WORDS,size));
debugTrace(DEBUG_gc, "increasing limit for %p to %p",
bd->start, ws->todo_lim);
p = ws->todo_free;
ws->todo_free += size;
return p;
}
gct->copied += ws->todo_free - bd->free;
bd->free = ws->todo_free;
ASSERT(bd->u.scan >= bd->start && bd->u.scan <= bd->free);
// If this block is not the scan block, we want to push it out and
// make room for a new todo block.
if (bd != gct->scan_bd)
{
// If this block does not have enough space to allocate the
// current object, but it also doesn't have any work to push, then
// push it on to the scanned list.
if (bd->u.scan == bd->free)
{
if (bd->free == bd->start) {
// Normally the block would not be empty, because then
// there would be enough room to copy the current
// object. However, if the object we're copying is
// larger than a block, then we might have an empty
// block here.
freeGroup_sync(bd);
} else {
push_scanned_block(bd, ws);
}
}
// Otherwise, push this block out to the global list.
else
{
DEBUG_ONLY( generation *gen );
DEBUG_ONLY( gen = ws->gen );
debugTrace(DEBUG_gc, "push todo block %p (%ld words), step %d, todo_q: %ld",
bd->start, (unsigned long)(bd->free - bd->u.scan),
gen->no, dequeElements(ws->todo_q));
if (!pushWSDeque(ws->todo_q, bd)) {
bd->link = ws->todo_overflow;
ws->todo_overflow = bd;
ws->n_todo_overflow++;
}
}
}
ws->todo_bd = NULL;
ws->todo_free = NULL;
ws->todo_lim = NULL;
alloc_todo_block(ws, size);
p = ws->todo_free;
ws->todo_free += size;
return p;
}
