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);
}
// Compute desired plab size for one gc worker thread and latch result for later
// use. This should be called once at the end of parallel
// scavenge; it clears the sensor accumulators.
void PLABStats::adjust_desired_plab_sz() {
log_plab_allocation();
if (!ResizePLAB) {
// Clear accumulators for next round.
reset();
return;
}
assert(is_object_aligned(max_size()) && min_size() <= max_size(),
"PLAB clipping computation may be incorrect");
if (_allocated == 0) {
assert(_unused == 0,
"Inconsistency in PLAB stats: "
"_allocated: " SIZE_FORMAT ", "
"_wasted: " SIZE_FORMAT ", "
"_unused: " SIZE_FORMAT ", "
"_undo_wasted: " SIZE_FORMAT,
_allocated, _wasted, _unused, _undo_wasted);
_allocated = 1;
}
double wasted_frac = (double)_unused / (double)_allocated;
size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct);
if (target_refills == 0) {
target_refills = 1;
}
size_t used = _allocated - _wasted - _unused;
// Assumed to have 1 gc worker thread
size_t recent_plab_sz = used / target_refills;
// Take historical weighted average
_filter.sample(recent_plab_sz);
// Clip from above and below, and align to object boundary
size_t new_plab_sz = MAX2(min_size(), (size_t)_filter.average());
new_plab_sz = MIN2(max_size(), new_plab_sz);
new_plab_sz = align_object_size(new_plab_sz);
// Latch the result
_desired_net_plab_sz = new_plab_sz;
log_sizing(recent_plab_sz, new_plab_sz);
reset();
}
// Compute desired plab size and latch result for later
// use. This should be called once at the end of parallel
// scavenge; it clears the sensor accumulators.
void PLABStats::adjust_desired_plab_sz(uint no_of_gc_workers) {
assert(ResizePLAB, "Not set");
assert(is_object_aligned(max_size()) && min_size() <= max_size(),
"PLAB clipping computation may be incorrect");
if (_allocated == 0) {
assert(_unused == 0,
err_msg("Inconsistency in PLAB stats: "
"_allocated: "SIZE_FORMAT", "
"_wasted: "SIZE_FORMAT", "
"_unused: "SIZE_FORMAT", "
"_used : "SIZE_FORMAT,
_allocated, _wasted, _unused, _used));
_allocated = 1;
}
double wasted_frac = (double)_unused/(double)_allocated;
size_t target_refills = (size_t)((wasted_frac*TargetSurvivorRatio)/
TargetPLABWastePct);
if (target_refills == 0) {
target_refills = 1;
}
_used = _allocated - _wasted - _unused;
size_t plab_sz = _used/(target_refills*no_of_gc_workers);
if (PrintPLAB) gclog_or_tty->print(" (plab_sz = %d ", plab_sz);
// Take historical weighted average
_filter.sample(plab_sz);
// Clip from above and below, and align to object boundary
plab_sz = MAX2(min_size(), (size_t)_filter.average());
plab_sz = MIN2(max_size(), plab_sz);
plab_sz = align_object_size(plab_sz);
// Latch the result
if (PrintPLAB) gclog_or_tty->print(" desired_plab_sz = %d) ", plab_sz);
_desired_plab_sz = plab_sz;
// Now clear the accumulators for next round:
// note this needs to be fixed in the case where we
// are retaining across scavenges. FIX ME !!! XXX
_allocated = 0;
_wasted = 0;
_unused = 0;
}
HeapWord* PSYoungPromotionLAB::allocate(size_t size) {
// Can't assert this, when young fills, we keep the LAB around, but flushed.
// assert(_state != flushed, "Sanity");
HeapWord* obj = CollectedHeap::align_allocation_or_fail(top(), end(), SurvivorAlignmentInBytes);
if (obj == NULL) {
return NULL;
}
HeapWord* new_top = obj + size;
// The 'new_top>obj' check is needed to detect overflow of obj+size.
if (new_top > obj && new_top <= end()) {
set_top(new_top);
assert(is_ptr_aligned(obj, SurvivorAlignmentInBytes) && is_object_aligned((intptr_t)new_top),
"checking alignment");
return obj;
} else {
set_top(obj);
return NULL;
}
}
// Compute desired plab size and latch result for later
// use. This should be called once at the end of parallel
// scavenge; it clears the sensor accumulators.
void PLABStats::adjust_desired_plab_sz(uint no_of_gc_workers) {
assert(ResizePLAB, "Not set");
assert(is_object_aligned(max_size()) && min_size() <= max_size(),
"PLAB clipping computation may be incorrect");
if (_allocated == 0) {
assert(_unused == 0,
err_msg("Inconsistency in PLAB stats: "
"_allocated: "SIZE_FORMAT", "
"_wasted: "SIZE_FORMAT", "
"_unused: "SIZE_FORMAT,
_allocated, _wasted, _unused));
_allocated = 1;
}
double wasted_frac = (double)_unused / (double)_allocated;
size_t target_refills = (size_t)((wasted_frac * TargetSurvivorRatio) / TargetPLABWastePct);
if (target_refills == 0) {
target_refills = 1;
}
size_t used = _allocated - _wasted - _unused;
size_t recent_plab_sz = used / (target_refills * no_of_gc_workers);
// Take historical weighted average
_filter.sample(recent_plab_sz);
// Clip from above and below, and align to object boundary
size_t new_plab_sz = MAX2(min_size(), (size_t)_filter.average());
new_plab_sz = MIN2(max_size(), new_plab_sz);
new_plab_sz = align_object_size(new_plab_sz);
// Latch the result
if (PrintPLAB) {
gclog_or_tty->print(" (plab_sz = " SIZE_FORMAT" desired_plab_sz = " SIZE_FORMAT") ", recent_plab_sz, new_plab_sz);
}
_desired_plab_sz = new_plab_sz;
reset();
}
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 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 G1EvacStats::adjust_desired_plab_sz() {
log_plab_allocation();
if (!ResizePLAB) {
// Clear accumulators for next round.
reset();
return;
}
assert(is_object_aligned(max_size()) && min_size() <= max_size(),
"PLAB clipping computation may be incorrect");
if (_allocated == 0) {
assert((_unused == 0),
"Inconsistency in PLAB stats: "
"_allocated: " SIZE_FORMAT ", "
"_wasted: " SIZE_FORMAT ", "
"_region_end_waste: " SIZE_FORMAT ", "
"_unused: " SIZE_FORMAT ", "
"_used : " SIZE_FORMAT,
_allocated, _wasted, _region_end_waste, _unused, used());
_allocated = 1;
}
// The size of the PLAB caps the amount of space that can be wasted at the
// end of the collection. In the worst case the last PLAB could be completely
// empty.
// This allows us to calculate the new PLAB size to achieve the
// TargetPLABWastePct given the latest memory usage and that the last buffer
// will be G1LastPLABAverageOccupancy full.
//
// E.g. assume that if in the current GC 100 words were allocated and a
// TargetPLABWastePct of 10 had been set.
//
// So we could waste up to 10 words to meet that percentage. Given that we
// also assume that that buffer is typically half-full, the new desired PLAB
// size is set to 20 words.
//
// The amount of allocation performed should be independent of the number of
// threads, so should the maximum waste we can spend in total. So if
// we used n threads to allocate, each of them can spend maximum waste/n words in
// a first rough approximation. The number of threads only comes into play later
// when actually retrieving the actual desired PLAB size.
//
// After calculating this optimal PLAB size the algorithm applies the usual
// exponential decaying average over this value to guess the next PLAB size.
//
// We account region end waste fully to PLAB allocation (in the calculation of
// what we consider as "used_for_waste_calculation" below). This is not
// completely fair, but is a conservative assumption because PLABs may be sized
// flexibly while we cannot adjust inline allocations.
// Allocation during GC will try to minimize region end waste so this impact
// should be minimal.
//
// We need to cover overflow when calculating the amount of space actually used
// by objects in PLABs when subtracting the region end waste.
// Region end waste may be higher than actual allocation. This may occur if many
// threads do not allocate anything but a few rather large objects. In this
// degenerate case the PLAB size would simply quickly tend to minimum PLAB size,
// which is an okay reaction.
size_t const used_for_waste_calculation = used() > _region_end_waste ? used() - _region_end_waste : 0;
size_t const total_waste_allowed = used_for_waste_calculation * TargetPLABWastePct;
size_t const cur_plab_sz = (size_t)((double)total_waste_allowed / G1LastPLABAverageOccupancy);
// Take historical weighted average
_filter.sample(cur_plab_sz);
_desired_net_plab_sz = MAX2(min_size(), (size_t)_filter.average());
log_sizing(cur_plab_sz, _desired_net_plab_sz);
// Clear accumulators for next round.
reset();
}
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();
}
}
