| /* |
| * Copyright (c) 2015, 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/g1CollectedHeap.inline.hpp" |
| #include "gc/g1/g1CollectorPolicy.hpp" |
| #include "gc/g1/g1CollectionSet.hpp" |
| #include "gc/g1/g1YoungRemSetSamplingThread.hpp" |
| #include "gc/g1/heapRegion.inline.hpp" |
| #include "gc/g1/heapRegionRemSet.hpp" |
| #include "gc/g1/suspendibleThreadSet.hpp" |
| #include "runtime/mutexLocker.hpp" |
| |
| G1YoungRemSetSamplingThread::G1YoungRemSetSamplingThread() : |
| ConcurrentGCThread(), |
| _monitor(Mutex::nonleaf, |
| "G1YoungRemSetSamplingThread monitor", |
| true, |
| Monitor::_safepoint_check_never) { |
| set_name("G1 Young RemSet Sampling"); |
| create_and_start(); |
| } |
| |
| void G1YoungRemSetSamplingThread::sleep_before_next_cycle() { |
| MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag); |
| if (!should_terminate()) { |
| uintx waitms = G1ConcRefinementServiceIntervalMillis; // 300, really should be? |
| _monitor.wait(Mutex::_no_safepoint_check_flag, waitms); |
| } |
| } |
| |
| void G1YoungRemSetSamplingThread::run_service() { |
| double vtime_start = os::elapsedVTime(); |
| |
| while (!should_terminate()) { |
| sample_young_list_rs_lengths(); |
| |
| if (os::supports_vtime()) { |
| _vtime_accum = (os::elapsedVTime() - vtime_start); |
| } else { |
| _vtime_accum = 0.0; |
| } |
| |
| sleep_before_next_cycle(); |
| } |
| } |
| |
| void G1YoungRemSetSamplingThread::stop_service() { |
| MutexLockerEx x(&_monitor, Mutex::_no_safepoint_check_flag); |
| _monitor.notify(); |
| } |
| |
| void G1YoungRemSetSamplingThread::sample_young_list_rs_lengths() { |
| SuspendibleThreadSetJoiner sts; |
| G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| G1CollectorPolicy* g1p = g1h->g1_policy(); |
| if (g1p->adaptive_young_list_length()) { |
| int regions_visited = 0; |
| HeapRegion* hr = g1h->young_list()->first_region(); |
| size_t sampled_rs_lengths = 0; |
| |
| while (hr != NULL) { |
| size_t rs_length = hr->rem_set()->occupied(); |
| sampled_rs_lengths += rs_length; |
| |
| // The current region may not yet have been added to the |
| // incremental collection set (it gets added when it is |
| // retired as the current allocation region). |
| if (hr->in_collection_set()) { |
| // Update the collection set policy information for this region |
| g1h->collection_set()->update_young_region_prediction(hr, rs_length); |
| } |
| |
| ++regions_visited; |
| |
| // we try to yield every time we visit 10 regions |
| if (regions_visited == 10) { |
| if (sts.should_yield()) { |
| sts.yield(); |
| // A gc may have occurred and our sampling data is stale and further |
| // traversal of the young list is unsafe |
| return; |
| } |
| regions_visited = 0; |
| } |
| hr = hr->get_next_young_region(); |
| } |
| g1p->revise_young_list_target_length_if_necessary(sampled_rs_lengths); |
| } |
| } |