Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/g1/g1StringDedup.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 | 1772223a25a2 |
children |
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/* * Copyright (c) 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 "gc_implementation/g1/g1CollectedHeap.inline.hpp" #include "gc_implementation/g1/g1GCPhaseTimes.hpp" #include "gc_implementation/g1/g1StringDedup.hpp" #include "gc_implementation/g1/g1StringDedupQueue.hpp" #include "gc_implementation/g1/g1StringDedupStat.hpp" #include "gc_implementation/g1/g1StringDedupTable.hpp" #include "gc_implementation/g1/g1StringDedupThread.hpp" bool G1StringDedup::_enabled = false; void G1StringDedup::initialize() { assert(UseG1GC, "String deduplication only available with G1"); if (UseStringDeduplication) { _enabled = true; G1StringDedupQueue::create(); G1StringDedupTable::create(); G1StringDedupThread::create(); } } void G1StringDedup::stop() { assert(is_enabled(), "String deduplication not enabled"); G1StringDedupThread::stop(); } bool G1StringDedup::is_candidate_from_mark(oop obj) { if (java_lang_String::is_instance(obj)) { bool from_young = G1CollectedHeap::heap()->heap_region_containing_raw(obj)->is_young(); if (from_young && obj->age() < StringDeduplicationAgeThreshold) { // Candidate found. String is being evacuated from young to old but has not // reached the deduplication age threshold, i.e. has not previously been a // candidate during its life in the young generation. return true; } } // Not a candidate return false; } void G1StringDedup::enqueue_from_mark(oop java_string) { assert(is_enabled(), "String deduplication not enabled"); if (is_candidate_from_mark(java_string)) { G1StringDedupQueue::push(0 /* worker_id */, java_string); } } bool G1StringDedup::is_candidate_from_evacuation(bool from_young, bool to_young, oop obj) { if (from_young && java_lang_String::is_instance(obj)) { if (to_young && obj->age() == StringDeduplicationAgeThreshold) { // Candidate found. String is being evacuated from young to young and just // reached the deduplication age threshold. return true; } if (!to_young && obj->age() < StringDeduplicationAgeThreshold) { // Candidate found. String is being evacuated from young to old but has not // reached the deduplication age threshold, i.e. has not previously been a // candidate during its life in the young generation. return true; } } // Not a candidate return false; } void G1StringDedup::enqueue_from_evacuation(bool from_young, bool to_young, uint worker_id, oop java_string) { assert(is_enabled(), "String deduplication not enabled"); if (is_candidate_from_evacuation(from_young, to_young, java_string)) { G1StringDedupQueue::push(worker_id, java_string); } } void G1StringDedup::deduplicate(oop java_string) { assert(is_enabled(), "String deduplication not enabled"); G1StringDedupStat dummy; // Statistics from this path is never used G1StringDedupTable::deduplicate(java_string, dummy); } void G1StringDedup::oops_do(OopClosure* keep_alive) { assert(is_enabled(), "String deduplication not enabled"); unlink_or_oops_do(NULL, keep_alive); } void G1StringDedup::unlink(BoolObjectClosure* is_alive) { assert(is_enabled(), "String deduplication not enabled"); // Don't allow a potential resize or rehash during unlink, as the unlink // operation itself might remove enough entries to invalidate such a decision. unlink_or_oops_do(is_alive, NULL, false /* allow_resize_and_rehash */); } // // Task for parallel unlink_or_oops_do() operation on the deduplication queue // and table. // class G1StringDedupUnlinkOrOopsDoTask : public AbstractGangTask { private: G1StringDedupUnlinkOrOopsDoClosure _cl; public: G1StringDedupUnlinkOrOopsDoTask(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) : AbstractGangTask("G1StringDedupUnlinkOrOopsDoTask"), _cl(is_alive, keep_alive, allow_resize_and_rehash) { } virtual void work(uint worker_id) { double queue_fixup_start = os::elapsedTime(); G1StringDedupQueue::unlink_or_oops_do(&_cl); double table_fixup_start = os::elapsedTime(); G1StringDedupTable::unlink_or_oops_do(&_cl, worker_id); double queue_fixup_time_ms = (table_fixup_start - queue_fixup_start) * 1000.0; double table_fixup_time_ms = (os::elapsedTime() - table_fixup_start) * 1000.0; G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); g1p->phase_times()->record_string_dedup_queue_fixup_worker_time(worker_id, queue_fixup_time_ms); g1p->phase_times()->record_string_dedup_table_fixup_worker_time(worker_id, table_fixup_time_ms); } }; void G1StringDedup::unlink_or_oops_do(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) { assert(is_enabled(), "String deduplication not enabled"); G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy(); g1p->phase_times()->note_string_dedup_fixup_start(); double fixup_start = os::elapsedTime(); G1StringDedupUnlinkOrOopsDoTask task(is_alive, keep_alive, allow_resize_and_rehash); if (G1CollectedHeap::use_parallel_gc_threads()) { G1CollectedHeap* g1h = G1CollectedHeap::heap(); g1h->set_par_threads(); g1h->workers()->run_task(&task); g1h->set_par_threads(0); } else { task.work(0); } double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0; g1p->phase_times()->record_string_dedup_fixup_time(fixup_time_ms); g1p->phase_times()->note_string_dedup_fixup_end(); } void G1StringDedup::threads_do(ThreadClosure* tc) { assert(is_enabled(), "String deduplication not enabled"); tc->do_thread(G1StringDedupThread::thread()); } void G1StringDedup::print_worker_threads_on(outputStream* st) { assert(is_enabled(), "String deduplication not enabled"); G1StringDedupThread::thread()->print_on(st); st->cr(); } void G1StringDedup::verify() { assert(is_enabled(), "String deduplication not enabled"); G1StringDedupQueue::verify(); G1StringDedupTable::verify(); } G1StringDedupUnlinkOrOopsDoClosure::G1StringDedupUnlinkOrOopsDoClosure(BoolObjectClosure* is_alive, OopClosure* keep_alive, bool allow_resize_and_rehash) : _is_alive(is_alive), _keep_alive(keep_alive), _resized_table(NULL), _rehashed_table(NULL), _next_queue(0), _next_bucket(0) { if (allow_resize_and_rehash) { // If both resize and rehash is needed, only do resize. Rehash of // the table will eventually happen if the situation persists. _resized_table = G1StringDedupTable::prepare_resize(); if (!is_resizing()) { _rehashed_table = G1StringDedupTable::prepare_rehash(); } } } G1StringDedupUnlinkOrOopsDoClosure::~G1StringDedupUnlinkOrOopsDoClosure() { assert(!is_resizing() || !is_rehashing(), "Can not both resize and rehash"); if (is_resizing()) { G1StringDedupTable::finish_resize(_resized_table); } else if (is_rehashing()) { G1StringDedupTable::finish_rehash(_rehashed_table); } }