1 /* 2 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "gc/g1/g1CollectedHeap.inline.hpp" 27 #include "gc/g1/g1CollectorPolicy.hpp" 28 #include "gc/g1/g1YoungRemSetSamplingThread.hpp" 29 #include "gc/g1/suspendibleThreadSet.hpp" 30 #include "runtime/mutexLocker.hpp" 31 32 G1YoungRemSetSamplingThread::G1YoungRemSetSamplingThread() : ConcurrentGCThread() { 33 _monitor = new Monitor(Mutex::nonleaf, 34 "G1YoungRemSetSamplingThread monitor", 35 true, 36 Monitor::_safepoint_check_never); 37 38 set_name("G1 Young RemSet Sampling"); 39 create_and_start(); 40 } 41 42 void G1YoungRemSetSamplingThread::sleep_before_next_cycle() { 43 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 44 if (!_should_terminate) { 45 intx waitms = G1ConcRefinementServiceIntervalMillis; // 300, really should be? 46 _monitor->wait(Mutex::_no_safepoint_check_flag, waitms); 47 } 48 } 49 50 void G1YoungRemSetSamplingThread::run_service() { 51 double vtime_start = os::elapsedVTime(); 52 53 while (!_should_terminate) { 54 sample_young_list_rs_lengths(); 55 56 if (os::supports_vtime()) { 57 _vtime_accum = (os::elapsedVTime() - vtime_start); 58 } else { 59 _vtime_accum = 0.0; 60 } 61 62 sleep_before_next_cycle(); 63 } 64 } 65 66 void G1YoungRemSetSamplingThread::stop_service() { 67 MutexLockerEx x(_monitor, Mutex::_no_safepoint_check_flag); 68 _monitor->notify(); 69 } 70 71 void G1YoungRemSetSamplingThread::sample_young_list_rs_lengths() { 72 SuspendibleThreadSetJoiner sts; 73 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 74 G1CollectorPolicy* g1p = g1h->g1_policy(); 75 if (g1p->adaptive_young_list_length()) { 76 int regions_visited = 0; 77 g1h->young_list()->rs_length_sampling_init(); 78 while (g1h->young_list()->rs_length_sampling_more()) { 79 g1h->young_list()->rs_length_sampling_next(); 80 ++regions_visited; 81 82 // we try to yield every time we visit 10 regions 83 if (regions_visited == 10) { 84 if (sts.should_yield()) { 85 sts.yield(); 86 // we just abandon the iteration 87 break; 88 } 89 regions_visited = 0; 90 } 91 } 92 93 g1p->revise_young_list_target_length_if_necessary(); 94 } 95 }