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view src/share/vm/prims/jvmtiTagMap.hpp @ 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 | 8b46b0196eb0 |
children |
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/* * Copyright (c) 2003, 2013, 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. * */ // JvmtiTagMap #ifndef SHARE_VM_PRIMS_JVMTITAGMAP_HPP #define SHARE_VM_PRIMS_JVMTITAGMAP_HPP #include "gc_interface/collectedHeap.hpp" #include "jvmtifiles/jvmti.h" #include "jvmtifiles/jvmtiEnv.hpp" #include "memory/allocation.hpp" #include "memory/genCollectedHeap.hpp" #include "memory/universe.hpp" // forward references class JvmtiTagHashmap; class JvmtiTagHashmapEntry; class JvmtiTagHashmapEntryClosure; class JvmtiTagMap : public CHeapObj<mtInternal> { private: enum{ max_free_entries = 4096 // maximum number of free entries per env }; JvmtiEnv* _env; // the jvmti environment Mutex _lock; // lock for this tag map JvmtiTagHashmap* _hashmap; // the hashmap JvmtiTagHashmapEntry* _free_entries; // free list for this environment int _free_entries_count; // number of entries on the free list // create a tag map JvmtiTagMap(JvmtiEnv* env); // accessors inline Mutex* lock() { return &_lock; } inline JvmtiEnv* env() const { return _env; } void do_weak_oops(BoolObjectClosure* is_alive, OopClosure* f); // iterate over all entries in this tag map void entry_iterate(JvmtiTagHashmapEntryClosure* closure); public: // indicates if this tag map is locked bool is_locked() { return lock()->is_locked(); } JvmtiTagHashmap* hashmap() { return _hashmap; } // create/destroy entries JvmtiTagHashmapEntry* create_entry(oop ref, jlong tag); void destroy_entry(JvmtiTagHashmapEntry* entry); // returns true if the hashmaps are empty bool is_empty(); // return tag for the given environment static JvmtiTagMap* tag_map_for(JvmtiEnv* env); // destroy tag map ~JvmtiTagMap(); // set/get tag void set_tag(jobject obj, jlong tag); jlong get_tag(jobject obj); // deprecated heap iteration functions void iterate_over_heap(jvmtiHeapObjectFilter object_filter, KlassHandle klass, jvmtiHeapObjectCallback heap_object_callback, const void* user_data); void iterate_over_reachable_objects(jvmtiHeapRootCallback heap_root_callback, jvmtiStackReferenceCallback stack_ref_callback, jvmtiObjectReferenceCallback object_ref_callback, const void* user_data); void iterate_over_objects_reachable_from_object(jobject object, jvmtiObjectReferenceCallback object_reference_callback, const void* user_data); // advanced (JVMTI 1.1) heap iteration functions void iterate_through_heap(jint heap_filter, KlassHandle klass, const jvmtiHeapCallbacks* callbacks, const void* user_data); void follow_references(jint heap_filter, KlassHandle klass, jobject initial_object, const jvmtiHeapCallbacks* callbacks, const void* user_data); // get tagged objects jvmtiError get_objects_with_tags(const jlong* tags, jint count, jint* count_ptr, jobject** object_result_ptr, jlong** tag_result_ptr); static void weak_oops_do( BoolObjectClosure* is_alive, OopClosure* f) NOT_JVMTI_RETURN; }; #endif // SHARE_VM_PRIMS_JVMTITAGMAP_HPP