size_t ASPSOldGen::available_for_contraction() {
size_t uncommitted_bytes = virtual_space()->uncommitted_size();
if (uncommitted_bytes != 0) {
return uncommitted_bytes;
}
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t gen_alignment = heap->old_gen_alignment();
PSAdaptiveSizePolicy* policy = heap->size_policy();
const size_t working_size =
used_in_bytes() + (size_t) policy->avg_promoted()->padded_average();
const size_t working_aligned = align_size_up(working_size, gen_alignment);
const size_t working_or_min = MAX2(working_aligned, min_gen_size());
if (working_or_min > reserved().byte_size()) {
// If the used or minimum gen size (aligned up) is greater
// than the total reserved size, then the space available
// for contraction should (after proper alignment) be 0
return 0;
}
const size_t max_contraction =
reserved().byte_size() - working_or_min;
// Use the "increment" fraction instead of the "decrement" fraction
// to allow the other gen to expand more aggressively. The
// "decrement" fraction is conservative because its intent is to
// only reduce the footprint.
size_t result = policy->promo_increment_aligned_down(max_contraction);
// Also adjust for inter-generational alignment
size_t result_aligned = align_size_down(result, gen_alignment);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("\nASPSOldGen::available_for_contraction:"
" %d K / 0x%x", result_aligned/K, result_aligned);
gclog_or_tty->print_cr(" reserved().byte_size() %d K / 0x%x ",
reserved().byte_size()/K, reserved().byte_size());
size_t working_promoted = (size_t) policy->avg_promoted()->padded_average();
gclog_or_tty->print_cr(" padded promoted %d K / 0x%x",
working_promoted/K, working_promoted);
gclog_or_tty->print_cr(" used %d K / 0x%x",
used_in_bytes()/K, used_in_bytes());
gclog_or_tty->print_cr(" min_gen_size() %d K / 0x%x",
min_gen_size()/K, min_gen_size());
gclog_or_tty->print_cr(" max_contraction %d K / 0x%x",
max_contraction/K, max_contraction);
gclog_or_tty->print_cr(" without alignment %d K / 0x%x",
policy->promo_increment(max_contraction)/K,
policy->promo_increment(max_contraction));
gclog_or_tty->print_cr(" alignment 0x%x", gen_alignment);
}
assert(result_aligned <= max_contraction, "arithmetic is wrong");
return result_aligned;
}
// Return the number of bytes the young gen is willing give up.
//
// Future implementations could check the survivors and if to_space is in the
// right place (below from_space), take a chunk from to_space.
size_t ASPSYoungGen::available_for_contraction() {
size_t uncommitted_bytes = virtual_space()->uncommitted_size();
if (uncommitted_bytes != 0) {
return uncommitted_bytes;
}
if (eden_space()->is_empty()) {
// Respect the minimum size for eden and for the young gen as a whole.
ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
const size_t eden_alignment = heap->intra_heap_alignment();
const size_t gen_alignment = heap->young_gen_alignment();
assert(eden_space()->capacity_in_bytes() >= eden_alignment,
"Alignment is wrong");
size_t eden_avail = eden_space()->capacity_in_bytes() - eden_alignment;
eden_avail = align_size_down(eden_avail, gen_alignment);
assert(virtual_space()->committed_size() >= min_gen_size(),
"minimum gen size is wrong");
size_t gen_avail = virtual_space()->committed_size() - min_gen_size();
assert(virtual_space()->is_aligned(gen_avail), "not aligned");
const size_t max_contraction = MIN2(eden_avail, gen_avail);
// See comment for ASPSOldGen::available_for_contraction()
// for reasons the "increment" fraction is used.
PSAdaptiveSizePolicy* policy = heap->size_policy();
size_t result = policy->eden_increment_aligned_down(max_contraction);
size_t result_aligned = align_size_down(result, gen_alignment);
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("ASPSYoungGen::available_for_contraction: %d K",
result_aligned/K);
gclog_or_tty->print_cr(" max_contraction %d K", max_contraction/K);
gclog_or_tty->print_cr(" eden_avail %d K", eden_avail/K);
gclog_or_tty->print_cr(" gen_avail %d K", gen_avail/K);
}
return result_aligned;
}
return 0;
}
void PSYoungGen::resize(size_t eden_size, size_t survivor_size) {
// Resize the generation if needed. If the generation resize
// reports false, do not attempt to resize the spaces.
if (resize_generation(eden_size, survivor_size)) {
// Then we lay out the spaces inside the generation
resize_spaces(eden_size, survivor_size);
space_invariants();
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("Young generation size: "
"desired eden: " SIZE_FORMAT " survivor: " SIZE_FORMAT
" used: " SIZE_FORMAT " capacity: " SIZE_FORMAT
" gen limits: " SIZE_FORMAT " / " SIZE_FORMAT,
eden_size, survivor_size, used_in_bytes(), capacity_in_bytes(),
_max_gen_size, min_gen_size());
}
}
}
size_t PSYoungGen::available_to_min_gen() {
assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
return virtual_space()->committed_size() - min_gen_size();
}
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();
}
}
bool PSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
const size_t alignment = virtual_space()->alignment();
size_t orig_size = virtual_space()->committed_size();
bool size_changed = false;
// There used to be this guarantee there.
// guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments");
// Code below forces this requirement. In addition the desired eden
// size and disired survivor sizes are desired goals and may
// exceed the total generation size.
assert(min_gen_size() <= orig_size && orig_size <= max_size(), "just checking");
// Adjust new generation size
const size_t eden_plus_survivors =
align_size_up(eden_size + 2 * survivor_size, alignment);
size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_size()),
min_gen_size());
assert(desired_size <= max_size(), "just checking");
if (desired_size > orig_size) {
// Grow the generation
size_t change = desired_size - orig_size;
assert(change % alignment == 0, "just checking");
HeapWord* prev_high = (HeapWord*) virtual_space()->high();
if (!virtual_space()->expand_by(change)) {
return false; // Error if we fail to resize!
}
if (ZapUnusedHeapArea) {
// Mangle newly committed space immediately because it
// can be done here more simply that after the new
// spaces have been computed.
HeapWord* new_high = (HeapWord*) virtual_space()->high();
MemRegion mangle_region(prev_high, new_high);
SpaceMangler::mangle_region(mangle_region);
}
size_changed = true;
} else if (desired_size < orig_size) {
size_t desired_change = orig_size - desired_size;
assert(desired_change % alignment == 0, "just checking");
desired_change = limit_gen_shrink(desired_change);
if (desired_change > 0) {
virtual_space()->shrink_by(desired_change);
reset_survivors_after_shrink();
size_changed = true;
}
} else {
if (Verbose && PrintGC) {
if (orig_size == gen_size_limit()) {
gclog_or_tty->print_cr("PSYoung generation size at maximum: "
SIZE_FORMAT "K", orig_size/K);
} else if (orig_size == min_gen_size()) {
gclog_or_tty->print_cr("PSYoung generation size at minium: "
SIZE_FORMAT "K", orig_size/K);
}
}
}
if (size_changed) {
post_resize();
if (Verbose && PrintGC) {
size_t current_size = virtual_space()->committed_size();
gclog_or_tty->print_cr("PSYoung generation size changed: "
SIZE_FORMAT "K->" SIZE_FORMAT "K",
orig_size/K, current_size/K);
}
}
guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
virtual_space()->committed_size() == max_size(), "Sanity");
return true;
}
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();)
// Similar to PSYoungGen::resize_generation() but
// allows sum of eden_size and 2 * survivor_size to exceed _max_gen_size
// expands at the low end of the virtual space
// moves the boundary between the generations in order to expand
// some additional diagnostics
// If no additional changes are required, this can be deleted
// and the changes factored back into PSYoungGen::resize_generation().
bool ASPSYoungGen::resize_generation(size_t eden_size, size_t survivor_size) {
const size_t alignment = virtual_space()->alignment();
size_t orig_size = virtual_space()->committed_size();
bool size_changed = false;
// There used to be a guarantee here that
// (eden_size + 2*survivor_size) <= _max_gen_size
// This requirement is enforced by the calculation of desired_size
// below. It may not be true on entry since the size of the
// eden_size is no bounded by the generation size.
assert(max_size() == reserved().byte_size(), "max gen size problem?");
assert(min_gen_size() <= orig_size && orig_size <= max_size(),
"just checking");
// Adjust new generation size
const size_t eden_plus_survivors =
align_size_up(eden_size + 2 * survivor_size, alignment);
size_t desired_size = MAX2(MIN2(eden_plus_survivors, gen_size_limit()),
min_gen_size());
assert(desired_size <= gen_size_limit(), "just checking");
if (desired_size > orig_size) {
// Grow the generation
size_t change = desired_size - orig_size;
HeapWord* prev_low = (HeapWord*) virtual_space()->low();
if (!virtual_space()->expand_by(change)) {
return false;
}
if (ZapUnusedHeapArea) {
// Mangle newly committed space immediately because it
// can be done here more simply that after the new
// spaces have been computed.
HeapWord* new_low = (HeapWord*) virtual_space()->low();
assert(new_low < prev_low, "Did not grow");
MemRegion mangle_region(new_low, prev_low);
SpaceMangler::mangle_region(mangle_region);
}
size_changed = true;
} else if (desired_size < orig_size) {
size_t desired_change = orig_size - desired_size;
// How much is available for shrinking.
size_t available_bytes = limit_gen_shrink(desired_change);
size_t change = MIN2(desired_change, available_bytes);
virtual_space()->shrink_by(change);
size_changed = true;
} else {
if (Verbose && PrintGC) {
if (orig_size == gen_size_limit()) {
gclog_or_tty->print_cr("ASPSYoung generation size at maximum: "
SIZE_FORMAT "K", orig_size/K);
} else if (orig_size == min_gen_size()) {
gclog_or_tty->print_cr("ASPSYoung generation size at minium: "
SIZE_FORMAT "K", orig_size/K);
}
}
}
if (size_changed) {
reset_after_change();
if (Verbose && PrintGC) {
size_t current_size = virtual_space()->committed_size();
gclog_or_tty->print_cr("ASPSYoung generation size changed: "
SIZE_FORMAT "K->" SIZE_FORMAT "K",
orig_size/K, current_size/K);
}
}
guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
virtual_space()->committed_size() == max_size(), "Sanity");
return true;
}
size_t ASParNewGeneration::available_to_min_gen() {
assert(virtual_space()->committed_size() >= min_gen_size(), "Invariant");
return virtual_space()->committed_size() - min_gen_size();
}
void ASParNewGeneration::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");
CollectedHeap* heap = Universe::heap();
assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Sanity");
// We require eden and to space to be empty
if ((!eden()->is_empty()) || (!to()->is_empty())) {
return;
}
size_t cur_eden_size = eden()->capacity();
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr("ASParNew::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()->bottom(),
eden()->end(),
pointer_delta(eden()->end(),
eden()->bottom(),
sizeof(char)));
gclog_or_tty->print_cr(" from: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
from()->bottom(),
from()->end(),
pointer_delta(from()->end(),
from()->bottom(),
sizeof(char)));
gclog_or_tty->print_cr(" to: [" PTR_FORMAT ".." PTR_FORMAT ") "
SIZE_FORMAT,
to()->bottom(),
to()->end(),
pointer_delta( to()->end(),
to()->bottom(),
sizeof(char)));
}
// There's nothing to do if the new sizes are the same as the current
if (requested_survivor_size == to()->capacity() &&
requested_survivor_size == from()->capacity() &&
requested_eden_size == eden()->capacity()) {
if (PrintAdaptiveSizePolicy && Verbose) {
gclog_or_tty->print_cr(" capacities are the right sizes, returning");
}
return;
}
char* eden_start = (char*)eden()->bottom();
char* eden_end = (char*)eden()->end();
char* from_start = (char*)from()->bottom();
char* from_end = (char*)from()->end();
char* to_start = (char*)to()->bottom();
char* to_end = (char*)to()->end();
const size_t alignment = os::vm_page_size();
const bool maintain_minimum =
(requested_eden_size + 2 * requested_survivor_size) <= min_gen_size();
// Check whether from space is below to space
if (from_start < to_start) {
// 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_size = align_size_down(eden_size, alignment);
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()->end()) {
// Calculate the minimum offset possible for from_end
size_t from_size = pointer_delta(from()->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()->end(), "from_end moved to the right");
// Now update to_start with the new from_end
to_start = MAX2(from_end, to_start);
} else {
// If shrinking, move to-space down to abut the end of from-space
// so that shrinking will move to-space down. If not shrinking
// to-space is moving up to allow for growth on the next expansion.
if (requested_eden_size <= cur_eden_size) {
to_start = from_end;
if (to_start + requested_survivor_size > to_start) {
to_end = to_start + requested_survivor_size;
}
}
// else leave to_end pointing to the high end of the virtual space.
}
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:");
}
// Calculate the to-space boundaries based on
// the start of from-space.
to_end = from_start;
to_start = (char*)pointer_delta(from_start,
(char*)requested_survivor_size,
sizeof(char));
// Calculate the ideal eden boundaries.
// eden_end is already at the bottom of the generation
assert(eden_start == virtual_space()->low(),
"Eden is not starting at the low end of the virtual space");
if (eden_start + requested_eden_size >= eden_start) {
eden_end = eden_start + requested_eden_size;
} else {
eden_end = to_start;
}
// Does eden intrude into to-space? to-space
// gets priority but eden is not allowed to shrink
// to 0.
if (eden_end > to_start) {
eden_end = to_start;
}
// Don't let eden shrink down to 0 or less.
eden_end = MAX2(eden_end, eden_start + alignment);
assert(eden_start + alignment >= eden_start, "Overflow");
size_t eden_size;
if (maintain_minimum) {
// Use all the space available.
eden_end = MAX2(eden_end, to_start);
eden_size = pointer_delta(eden_end, eden_start, sizeof(char));
eden_size = MIN2(eden_size, cur_eden_size);
} else {
eden_size = pointer_delta(eden_end, eden_start, sizeof(char));
}
eden_size = align_size_down(eden_size, alignment);
assert(maintain_minimum || eden_size <= requested_eden_size,
"Eden size is too large");
assert(eden_size >= alignment, "Eden size is too small");
eden_end = eden_start + eden_size;
// Move to-space down to eden.
if (requested_eden_size < cur_eden_size) {
to_start = eden_end;
if (to_start + requested_survivor_size > to_start) {
to_end = MIN2(from_start, to_start + requested_survivor_size);
} else {
to_end = from_start;
}
}
// eden_end may have moved so again make sure
// the to-space and eden don't overlap.
to_start = MAX2(eden_end, to_start);
// from-space
size_t from_used = from()->used();
if (requested_survivor_size > from_used) {
if (from_start + requested_survivor_size >= from_start) {
from_end = from_start + requested_survivor_size;
}
if (from_end > virtual_space()->high()) {
from_end = virtual_space()->high();
}
}
assert(to_start >= eden_end, "to-space should be above eden");
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()->bottom(),
"from start moved to the right");
guarantee((HeapWord*)from_end >= from()->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()->top();
// For PrintAdaptiveSizePolicy block below
size_t old_from = from()->capacity();
size_t old_to = to()->capacity();
// If not clearing the spaces, do some checking to verify that
// the spaces are already mangled.
// Must check mangling before the spaces are reshaped. Otherwise,
// the bottom or end of one space may have moved into another
// a failure of the check may not correctly indicate which space
// is not properly mangled.
if (ZapUnusedHeapArea) {
HeapWord* limit = (HeapWord*) virtual_space()->high();
eden()->check_mangled_unused_area(limit);
from()->check_mangled_unused_area(limit);
to()->check_mangled_unused_area(limit);
}
// The call to initialize NULL's the next compaction space
eden()->initialize(edenMR,
SpaceDecorator::Clear,
SpaceDecorator::DontMangle);
eden()->set_next_compaction_space(from());
to()->initialize(toMR ,
SpaceDecorator::Clear,
SpaceDecorator::DontMangle);
from()->initialize(fromMR,
SpaceDecorator::DontClear,
SpaceDecorator::DontMangle);
assert(from()->top() == old_from_top, "from top changed!");
if (PrintAdaptiveSizePolicy) {
GenCollectedHeap* gch = GenCollectedHeap::heap();
assert(gch->kind() == CollectedHeap::GenCollectedHeap, "Sanity");
gclog_or_tty->print("AdaptiveSizePolicy::survivor space sizes: "
"collection: %d "
"(" SIZE_FORMAT ", " SIZE_FORMAT ") -> "
"(" SIZE_FORMAT ", " SIZE_FORMAT ") ",
gch->total_collections(),
old_from, old_to,
from()->capacity(),
to()->capacity());
gclog_or_tty->cr();
}
}
// Note that the the alignment used is the OS page size as
// opposed to an alignment associated with the virtual space
// (as is done in the ASPSYoungGen/ASPSOldGen)
bool ASParNewGeneration::resize_generation(size_t eden_size,
size_t survivor_size) {
const size_t alignment = os::vm_page_size();
size_t orig_size = virtual_space()->committed_size();
bool size_changed = false;
// There used to be this guarantee there.
// guarantee ((eden_size + 2*survivor_size) <= _max_gen_size, "incorrect input arguments");
// Code below forces this requirement. In addition the desired eden
// size and disired survivor sizes are desired goals and may
// exceed the total generation size.
assert(min_gen_size() <= orig_size && orig_size <= max_gen_size(),
"just checking");
// Adjust new generation size
const size_t eden_plus_survivors =
align_size_up(eden_size + 2 * survivor_size, alignment);
size_t desired_size = MAX2(MIN2(eden_plus_survivors, max_gen_size()),
min_gen_size());
assert(desired_size <= max_gen_size(), "just checking");
if (desired_size > orig_size) {
// Grow the generation
size_t change = desired_size - orig_size;
assert(change % alignment == 0, "just checking");
if (expand(change)) {
return false; // Error if we fail to resize!
}
size_changed = true;
} else if (desired_size < orig_size) {
size_t desired_change = orig_size - desired_size;
assert(desired_change % alignment == 0, "just checking");
desired_change = limit_gen_shrink(desired_change);
if (desired_change > 0) {
virtual_space()->shrink_by(desired_change);
reset_survivors_after_shrink();
size_changed = true;
}
} else {
if (Verbose && PrintGC) {
if (orig_size == max_gen_size()) {
gclog_or_tty->print_cr("ASParNew generation size at maximum: "
SIZE_FORMAT "K", orig_size/K);
} else if (orig_size == min_gen_size()) {
gclog_or_tty->print_cr("ASParNew generation size at minium: "
SIZE_FORMAT "K", orig_size/K);
}
}
}
if (size_changed) {
MemRegion cmr((HeapWord*)virtual_space()->low(),
(HeapWord*)virtual_space()->high());
GenCollectedHeap::heap()->barrier_set()->resize_covered_region(cmr);
if (Verbose && PrintGC) {
size_t current_size = virtual_space()->committed_size();
gclog_or_tty->print_cr("ASParNew generation size changed: "
SIZE_FORMAT "K->" SIZE_FORMAT "K",
orig_size/K, current_size/K);
}
}
guarantee(eden_plus_survivors <= virtual_space()->committed_size() ||
virtual_space()->committed_size() == max_gen_size(), "Sanity");
return true;
}
