--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/g1AllocRegion.cpp Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,310 @@
+/*
+ * Copyright (c) 2011, 2016, 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/g1/g1AllocRegion.inline.hpp"
+#include "gc/g1/g1EvacStats.inline.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "logging/log.hpp"
+#include "logging/logStream.hpp"
+#include "memory/resourceArea.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "utilities/align.hpp"
+
+G1CollectedHeap* G1AllocRegion::_g1h = NULL;
+HeapRegion* G1AllocRegion::_dummy_region = NULL;
+
+void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {
+ assert(_dummy_region == NULL, "should be set once");
+ assert(dummy_region != NULL, "pre-condition");
+ assert(dummy_region->free() == 0, "pre-condition");
+
+ // Make sure that any allocation attempt on this region will fail
+ // and will not trigger any asserts.
+ assert(allocate(dummy_region, 1, false) == NULL, "should fail");
+ assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");
+ assert(allocate(dummy_region, 1, true) == NULL, "should fail");
+ assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");
+
+ _g1h = g1h;
+ _dummy_region = dummy_region;
+}
+
+size_t G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,
+ bool bot_updates) {
+ assert(alloc_region != NULL && alloc_region != _dummy_region,
+ "pre-condition");
+ size_t result = 0;
+
+ // Other threads might still be trying to allocate using a CAS out
+ // of the region we are trying to retire, as they can do so without
+ // holding the lock. So, we first have to make sure that noone else
+ // can allocate out of it by doing a maximal allocation. Even if our
+ // CAS attempt fails a few times, we'll succeed sooner or later
+ // given that failed CAS attempts mean that the region is getting
+ // closed to being full.
+ size_t free_word_size = alloc_region->free() / HeapWordSize;
+
+ // This is the minimum free chunk we can turn into a dummy
+ // object. If the free space falls below this, then noone can
+ // allocate in this region anyway (all allocation requests will be
+ // of a size larger than this) so we won't have to perform the dummy
+ // allocation.
+ size_t min_word_size_to_fill = CollectedHeap::min_fill_size();
+
+ while (free_word_size >= min_word_size_to_fill) {
+ HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);
+ if (dummy != NULL) {
+ // If the allocation was successful we should fill in the space.
+ CollectedHeap::fill_with_object(dummy, free_word_size);
+ alloc_region->set_pre_dummy_top(dummy);
+ result += free_word_size * HeapWordSize;
+ break;
+ }
+
+ free_word_size = alloc_region->free() / HeapWordSize;
+ // It's also possible that someone else beats us to the
+ // allocation and they fill up the region. In that case, we can
+ // just get out of the loop.
+ }
+ result += alloc_region->free();
+
+ assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,
+ "post-condition");
+ return result;
+}
+
+size_t G1AllocRegion::retire(bool fill_up) {
+ assert_alloc_region(_alloc_region != NULL, "not initialized properly");
+
+ size_t result = 0;
+
+ trace("retiring");
+ HeapRegion* alloc_region = _alloc_region;
+ if (alloc_region != _dummy_region) {
+ // We never have to check whether the active region is empty or not,
+ // and potentially free it if it is, given that it's guaranteed that
+ // it will never be empty.
+ assert_alloc_region(!alloc_region->is_empty(),
+ "the alloc region should never be empty");
+
+ if (fill_up) {
+ result = fill_up_remaining_space(alloc_region, _bot_updates);
+ }
+
+ assert_alloc_region(alloc_region->used() >= _used_bytes_before, "invariant");
+ size_t allocated_bytes = alloc_region->used() - _used_bytes_before;
+ retire_region(alloc_region, allocated_bytes);
+ _used_bytes_before = 0;
+ _alloc_region = _dummy_region;
+ }
+ trace("retired");
+
+ return result;
+}
+
+HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,
+ bool force) {
+ assert_alloc_region(_alloc_region == _dummy_region, "pre-condition");
+ assert_alloc_region(_used_bytes_before == 0, "pre-condition");
+
+ trace("attempting region allocation");
+ HeapRegion* new_alloc_region = allocate_new_region(word_size, force);
+ if (new_alloc_region != NULL) {
+ new_alloc_region->reset_pre_dummy_top();
+ // Need to do this before the allocation
+ _used_bytes_before = new_alloc_region->used();
+ HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);
+ assert_alloc_region(result != NULL, "the allocation should succeeded");
+
+ OrderAccess::storestore();
+ // Note that we first perform the allocation and then we store the
+ // region in _alloc_region. This is the reason why an active region
+ // can never be empty.
+ update_alloc_region(new_alloc_region);
+ trace("region allocation successful");
+ return result;
+ } else {
+ trace("region allocation failed");
+ return NULL;
+ }
+ ShouldNotReachHere();
+}
+
+void G1AllocRegion::init() {
+ trace("initializing");
+ assert_alloc_region(_alloc_region == NULL && _used_bytes_before == 0, "pre-condition");
+ assert_alloc_region(_dummy_region != NULL, "should have been set");
+ _alloc_region = _dummy_region;
+ _count = 0;
+ trace("initialized");
+}
+
+void G1AllocRegion::set(HeapRegion* alloc_region) {
+ trace("setting");
+ // We explicitly check that the region is not empty to make sure we
+ // maintain the "the alloc region cannot be empty" invariant.
+ assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");
+ assert_alloc_region(_alloc_region == _dummy_region &&
+ _used_bytes_before == 0 && _count == 0,
+ "pre-condition");
+
+ _used_bytes_before = alloc_region->used();
+ _alloc_region = alloc_region;
+ _count += 1;
+ trace("set");
+}
+
+void G1AllocRegion::update_alloc_region(HeapRegion* alloc_region) {
+ trace("update");
+ // We explicitly check that the region is not empty to make sure we
+ // maintain the "the alloc region cannot be empty" invariant.
+ assert_alloc_region(alloc_region != NULL && !alloc_region->is_empty(), "pre-condition");
+
+ _alloc_region = alloc_region;
+ _alloc_region->set_allocation_context(allocation_context());
+ _count += 1;
+ trace("updated");
+}
+
+HeapRegion* G1AllocRegion::release() {
+ trace("releasing");
+ HeapRegion* alloc_region = _alloc_region;
+ retire(false /* fill_up */);
+ assert_alloc_region(_alloc_region == _dummy_region, "post-condition of retire()");
+ _alloc_region = NULL;
+ trace("released");
+ return (alloc_region == _dummy_region) ? NULL : alloc_region;
+}
+
+#ifndef PRODUCT
+void G1AllocRegion::trace(const char* str, size_t min_word_size, size_t desired_word_size, size_t actual_word_size, HeapWord* result) {
+ // All the calls to trace that set either just the size or the size
+ // and the result are considered part of detailed tracing and are
+ // skipped during other tracing.
+
+ Log(gc, alloc, region) log;
+
+ if (!log.is_debug()) {
+ return;
+ }
+
+ bool detailed_info = log.is_trace();
+
+ if ((actual_word_size == 0 && result == NULL) || detailed_info) {
+ ResourceMark rm;
+ LogStream ls_trace(log.trace());
+ LogStream ls_debug(log.debug());
+ outputStream* out = detailed_info ? &ls_trace : &ls_debug;
+
+ out->print("%s: %u ", _name, _count);
+
+ if (_alloc_region == NULL) {
+ out->print("NULL");
+ } else if (_alloc_region == _dummy_region) {
+ out->print("DUMMY");
+ } else {
+ out->print(HR_FORMAT, HR_FORMAT_PARAMS(_alloc_region));
+ }
+
+ out->print(" : %s", str);
+
+ if (detailed_info) {
+ if (result != NULL) {
+ out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT " actual " SIZE_FORMAT " " PTR_FORMAT,
+ min_word_size, desired_word_size, actual_word_size, p2i(result));
+ } else if (min_word_size != 0) {
+ out->print(" min " SIZE_FORMAT " desired " SIZE_FORMAT, min_word_size, desired_word_size);
+ }
+ }
+ out->cr();
+ }
+}
+#endif // PRODUCT
+
+G1AllocRegion::G1AllocRegion(const char* name,
+ bool bot_updates)
+ : _name(name), _bot_updates(bot_updates),
+ _alloc_region(NULL), _count(0), _used_bytes_before(0),
+ _allocation_context(AllocationContext::system()) { }
+
+
+HeapRegion* MutatorAllocRegion::allocate_new_region(size_t word_size,
+ bool force) {
+ return _g1h->new_mutator_alloc_region(word_size, force);
+}
+
+void MutatorAllocRegion::retire_region(HeapRegion* alloc_region,
+ size_t allocated_bytes) {
+ _g1h->retire_mutator_alloc_region(alloc_region, allocated_bytes);
+}
+
+HeapRegion* G1GCAllocRegion::allocate_new_region(size_t word_size,
+ bool force) {
+ assert(!force, "not supported for GC alloc regions");
+ return _g1h->new_gc_alloc_region(word_size, _purpose);
+}
+
+void G1GCAllocRegion::retire_region(HeapRegion* alloc_region,
+ size_t allocated_bytes) {
+ _g1h->retire_gc_alloc_region(alloc_region, allocated_bytes, _purpose);
+}
+
+size_t G1GCAllocRegion::retire(bool fill_up) {
+ HeapRegion* retired = get();
+ size_t end_waste = G1AllocRegion::retire(fill_up);
+ // Do not count retirement of the dummy allocation region.
+ if (retired != NULL) {
+ _stats->add_region_end_waste(end_waste / HeapWordSize);
+ }
+ return end_waste;
+}
+
+HeapRegion* OldGCAllocRegion::release() {
+ HeapRegion* cur = get();
+ if (cur != NULL) {
+ // Determine how far we are from the next card boundary. If it is smaller than
+ // the minimum object size we can allocate into, expand into the next card.
+ HeapWord* top = cur->top();
+ HeapWord* aligned_top = align_up(top, BOTConstants::N_bytes);
+
+ size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
+
+ if (to_allocate_words != 0) {
+ // We are not at a card boundary. Fill up, possibly into the next, taking the
+ // end of the region and the minimum object size into account.
+ to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
+ MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
+
+ // Skip allocation if there is not enough space to allocate even the smallest
+ // possible object. In this case this region will not be retained, so the
+ // original problem cannot occur.
+ if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
+ HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
+ CollectedHeap::fill_with_object(dummy, to_allocate_words);
+ }
+ }
+ }
+ return G1AllocRegion::release();
+}