// This method assumes that from-space has live data and that
// any shrinkage of the young gen is limited by location of
// from-space.
size_t PSYoungGen::available_to_live() {
size_t delta_in_survivor = 0;
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t space_alignment = heap->intra_heap_alignment();
const size_t gen_alignment = heap->young_gen_alignment();
MutableSpace* space_shrinking = NULL;
if (from_space()->end() > to_space()->end()) {
space_shrinking = from_space();
} else {
space_shrinking = to_space();
}
// Include any space that is committed but not included in
// the survivor spaces.
assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
"Survivor space beyond high end");
size_t unused_committed = pointer_delta(virtual_space()->high(),
space_shrinking->end(), sizeof(char));
if (space_shrinking->is_empty()) {
// Don't let the space shrink to 0
assert(space_shrinking->capacity_in_bytes() >= space_alignment,
"Space is too small");
delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment;
} else {
delta_in_survivor = pointer_delta(space_shrinking->end(),
space_shrinking->top(),
sizeof(char));
}
size_t delta_in_bytes = unused_committed + delta_in_survivor;
delta_in_bytes = align_size_down(delta_in_bytes, gen_alignment);
return delta_in_bytes;
}
void PSYoungGen::swap_spaces() {
MutableSpace* s = from_space();
_from_space = to_space();
_to_space = s;
// Now update the decorators.
PSMarkSweepDecorator* md = from_mark_sweep();
_from_mark_sweep = to_mark_sweep();
_to_mark_sweep = md;
assert(from_mark_sweep()->space() == from_space(), "Sanity");
assert(to_mark_sweep()->space() == to_space(), "Sanity");
}
// This method assumes that from-space has live data and that
// any shrinkage of the young gen is limited by location of
// from-space.
size_t ASParNewGeneration::available_to_live() const {
#undef SHRINKS_AT_END_OF_EDEN
#ifdef SHRINKS_AT_END_OF_EDEN
size_t delta_in_survivor = 0;
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t space_alignment = heap->intra_heap_alignment();
const size_t gen_alignment = heap->object_heap_alignment();
MutableSpace* space_shrinking = NULL;
if (from_space()->end() > to_space()->end()) {
space_shrinking = from_space();
} else {
space_shrinking = to_space();
}
// Include any space that is committed but not included in
// the survivor spaces.
assert(((HeapWord*)virtual_space()->high()) >= space_shrinking->end(),
"Survivor space beyond high end");
size_t unused_committed = pointer_delta(virtual_space()->high(),
space_shrinking->end(), sizeof(char));
if (space_shrinking->is_empty()) {
// Don't let the space shrink to 0
assert(space_shrinking->capacity_in_bytes() >= space_alignment,
"Space is too small");
delta_in_survivor = space_shrinking->capacity_in_bytes() - space_alignment;
} else {
delta_in_survivor = pointer_delta(space_shrinking->end(),
space_shrinking->top(),
sizeof(char));
}
size_t delta_in_bytes = unused_committed + delta_in_survivor;
delta_in_bytes = align_size_down(delta_in_bytes, gen_alignment);
return delta_in_bytes;
#else
// The only space available for shrinking is in to-space if it
// is above from-space.
if (to()->bottom() > from()->bottom()) {
const size_t alignment = os::vm_page_size();
if (to()->capacity() < alignment) {
return 0;
} else {
return to()->capacity() - alignment;
}
} else {
return 0;
}
#endif
}
void PSYoungGen::space_invariants() {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t alignment = heap->intra_heap_alignment();
// Currently, our eden size cannot shrink to zero
guarantee(eden_space()->capacity_in_bytes() >= alignment, "eden too small");
guarantee(from_space()->capacity_in_bytes() >= alignment, "from too small");
guarantee(to_space()->capacity_in_bytes() >= alignment, "to too small");
// Relationship of spaces to each other
char* eden_start = (char*)eden_space()->bottom();
char* eden_end = (char*)eden_space()->end();
char* from_start = (char*)from_space()->bottom();
char* from_end = (char*)from_space()->end();
char* to_start = (char*)to_space()->bottom();
char* to_end = (char*)to_space()->end();
guarantee(eden_start >= virtual_space()->low(), "eden bottom");
guarantee(eden_start < eden_end, "eden space consistency");
guarantee(from_start < from_end, "from space consistency");
guarantee(to_start < to_end, "to space consistency");
// Check whether from space is below to space
if (from_start < to_start) {
// Eden, from, to
guarantee(eden_end <= from_start, "eden/from boundary");
guarantee(from_end <= to_start, "from/to boundary");
guarantee(to_end <= virtual_space()->high(), "to end");
} else {
// Eden, to, from
guarantee(eden_end <= to_start, "eden/to boundary");
guarantee(to_end <= from_start, "to/from boundary");
guarantee(from_end <= virtual_space()->high(), "from end");
}
// More checks that the virtual space is consistent with the spaces
assert(virtual_space()->committed_size() >=
(eden_space()->capacity_in_bytes() +
to_space()->capacity_in_bytes() +
from_space()->capacity_in_bytes()), "Committed size is inconsistent");
assert(virtual_space()->committed_size() <= virtual_space()->reserved_size(),
"Space invariant");
char* eden_top = (char*)eden_space()->top();
char* from_top = (char*)from_space()->top();
char* to_top = (char*)to_space()->top();
assert(eden_top <= virtual_space()->high(), "eden top");
assert(from_top <= virtual_space()->high(), "from top");
assert(to_top <= virtual_space()->high(), "to top");
virtual_space()->verify();
}
void PSYoungGen::set_space_boundaries(size_t eden_size, size_t survivor_size) {
assert(eden_size < virtual_space()->committed_size(), "just checking");
assert(eden_size > 0 && survivor_size > 0, "just checking");
// Initial layout is Eden, to, from. After swapping survivor spaces,
// that leaves us with Eden, from, to, which is step one in our two
// step resize-with-live-data procedure.
char *eden_start = virtual_space()->low();
char *to_start = eden_start + eden_size;
char *from_start = to_start + survivor_size;
char *from_end = from_start + survivor_size;
assert(from_end == virtual_space()->high(), "just checking");
assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
assert(is_object_aligned((intptr_t)to_start), "checking alignment");
assert(is_object_aligned((intptr_t)from_start), "checking alignment");
MemRegion eden_mr((HeapWord*)eden_start, (HeapWord*)to_start);
MemRegion to_mr ((HeapWord*)to_start, (HeapWord*)from_start);
MemRegion from_mr((HeapWord*)from_start, (HeapWord*)from_end);
eden_space()->initialize(eden_mr, true, ZapUnusedHeapArea);
to_space()->initialize(to_mr , true, ZapUnusedHeapArea);
from_space()->initialize(from_mr, true, ZapUnusedHeapArea);
}
// This method currently does not expect to expand into eden (i.e.,
// the virtual space boundaries is expected to be consistent
// with the eden boundaries..
void PSYoungGen::post_resize() {
assert_locked_or_safepoint(Heap_lock);
assert((eden_space()->bottom() < to_space()->bottom()) &&
(eden_space()->bottom() < from_space()->bottom()),
"Eden is assumed to be below the survivor spaces");
MemRegion cmr((HeapWord*)virtual_space()->low(),
(HeapWord*)virtual_space()->high());
Universe::heap()->barrier_set()->resize_covered_region(cmr);
space_invariants();
}
void PSYoungGen::reset_survivors_after_shrink() {
_reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(),
(HeapWord*)virtual_space()->high_boundary());
PSScavenge::reference_processor()->set_span(_reserved);
MutableSpace* space_shrinking = NULL;
if (from_space()->end() > to_space()->end()) {
space_shrinking = from_space();
} else {
space_shrinking = to_space();
}
HeapWord* new_end = (HeapWord*)virtual_space()->high();
assert(new_end >= space_shrinking->bottom(), "Shrink was too large");
// Was there a shrink of the survivor space?
if (new_end < space_shrinking->end()) {
MemRegion mr(space_shrinking->bottom(), new_end);
space_shrinking->initialize(mr,
SpaceDecorator::DontClear,
SpaceDecorator::Mangle);
}
}
void PSYoungGen::print_on(outputStream* st) const {
st->print(" %-15s", "PSYoungGen");
if (PrintGCDetails && Verbose) {
st->print(" total " SIZE_FORMAT ", used " SIZE_FORMAT,
capacity_in_bytes(), used_in_bytes());
} else {
st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
capacity_in_bytes()/K, used_in_bytes()/K);
}
virtual_space()->print_space_boundaries_on(st);
st->print(" eden"); eden_space()->print_on(st);
st->print(" from"); from_space()->print_on(st);
st->print(" to "); to_space()->print_on(st);
}
PSHeapSummary ParallelScavengeHeap::create_ps_heap_summary() {
PSOldGen* old = old_gen();
HeapWord* old_committed_end = (HeapWord*)old->virtual_space()->committed_high_addr();
VirtualSpaceSummary old_summary(old->reserved().start(), old_committed_end, old->reserved().end());
SpaceSummary old_space(old->reserved().start(), old_committed_end, old->used_in_bytes());
PSYoungGen* young = young_gen();
VirtualSpaceSummary young_summary(young->reserved().start(),
(HeapWord*)young->virtual_space()->committed_high_addr(), young->reserved().end());
MutableSpace* eden = young_gen()->eden_space();
SpaceSummary eden_space(eden->bottom(), eden->end(), eden->used_in_bytes());
MutableSpace* from = young_gen()->from_space();
SpaceSummary from_space(from->bottom(), from->end(), from->used_in_bytes());
MutableSpace* to = young_gen()->to_space();
SpaceSummary to_space(to->bottom(), to->end(), to->used_in_bytes());
VirtualSpaceSummary heap_summary = create_heap_space_summary();
return PSHeapSummary(heap_summary, used(), old_summary, old_space, young_summary, eden_space, from_space, to_space);
}
void PSYoungGen::object_iterate(ObjectClosure* blk) {
eden_space()->object_iterate(blk);
from_space()->object_iterate(blk);
to_space()->object_iterate(blk);
}
size_t PSYoungGen::free_in_words() const {
return eden_space()->free_in_words()
+ from_space()->free_in_words(); // to_space() is only used during scavenge
}
"from start moved to the right");
guarantee((HeapWord*)from_end >= from_space()->top(),
"from end moved into live data");
assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
assert(is_object_aligned((intptr_t)from_start), "checking alignment");
assert(is_object_aligned((intptr_t)to_start), "checking alignment");
MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
// Let's make sure the call to initialize doesn't reset "top"!
DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
// For PrintAdaptiveSizePolicy block below
size_t old_from = from_space()->capacity_in_bytes();
size_t old_to = to_space()->capacity_in_bytes();
if (ZapUnusedHeapArea) {
// NUMA is a special case because a numa space is not mangled
// in order to not prematurely bind its address to memory to
// the wrong memory (i.e., don't want the GC thread to first
// touch the memory). The survivor spaces are not numa
// spaces and are mangled.
if (UseNUMA) {
if (eden_from_to_order) {
mangle_survivors(from_space(), fromMR, to_space(), toMR);
} else {
mangle_survivors(to_space(), toMR, from_space(), fromMR);
}
}
void PSYoungGen::resize_spaces(size_t requested_eden_size,
size_t requested_survivor_size) {
assert(UseAdaptiveSizePolicy, "sanity check");
assert(requested_eden_size > 0 && requested_survivor_size > 0,
"just checking");
// We require eden and to space to be empty
if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
return;
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
SIZE_FORMAT
", requested_survivor_size: " SIZE_FORMAT ")",
requested_eden_size, requested_survivor_size);
gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
eden_space()->bottom(),
eden_space()->end(),
pointer_delta(eden_space()->end(),
eden_space()->bottom(),
sizeof(char)));
gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
from_space()->bottom(),
from_space()->end(),
pointer_delta(from_space()->end(),
from_space()->bottom(),
sizeof(char)));
gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
to_space()->bottom(),
to_space()->end(),
pointer_delta( to_space()->end(),
to_space()->bottom(),
sizeof(char)));
}
// There's nothing to do if the new sizes are the same as the current
if (requested_survivor_size == to_space()->capacity_in_bytes() &&
requested_survivor_size == from_space()->capacity_in_bytes() &&
requested_eden_size == eden_space()->capacity_in_bytes()) {
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" capacities are the right sizes, returning");
}
return;
}
char* eden_start = (char*)eden_space()->bottom();
char* eden_end = (char*)eden_space()->end();
char* from_start = (char*)from_space()->bottom();
char* from_end = (char*)from_space()->end();
char* to_start = (char*)to_space()->bottom();
char* to_end = (char*)to_space()->end();
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t alignment = heap->intra_heap_alignment();
const bool maintain_minimum =
(requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
bool eden_from_to_order = from_start < to_start;
// Check whether from space is below to space
if (eden_from_to_order) {
// Eden, from, to
eden_from_to_order = true;
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" Eden, from, to:");
}
// Set eden
// "requested_eden_size" is a goal for the size of eden
// and may not be attainable. "eden_size" below is
// calculated based on the location of from-space and
// the goal for the size of eden. from-space is
// fixed in place because it contains live data.
// The calculation is done this way to avoid 32bit
// overflow (i.e., eden_start + requested_eden_size
// may too large for representation in 32bits).
size_t eden_size;
if (maintain_minimum) {
// Only make eden larger than the requested size if
// the minimum size of the generation has to be maintained.
// This could be done in general but policy at a higher
// level is determining a requested size for eden and that
// should be honored unless there is a fundamental reason.
eden_size = pointer_delta(from_start,
eden_start,
sizeof(char));
} else {
eden_size = MIN2(requested_eden_size,
pointer_delta(from_start, eden_start, sizeof(char)));
}
eden_end = eden_start + eden_size;
assert(eden_end >= eden_start, "addition overflowed");
// To may resize into from space as long as it is clear of live data.
// From space must remain page aligned, though, so we need to do some
// extra calculations.
// First calculate an optimal to-space
to_end = (char*)virtual_space()->high();
to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
sizeof(char));
// Does the optimal to-space overlap from-space?
if (to_start < (char*)from_space()->end()) {
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// Calculate the minimum offset possible for from_end
size_t from_size = pointer_delta(from_space()->top(), from_start, sizeof(char));
// Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
if (from_size == 0) {
from_size = alignment;
} else {
from_size = align_size_up(from_size, alignment);
}
from_end = from_start + from_size;
assert(from_end > from_start, "addition overflow or from_size problem");
guarantee(from_end <= (char*)from_space()->end(), "from_end moved to the right");
// Now update to_start with the new from_end
to_start = MAX2(from_end, to_start);
}
guarantee(to_start != to_end, "to space is zero sized");
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" [eden_start .. eden_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
eden_start,
eden_end,
pointer_delta(eden_end, eden_start, sizeof(char)));
gclog_or_tty->print_cr(" [from_start .. from_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
from_start,
from_end,
pointer_delta(from_end, from_start, sizeof(char)));
gclog_or_tty->print_cr(" [ to_start .. to_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
to_start,
to_end,
pointer_delta( to_end, to_start, sizeof(char)));
}
} else {
// Eden, to, from
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" Eden, to, from:");
}
// To space gets priority over eden resizing. Note that we position
// to space as if we were able to resize from space, even though from
// space is not modified.
// Giving eden priority was tried and gave poorer performance.
to_end = (char*)pointer_delta(virtual_space()->high(),
(char*)requested_survivor_size,
sizeof(char));
to_end = MIN2(to_end, from_start);
to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
sizeof(char));
// if the space sizes are to be increased by several times then
// 'to_start' will point beyond the young generation. In this case
// 'to_start' should be adjusted.
to_start = MAX2(to_start, eden_start + alignment);
// Compute how big eden can be, then adjust end.
// See comments above on calculating eden_end.
size_t eden_size;
if (maintain_minimum) {
eden_size = pointer_delta(to_start, eden_start, sizeof(char));
} else {
eden_size = MIN2(requested_eden_size,
pointer_delta(to_start, eden_start, sizeof(char)));
}
eden_end = eden_start + eden_size;
assert(eden_end >= eden_start, "addition overflowed");
// Could choose to not let eden shrink
// to_start = MAX2(to_start, eden_end);
// Don't let eden shrink down to 0 or less.
eden_end = MAX2(eden_end, eden_start + alignment);
to_start = MAX2(to_start, eden_end);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" [eden_start .. eden_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
eden_start,
eden_end,
pointer_delta(eden_end, eden_start, sizeof(char)));
gclog_or_tty->print_cr(" [ to_start .. to_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
to_start,
to_end,
pointer_delta( to_end, to_start, sizeof(char)));
gclog_or_tty->print_cr(" [from_start .. from_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
from_start,
from_end,
pointer_delta(from_end, from_start, sizeof(char)));
}
}
guarantee((HeapWord*)from_start <= from_space()->bottom(),
"from start moved to the right");
guarantee((HeapWord*)from_end >= from_space()->top(),
"from end moved into live data");
assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
assert(is_object_aligned((intptr_t)from_start), "checking alignment");
assert(is_object_aligned((intptr_t)to_start), "checking alignment");
MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
// Let's make sure the call to initialize doesn't reset "top"!
HeapWord* old_from_top = from_space()->top();
// For PrintAdaptiveSizePolicy block below
size_t old_from = from_space()->capacity_in_bytes();
size_t old_to = to_space()->capacity_in_bytes();
if (ZapUnusedHeapArea) {
// NUMA is a special case because a numa space is not mangled
// in order to not prematurely bind its address to memory to
// the wrong memory (i.e., don't want the GC thread to first
// touch the memory). The survivor spaces are not numa
// spaces and are mangled.
if (UseNUMA) {
if (eden_from_to_order) {
mangle_survivors(from_space(), fromMR, to_space(), toMR);
} else {
mangle_survivors(to_space(), toMR, from_space(), fromMR);
}
}
// If not mangling the spaces, do some checking to verify that
// the spaces are already mangled.
// The spaces should be correctly mangled at this point so
// do some checking here. Note that they are not being mangled
// in the calls to initialize().
// Must check mangling before the spaces are reshaped. Otherwise,
// the bottom or end of one space may have moved into an area
// covered by another space and a failure of the check may
// not correctly indicate which space is not properly mangled.
HeapWord* limit = (HeapWord*) virtual_space()->high();
eden_space()->check_mangled_unused_area(limit);
from_space()->check_mangled_unused_area(limit);
to_space()->check_mangled_unused_area(limit);
}
// When an existing space is being initialized, it is not
// mangled because the space has been previously mangled.
eden_space()->initialize(edenMR,
SpaceDecorator::Clear,
SpaceDecorator::DontMangle);
to_space()->initialize(toMR,
SpaceDecorator::Clear,
SpaceDecorator::DontMangle);
from_space()->initialize(fromMR,
SpaceDecorator::DontClear,
SpaceDecorator::DontMangle);
assert(from_space()->top() == old_from_top, "from top changed!");
if (PrintAdaptiveSizePolicy) {
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
"collection: %d "
"(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
"(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
heap->total_collections(),
old_from, old_to,
from_space()->capacity_in_bytes(),
to_space()->capacity_in_bytes());
gclog_or_tty->cr();
}
}
void PSYoungGen::verify(bool allow_dirty) {
eden_space()->verify(allow_dirty);
from_space()->verify(allow_dirty);
to_space()->verify(allow_dirty);
}
void ASPSYoungGen::resize_spaces(size_t requested_eden_size,
size_t requested_survivor_size) {
assert(UseAdaptiveSizePolicy, "sanity check");
assert(requested_eden_size > 0 && requested_survivor_size > 0,
"just checking");
space_invariants();
// We require eden and to space to be empty
if ((!eden_space()->is_empty()) || (!to_space()->is_empty())) {
return;
}
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("PSYoungGen::resize_spaces(requested_eden_size: "
SIZE_FORMAT
", requested_survivor_size: " SIZE_FORMAT ")",
requested_eden_size, requested_survivor_size);
gclog_or_tty->print_cr(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
eden_space()->bottom(),
eden_space()->end(),
pointer_delta(eden_space()->end(),
eden_space()->bottom(),
sizeof(char)));
gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
from_space()->bottom(),
from_space()->end(),
pointer_delta(from_space()->end(),
from_space()->bottom(),
sizeof(char)));
gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
to_space()->bottom(),
to_space()->end(),
pointer_delta( to_space()->end(),
to_space()->bottom(),
sizeof(char)));
}
// There's nothing to do if the new sizes are the same as the current
if (requested_survivor_size == to_space()->capacity_in_bytes() &&
requested_survivor_size == from_space()->capacity_in_bytes() &&
requested_eden_size == eden_space()->capacity_in_bytes()) {
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" capacities are the right sizes, returning");
}
return;
}
char* eden_start = (char*)virtual_space()->low();
char* eden_end = (char*)eden_space()->end();
char* from_start = (char*)from_space()->bottom();
char* from_end = (char*)from_space()->end();
char* to_start = (char*)to_space()->bottom();
char* to_end = (char*)to_space()->end();
assert(eden_start < from_start, "Cannot push into from_space");
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t alignment = heap->intra_heap_alignment();
const bool maintain_minimum =
(requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
bool eden_from_to_order = from_start < to_start;
// Check whether from space is below to space
if (eden_from_to_order) {
// Eden, from, to
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" Eden, from, to:");
}
// Set eden
// "requested_eden_size" is a goal for the size of eden
// and may not be attainable. "eden_size" below is
// calculated based on the location of from-space and
// the goal for the size of eden. from-space is
// fixed in place because it contains live data.
// The calculation is done this way to avoid 32bit
// overflow (i.e., eden_start + requested_eden_size
// may too large for representation in 32bits).
size_t eden_size;
if (maintain_minimum) {
// Only make eden larger than the requested size if
// the minimum size of the generation has to be maintained.
// This could be done in general but policy at a higher
// level is determining a requested size for eden and that
// should be honored unless there is a fundamental reason.
eden_size = pointer_delta(from_start,
eden_start,
sizeof(char));
} else {
eden_size = MIN2(requested_eden_size,
pointer_delta(from_start, eden_start, sizeof(char)));
}
eden_end = eden_start + eden_size;
assert(eden_end >= eden_start, "addition overflowed")
// To may resize into from space as long as it is clear of live data.
// From space must remain page aligned, though, so we need to do some
// extra calculations.
// First calculate an optimal to-space
to_end = (char*)virtual_space()->high();
to_start = (char*)pointer_delta(to_end,
(char*)requested_survivor_size,
sizeof(char));
// Does the optimal to-space overlap from-space?
if (to_start < (char*)from_space()->end()) {
assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
// Calculate the minimum offset possible for from_end
size_t from_size =
pointer_delta(from_space()->top(), from_start, sizeof(char));
// Should we be in this method if from_space is empty? Why not the set_space method? FIX ME!
if (from_size == 0) {
from_size = alignment;
} else {
from_size = align_size_up(from_size, alignment);
}
from_end = from_start + from_size;
assert(from_end > from_start, "addition overflow or from_size problem");
guarantee(from_end <= (char*)from_space()->end(),
"from_end moved to the right");
// Now update to_start with the new from_end
to_start = MAX2(from_end, to_start);
}
guarantee(to_start != to_end, "to space is zero sized");
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" [eden_start .. eden_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
eden_start,
eden_end,
pointer_delta(eden_end, eden_start, sizeof(char)));
gclog_or_tty->print_cr(" [from_start .. from_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
from_start,
from_end,
pointer_delta(from_end, from_start, sizeof(char)));
gclog_or_tty->print_cr(" [ to_start .. to_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
to_start,
to_end,
pointer_delta( to_end, to_start, sizeof(char)));
}
} else {
// Eden, to, from
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" Eden, to, from:");
}
// To space gets priority over eden resizing. Note that we position
// to space as if we were able to resize from space, even though from
// space is not modified.
// Giving eden priority was tried and gave poorer performance.
to_end = (char*)pointer_delta(virtual_space()->high(),
(char*)requested_survivor_size,
sizeof(char));
to_end = MIN2(to_end, from_start);
to_start = (char*)pointer_delta(to_end, (char*)requested_survivor_size,
sizeof(char));
// if the space sizes are to be increased by several times then
// 'to_start' will point beyond the young generation. In this case
// 'to_start' should be adjusted.
to_start = MAX2(to_start, eden_start + alignment);
// Compute how big eden can be, then adjust end.
// See comments above on calculating eden_end.
size_t eden_size;
if (maintain_minimum) {
eden_size = pointer_delta(to_start, eden_start, sizeof(char));
} else {
eden_size = MIN2(requested_eden_size,
pointer_delta(to_start, eden_start, sizeof(char)));
}
eden_end = eden_start + eden_size;
assert(eden_end >= eden_start, "addition overflowed")
// Don't let eden shrink down to 0 or less.
eden_end = MAX2(eden_end, eden_start + alignment);
to_start = MAX2(to_start, eden_end);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" [eden_start .. eden_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
eden_start,
eden_end,
pointer_delta(eden_end, eden_start, sizeof(char)));
gclog_or_tty->print_cr(" [ to_start .. to_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
to_start,
to_end,
pointer_delta( to_end, to_start, sizeof(char)));
gclog_or_tty->print_cr(" [from_start .. from_end): "
"[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT,
from_start,
from_end,
pointer_delta(from_end, from_start, sizeof(char)));
}
}
guarantee((HeapWord*)from_start <= from_space()->bottom(),
"from start moved to the right");
guarantee((HeapWord*)from_end >= from_space()->top(),
"from end moved into live data");
assert(is_object_aligned((intptr_t)eden_start), "checking alignment");
assert(is_object_aligned((intptr_t)from_start), "checking alignment");
assert(is_object_aligned((intptr_t)to_start), "checking alignment");
MemRegion edenMR((HeapWord*)eden_start, (HeapWord*)eden_end);
MemRegion toMR ((HeapWord*)to_start, (HeapWord*)to_end);
MemRegion fromMR((HeapWord*)from_start, (HeapWord*)from_end);
// Let's make sure the call to initialize doesn't reset "top"!
DEBUG_ONLY(HeapWord* old_from_top = from_space()->top();)
void PSYoungGen::verify() {
eden_space()->verify();
from_space()->verify();
to_space()->verify();
}
void PSYoungGen::record_spaces_top() {
assert(ZapUnusedHeapArea, "Not mangling unused space");
eden_space()->set_top_for_allocations();
from_space()->set_top_for_allocations();
to_space()->set_top_for_allocations();
}
size_t PSYoungGen::used_in_bytes() const {
return eden_space()->used_in_bytes()
+ from_space()->used_in_bytes(); // to_space() is only used during scavenge
}
