/* * Copyright (c) 2003, 2020, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "gc/parallel/asPSYoungGen.hpp" #include "gc/parallel/parallelScavengeHeap.hpp" #include "gc/parallel/psScavenge.inline.hpp" #include "gc/parallel/psYoungGen.hpp" #include "gc/shared/gcUtil.hpp" #include "gc/shared/genArguments.hpp" #include "gc/shared/spaceDecorator.inline.hpp" #include "oops/oop.inline.hpp" #include "runtime/java.hpp" #include "utilities/align.hpp" ASPSYoungGen::ASPSYoungGen(size_t init_byte_size, size_t minimum_byte_size, size_t byte_size_limit) : PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit), _gen_size_limit(byte_size_limit) { } ASPSYoungGen::ASPSYoungGen(PSVirtualSpace* vs, size_t init_byte_size, size_t minimum_byte_size, size_t byte_size_limit) : //PSYoungGen(init_byte_size, minimum_byte_size, byte_size_limit), PSYoungGen(vs->committed_size(), minimum_byte_size, byte_size_limit), _gen_size_limit(byte_size_limit) { assert(vs->committed_size() == init_byte_size, "Cannot replace with"); _virtual_space = vs; } void ASPSYoungGen::initialize_virtual_space(ReservedSpace rs, size_t alignment) { assert(_init_gen_size != 0, "Should have a finite size"); _virtual_space = new PSVirtualSpaceHighToLow(rs, alignment); if (!_virtual_space->expand_by(_init_gen_size)) { vm_exit_during_initialization("Could not reserve enough space for object heap"); } } void ASPSYoungGen::initialize(ReservedSpace rs, size_t alignment) { initialize_virtual_space(rs, alignment); initialize_work(); } size_t ASPSYoungGen::available_for_expansion() { size_t current_committed_size = virtual_space()->committed_size(); assert((gen_size_limit() >= current_committed_size), "generation size limit is wrong"); size_t result = gen_size_limit() - current_committed_size; size_t result_aligned = align_down(result, GenAlignment); 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::heap(); const size_t eden_alignment = SpaceAlignment; 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_down(eden_avail, GenAlignment); 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_down(result, GenAlignment); log_trace(gc, ergo)("ASPSYoungGen::available_for_contraction: " SIZE_FORMAT " K", result_aligned/K); log_trace(gc, ergo)(" max_contraction " SIZE_FORMAT " K", max_contraction/K); log_trace(gc, ergo)(" eden_avail " SIZE_FORMAT " K", eden_avail/K); log_trace(gc, ergo)(" gen_avail " SIZE_FORMAT " K", gen_avail/K); return result_aligned; } return 0; } // The current implementation only considers to the end of eden. // If to_space is below from_space, to_space is not considered. // to_space can be. size_t ASPSYoungGen::available_to_live() { const size_t alignment = SpaceAlignment; // Include any space that is committed but is not in eden. size_t available = pointer_delta(eden_space()->bottom(), virtual_space()->low(), sizeof(char)); const size_t eden_capacity = eden_space()->capacity_in_bytes(); if (eden_space()->is_empty() && eden_capacity > alignment) { available += eden_capacity - alignment; } return available; } // 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_up(eden_size + 2 * survivor_size, alignment); size_t desired_size = clamp(eden_plus_survivors, min_gen_size(), gen_size_limit()); 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 (orig_size == gen_size_limit()) { log_trace(gc)("ASPSYoung generation size at maximum: " SIZE_FORMAT "K", orig_size/K); } else if (orig_size == min_gen_size()) { log_trace(gc)("ASPSYoung generation size at minium: " SIZE_FORMAT "K", orig_size/K); } } if (size_changed) { reset_after_change(); log_trace(gc)("ASPSYoung generation size changed: " SIZE_FORMAT "K->" SIZE_FORMAT "K", orig_size/K, virtual_space()->committed_size()/K); } guarantee(eden_plus_survivors <= virtual_space()->committed_size() || virtual_space()->committed_size() == max_size(), "Sanity"); return true; } // Similar to PSYoungGen::resize_spaces() but // eden always starts at the low end of the committed virtual space // current implementation does not allow holes between the spaces // _young_generation_boundary has to be reset because it changes. // so additional verification 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; } log_trace(gc, ergo)("PSYoungGen::resize_spaces(requested_eden_size: " SIZE_FORMAT ", requested_survivor_size: " SIZE_FORMAT ")", requested_eden_size, requested_survivor_size); log_trace(gc, ergo)(" eden: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, p2i(eden_space()->bottom()), p2i(eden_space()->end()), pointer_delta(eden_space()->end(), eden_space()->bottom(), sizeof(char))); log_trace(gc, ergo)(" from: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, p2i(from_space()->bottom()), p2i(from_space()->end()), pointer_delta(from_space()->end(), from_space()->bottom(), sizeof(char))); log_trace(gc, ergo)(" to: [" PTR_FORMAT ".." PTR_FORMAT ") " SIZE_FORMAT, p2i(to_space()->bottom()), p2i(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()) { log_trace(gc, ergo)(" 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::heap(); 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 log_trace(gc, ergo)(" 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()) { // 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 = SpaceAlignment; } else { from_size = align_up(from_size, SpaceAlignment); } 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"); log_trace(gc, ergo)(" [eden_start .. eden_end): " "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, p2i(eden_start), p2i(eden_end), pointer_delta(eden_end, eden_start, sizeof(char))); log_trace(gc, ergo)(" [from_start .. from_end): " "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, p2i(from_start), p2i(from_end), pointer_delta(from_end, from_start, sizeof(char))); log_trace(gc, ergo)(" [ to_start .. to_end): " "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, p2i(to_start), p2i(to_end), pointer_delta( to_end, to_start, sizeof(char))); } else { // Eden, to, from log_trace(gc, ergo)(" 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 + SpaceAlignment); // 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 + SpaceAlignment); to_start = MAX2(to_start, eden_end); log_trace(gc, ergo)(" [eden_start .. eden_end): " "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, p2i(eden_start), p2i(eden_end), pointer_delta(eden_end, eden_start, sizeof(char))); log_trace(gc, ergo)(" [ to_start .. to_end): " "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, p2i(to_start), p2i(to_end), pointer_delta( to_end, to_start, sizeof(char))); log_trace(gc, ergo)(" [from_start .. from_end): " "[" PTR_FORMAT " .. " PTR_FORMAT ") " SIZE_FORMAT, p2i(from_start), p2i(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(eden_start), "checking alignment"); assert(is_object_aligned(from_start), "checking alignment"); assert(is_object_aligned(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 logging 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); PSScavenge::set_young_generation_boundary(eden_space()->bottom()); assert(from_space()->top() == old_from_top, "from top changed!"); log_trace(gc, ergo)("AdaptiveSizePolicy::survivor space sizes: " "collection: %d " "(" SIZE_FORMAT ", " SIZE_FORMAT ") -> " "(" SIZE_FORMAT ", " SIZE_FORMAT ") ", ParallelScavengeHeap::heap()->total_collections(), old_from, old_to, from_space()->capacity_in_bytes(), to_space()->capacity_in_bytes()); space_invariants(); } void ASPSYoungGen::reset_after_change() { assert_locked_or_safepoint(Heap_lock); _reserved = MemRegion((HeapWord*)virtual_space()->low_boundary(), (HeapWord*)virtual_space()->high_boundary()); PSScavenge::set_subject_to_discovery_span(_reserved); HeapWord* new_eden_bottom = (HeapWord*)virtual_space()->low(); HeapWord* eden_bottom = eden_space()->bottom(); if (new_eden_bottom != eden_bottom) { MemRegion eden_mr(new_eden_bottom, eden_space()->end()); eden_space()->initialize(eden_mr, SpaceDecorator::Clear, SpaceDecorator::Mangle); PSScavenge::set_young_generation_boundary(eden_space()->bottom()); } MemRegion cmr((HeapWord*)virtual_space()->low(), (HeapWord*)virtual_space()->high()); ParallelScavengeHeap::heap()->barrier_set()->card_table()->resize_covered_region(cmr); space_invariants(); }