Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/g1/g1MarkSweep.cpp @ 20543:e7d0505c8a30
8059758: Footprint regressions with JDK-8038423
Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything.
Reviewed-by: jwilhelm, brutisso
author | tschatzl |
---|---|
date | Fri, 10 Oct 2014 15:51:58 +0200 |
parents | d35872270666 |
children | 7848fc12602b |
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/* * Copyright (c) 2001, 2014, 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 "classfile/javaClasses.hpp" #include "classfile/symbolTable.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "code/codeCache.hpp" #include "code/icBuffer.hpp" #include "gc_implementation/g1/g1Log.hpp" #include "gc_implementation/g1/g1MarkSweep.hpp" #include "gc_implementation/g1/g1StringDedup.hpp" #include "gc_implementation/shared/gcHeapSummary.hpp" #include "gc_implementation/shared/gcTimer.hpp" #include "gc_implementation/shared/gcTrace.hpp" #include "gc_implementation/shared/gcTraceTime.hpp" #include "memory/gcLocker.hpp" #include "memory/genCollectedHeap.hpp" #include "memory/modRefBarrierSet.hpp" #include "memory/referencePolicy.hpp" #include "memory/space.hpp" #include "oops/instanceRefKlass.hpp" #include "oops/oop.inline.hpp" #include "prims/jvmtiExport.hpp" #include "runtime/biasedLocking.hpp" #include "runtime/fprofiler.hpp" #include "runtime/synchronizer.hpp" #include "runtime/thread.hpp" #include "runtime/vmThread.hpp" #include "utilities/copy.hpp" #include "utilities/events.hpp" class HeapRegion; void G1MarkSweep::invoke_at_safepoint(ReferenceProcessor* rp, bool clear_all_softrefs) { assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint"); SharedHeap* sh = SharedHeap::heap(); #ifdef ASSERT if (sh->collector_policy()->should_clear_all_soft_refs()) { assert(clear_all_softrefs, "Policy should have been checked earler"); } #endif // hook up weak ref data so it can be used during Mark-Sweep assert(GenMarkSweep::ref_processor() == NULL, "no stomping"); assert(rp != NULL, "should be non-NULL"); assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Precondition"); GenMarkSweep::_ref_processor = rp; rp->setup_policy(clear_all_softrefs); // When collecting the permanent generation Method*s may be moving, // so we either have to flush all bcp data or convert it into bci. CodeCache::gc_prologue(); Threads::gc_prologue(); bool marked_for_unloading = false; allocate_stacks(); // We should save the marks of the currently locked biased monitors. // The marking doesn't preserve the marks of biased objects. BiasedLocking::preserve_marks(); mark_sweep_phase1(marked_for_unloading, clear_all_softrefs); mark_sweep_phase2(); // Don't add any more derived pointers during phase3 COMPILER2_PRESENT(DerivedPointerTable::set_active(false)); mark_sweep_phase3(); mark_sweep_phase4(); GenMarkSweep::restore_marks(); BiasedLocking::restore_marks(); GenMarkSweep::deallocate_stacks(); // "free at last gc" is calculated from these. // CHF: cheating for now!!! // Universe::set_heap_capacity_at_last_gc(Universe::heap()->capacity()); // Universe::set_heap_used_at_last_gc(Universe::heap()->used()); Threads::gc_epilogue(); CodeCache::gc_epilogue(); JvmtiExport::gc_epilogue(); // refs processing: clean slate GenMarkSweep::_ref_processor = NULL; } void G1MarkSweep::allocate_stacks() { GenMarkSweep::_preserved_count_max = 0; GenMarkSweep::_preserved_marks = NULL; GenMarkSweep::_preserved_count = 0; } void G1MarkSweep::mark_sweep_phase1(bool& marked_for_unloading, bool clear_all_softrefs) { // Recursively traverse all live objects and mark them GCTraceTime tm("phase 1", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id()); GenMarkSweep::trace(" 1"); SharedHeap* sh = SharedHeap::heap(); // Need cleared claim bits for the roots processing ClassLoaderDataGraph::clear_claimed_marks(); MarkingCodeBlobClosure follow_code_closure(&GenMarkSweep::follow_root_closure, !CodeBlobToOopClosure::FixRelocations); sh->process_strong_roots(true, // activate StrongRootsScope SharedHeap::SO_None, &GenMarkSweep::follow_root_closure, &GenMarkSweep::follow_cld_closure, &follow_code_closure); // Process reference objects found during marking ReferenceProcessor* rp = GenMarkSweep::ref_processor(); assert(rp == G1CollectedHeap::heap()->ref_processor_stw(), "Sanity"); rp->setup_policy(clear_all_softrefs); const ReferenceProcessorStats& stats = rp->process_discovered_references(&GenMarkSweep::is_alive, &GenMarkSweep::keep_alive, &GenMarkSweep::follow_stack_closure, NULL, gc_timer(), gc_tracer()->gc_id()); gc_tracer()->report_gc_reference_stats(stats); // This is the point where the entire marking should have completed. assert(GenMarkSweep::_marking_stack.is_empty(), "Marking should have completed"); // Unload classes and purge the SystemDictionary. bool purged_class = SystemDictionary::do_unloading(&GenMarkSweep::is_alive); // Unload nmethods. CodeCache::do_unloading(&GenMarkSweep::is_alive, purged_class); // Prune dead klasses from subklass/sibling/implementor lists. Klass::clean_weak_klass_links(&GenMarkSweep::is_alive); // Delete entries for dead interned string and clean up unreferenced symbols in symbol table. G1CollectedHeap::heap()->unlink_string_and_symbol_table(&GenMarkSweep::is_alive); if (VerifyDuringGC) { HandleMark hm; // handle scope COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact); Universe::heap()->prepare_for_verify(); // Note: we can verify only the heap here. When an object is // marked, the previous value of the mark word (including // identity hash values, ages, etc) is preserved, and the mark // word is set to markOop::marked_value - effectively removing // any hash values from the mark word. These hash values are // used when verifying the dictionaries and so removing them // from the mark word can make verification of the dictionaries // fail. At the end of the GC, the orginal mark word values // (including hash values) are restored to the appropriate // objects. if (!VerifySilently) { gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying "); } Universe::heap()->verify(VerifySilently, VerifyOption_G1UseMarkWord); if (!VerifySilently) { gclog_or_tty->print_cr("]"); } } gc_tracer()->report_object_count_after_gc(&GenMarkSweep::is_alive); } void G1MarkSweep::mark_sweep_phase2() { // Now all live objects are marked, compute the new object addresses. // It is not required that we traverse spaces in the same order in // phase2, phase3 and phase4, but the ValidateMarkSweep live oops // tracking expects us to do so. See comment under phase4. GCTraceTime tm("phase 2", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id()); GenMarkSweep::trace("2"); prepare_compaction(); } class G1AdjustPointersClosure: public HeapRegionClosure { public: bool doHeapRegion(HeapRegion* r) { if (r->isHumongous()) { if (r->startsHumongous()) { // We must adjust the pointers on the single H object. oop obj = oop(r->bottom()); // point all the oops to the new location obj->adjust_pointers(); } } else { // This really ought to be "as_CompactibleSpace"... r->adjust_pointers(); } return false; } }; void G1MarkSweep::mark_sweep_phase3() { G1CollectedHeap* g1h = G1CollectedHeap::heap(); // Adjust the pointers to reflect the new locations GCTraceTime tm("phase 3", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id()); GenMarkSweep::trace("3"); SharedHeap* sh = SharedHeap::heap(); // Need cleared claim bits for the roots processing ClassLoaderDataGraph::clear_claimed_marks(); CodeBlobToOopClosure adjust_code_closure(&GenMarkSweep::adjust_pointer_closure, CodeBlobToOopClosure::FixRelocations); sh->process_all_roots(true, // activate StrongRootsScope SharedHeap::SO_AllCodeCache, &GenMarkSweep::adjust_pointer_closure, &GenMarkSweep::adjust_cld_closure, &adjust_code_closure); assert(GenMarkSweep::ref_processor() == g1h->ref_processor_stw(), "Sanity"); g1h->ref_processor_stw()->weak_oops_do(&GenMarkSweep::adjust_pointer_closure); // Now adjust pointers in remaining weak roots. (All of which should // have been cleared if they pointed to non-surviving objects.) sh->process_weak_roots(&GenMarkSweep::adjust_pointer_closure); if (G1StringDedup::is_enabled()) { G1StringDedup::oops_do(&GenMarkSweep::adjust_pointer_closure); } GenMarkSweep::adjust_marks(); G1AdjustPointersClosure blk; g1h->heap_region_iterate(&blk); } class G1SpaceCompactClosure: public HeapRegionClosure { public: G1SpaceCompactClosure() {} bool doHeapRegion(HeapRegion* hr) { if (hr->isHumongous()) { if (hr->startsHumongous()) { oop obj = oop(hr->bottom()); if (obj->is_gc_marked()) { obj->init_mark(); } else { assert(hr->is_empty(), "Should have been cleared in phase 2."); } hr->reset_during_compaction(); } } else { hr->compact(); } return false; } }; void G1MarkSweep::mark_sweep_phase4() { // All pointers are now adjusted, move objects accordingly // The ValidateMarkSweep live oops tracking expects us to traverse spaces // in the same order in phase2, phase3 and phase4. We don't quite do that // here (code and comment not fixed for perm removal), so we tell the validate code // to use a higher index (saved from phase2) when verifying perm_gen. G1CollectedHeap* g1h = G1CollectedHeap::heap(); GCTraceTime tm("phase 4", G1Log::fine() && Verbose, true, gc_timer(), gc_tracer()->gc_id()); GenMarkSweep::trace("4"); G1SpaceCompactClosure blk; g1h->heap_region_iterate(&blk); } void G1MarkSweep::prepare_compaction_work(G1PrepareCompactClosure* blk) { G1CollectedHeap* g1h = G1CollectedHeap::heap(); g1h->heap_region_iterate(blk); blk->update_sets(); } void G1PrepareCompactClosure::free_humongous_region(HeapRegion* hr) { HeapWord* end = hr->end(); FreeRegionList dummy_free_list("Dummy Free List for G1MarkSweep"); assert(hr->startsHumongous(), "Only the start of a humongous region should be freed."); hr->set_containing_set(NULL); _humongous_regions_removed.increment(1u, hr->capacity()); _g1h->free_humongous_region(hr, &dummy_free_list, false /* par */); prepare_for_compaction(hr, end); dummy_free_list.remove_all(); } void G1PrepareCompactClosure::prepare_for_compaction(HeapRegion* hr, HeapWord* end) { // If this is the first live region that we came across which we can compact, // initialize the CompactPoint. if (!is_cp_initialized()) { _cp.space = hr; _cp.threshold = hr->initialize_threshold(); } prepare_for_compaction_work(&_cp, hr, end); } void G1PrepareCompactClosure::prepare_for_compaction_work(CompactPoint* cp, HeapRegion* hr, HeapWord* end) { hr->prepare_for_compaction(cp); // Also clear the part of the card table that will be unused after // compaction. _mrbs->clear(MemRegion(hr->compaction_top(), end)); } void G1PrepareCompactClosure::update_sets() { // We'll recalculate total used bytes and recreate the free list // at the end of the GC, so no point in updating those values here. HeapRegionSetCount empty_set; _g1h->remove_from_old_sets(empty_set, _humongous_regions_removed); } bool G1PrepareCompactClosure::doHeapRegion(HeapRegion* hr) { if (hr->isHumongous()) { if (hr->startsHumongous()) { oop obj = oop(hr->bottom()); if (obj->is_gc_marked()) { obj->forward_to(obj); } else { free_humongous_region(hr); } } else { assert(hr->continuesHumongous(), "Invalid humongous."); } } else { prepare_for_compaction(hr, hr->end()); } return false; }