7127706: G1: re-enable survivors during the initial-mark pause
Summary: Re-enable survivors during the initial-mark pause. Afterwards, the concurrent marking threads have to scan them and mark everything reachable from them. The next GC will have to wait for the survivors to be scanned.
Reviewed-by: brutisso, johnc
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#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_INLINE_HPP
#define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_INLINE_HPP
inline HeapWord* G1OffsetTableContigSpace::allocate(size_t size) {
HeapWord* res = ContiguousSpace::allocate(size);
if (res != NULL) {
_offsets.alloc_block(res, size);
}
return res;
}
// Because of the requirement of keeping "_offsets" up to date with the
// allocations, we sequentialize these with a lock. Therefore, best if
// this is used for larger LAB allocations only.
inline HeapWord* G1OffsetTableContigSpace::par_allocate(size_t size) {
MutexLocker x(&_par_alloc_lock);
// Given that we take the lock no need to use par_allocate() here.
HeapWord* res = ContiguousSpace::allocate(size);
if (res != NULL) {
_offsets.alloc_block(res, size);
}
return res;
}
inline HeapWord* G1OffsetTableContigSpace::block_start(const void* p) {
return _offsets.block_start(p);
}
inline HeapWord*
G1OffsetTableContigSpace::block_start_const(const void* p) const {
return _offsets.block_start_const(p);
}
inline void HeapRegion::note_start_of_marking() {
init_top_at_conc_mark_count();
_next_marked_bytes = 0;
_next_top_at_mark_start = top();
}
inline void HeapRegion::note_end_of_marking() {
_prev_top_at_mark_start = _next_top_at_mark_start;
_prev_marked_bytes = _next_marked_bytes;
_next_marked_bytes = 0;
assert(_prev_marked_bytes <=
(size_t) pointer_delta(prev_top_at_mark_start(), bottom()) *
HeapWordSize, "invariant");
}
inline void HeapRegion::note_start_of_copying(bool during_initial_mark) {
if (is_survivor()) {
// This is how we always allocate survivors.
assert(_next_top_at_mark_start == bottom(), "invariant");
} else {
if (during_initial_mark) {
// During initial-mark we'll explicitly mark any objects on old
// regions that are pointed to by roots. Given that explicit
// marks only make sense under NTAMS it'd be nice if we could
// check that condition if we wanted to. Given that we don't
// know where the top of this region will end up, we simply set
// NTAMS to the end of the region so all marks will be below
// NTAMS. We'll set it to the actual top when we retire this region.
_next_top_at_mark_start = end();
} else {
// We could have re-used this old region as to-space over a
// couple of GCs since the start of the concurrent marking
// cycle. This means that [bottom,NTAMS) will contain objects
// copied up to and including initial-mark and [NTAMS, top)
// will contain objects copied during the concurrent marking cycle.
assert(top() >= _next_top_at_mark_start, "invariant");
}
}
}
inline void HeapRegion::note_end_of_copying(bool during_initial_mark) {
if (is_survivor()) {
// This is how we always allocate survivors.
assert(_next_top_at_mark_start == bottom(), "invariant");
} else {
if (during_initial_mark) {
// See the comment for note_start_of_copying() for the details
// on this.
assert(_next_top_at_mark_start == end(), "pre-condition");
_next_top_at_mark_start = top();
} else {
// See the comment for note_start_of_copying() for the details
// on this.
assert(top() >= _next_top_at_mark_start, "invariant");
}
}
}
#endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_INLINE_HPP