Mercurial > hg > graal-jvmci-8
annotate src/share/vm/gc_implementation/g1/concurrentZFThread.cpp @ 2149:7e37af9d69ef
7011379: G1: overly long concurrent marking cycles
Summary: This changeset introduces filtering of SATB buffers at the point when they are about to be enqueued. If this filtering clears enough entries on each buffer, the buffer can then be re-used and not enqueued. This cuts down the number of SATB buffers that need to be processed by the concurrent marking threads.
Reviewed-by: johnc, ysr
| author | tonyp |
|---|---|
| date | Wed, 19 Jan 2011 09:35:17 -0500 |
| parents | f95d63e2154a |
| children |
| rev | line source |
|---|---|
| 342 | 1 /* |
| 1972 | 2 * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved. |
| 342 | 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 * | |
|
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
| 342 | 22 * |
| 23 */ | |
| 24 | |
| 1972 | 25 #include "precompiled.hpp" |
| 26 #include "gc_implementation/g1/concurrentZFThread.hpp" | |
| 27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" | |
| 28 #include "gc_implementation/g1/heapRegion.hpp" | |
| 29 #include "memory/space.inline.hpp" | |
| 30 #include "runtime/mutexLocker.hpp" | |
| 31 #include "utilities/copy.hpp" | |
| 342 | 32 |
| 33 // ======= Concurrent Zero-Fill Thread ======== | |
| 34 | |
| 35 // The CM thread is created when the G1 garbage collector is used | |
| 36 | |
| 37 int ConcurrentZFThread::_region_allocs = 0; | |
| 38 int ConcurrentZFThread::_sync_zfs = 0; | |
| 39 int ConcurrentZFThread::_zf_waits = 0; | |
| 40 int ConcurrentZFThread::_regions_filled = 0; | |
| 41 | |
| 42 ConcurrentZFThread::ConcurrentZFThread() : | |
| 936 | 43 ConcurrentGCThread() |
| 342 | 44 { |
| 45 create_and_start(); | |
| 46 } | |
| 47 | |
| 48 void ConcurrentZFThread::wait_for_ZF_completed(HeapRegion* hr) { | |
| 49 assert(ZF_mon->owned_by_self(), "Precondition."); | |
| 50 note_zf_wait(); | |
| 51 while (hr->zero_fill_state() == HeapRegion::ZeroFilling) { | |
| 52 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
| 53 } | |
| 54 } | |
| 55 | |
| 56 void ConcurrentZFThread::processHeapRegion(HeapRegion* hr) { | |
| 57 assert(!Universe::heap()->is_gc_active(), | |
| 58 "This should not happen during GC."); | |
| 59 assert(hr != NULL, "Precondition"); | |
| 60 // These are unlocked reads, but if this test is successful, then no | |
| 61 // other thread will attempt this zero filling. Only a GC thread can | |
| 62 // modify the ZF state of a region whose state is zero-filling, and this | |
| 63 // should only happen while the ZF thread is locking out GC. | |
| 64 if (hr->zero_fill_state() == HeapRegion::ZeroFilling | |
| 65 && hr->zero_filler() == Thread::current()) { | |
| 66 assert(hr->top() == hr->bottom(), "better be empty!"); | |
| 67 assert(!hr->isHumongous(), "Only free regions on unclean list."); | |
| 68 Copy::fill_to_words(hr->bottom(), hr->capacity()/HeapWordSize); | |
| 69 note_region_filled(); | |
| 70 } | |
| 71 } | |
| 72 | |
| 73 void ConcurrentZFThread::run() { | |
| 74 initialize_in_thread(); | |
| 75 Thread* thr_self = Thread::current(); | |
| 76 _vtime_start = os::elapsedVTime(); | |
| 77 wait_for_universe_init(); | |
| 78 | |
| 79 G1CollectedHeap* g1 = G1CollectedHeap::heap(); | |
| 80 _sts.join(); | |
| 81 while (!_should_terminate) { | |
| 82 _sts.leave(); | |
| 83 | |
| 84 { | |
| 85 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); | |
| 86 | |
| 87 // This local variable will hold a region being zero-filled. This | |
| 88 // region will neither be on the unclean or zero-filled lists, and | |
| 89 // will not be available for allocation; thus, we might have an | |
| 90 // allocation fail, causing a full GC, because of this, but this is a | |
| 91 // price we will pay. (In future, we might want to make the fact | |
| 92 // that there's a region being zero-filled apparent to the G1 heap, | |
| 93 // which could then wait for it in this extreme case...) | |
| 94 HeapRegion* to_fill; | |
| 95 | |
| 96 while (!g1->should_zf() | |
| 97 || (to_fill = g1->pop_unclean_region_list_locked()) == NULL) | |
| 98 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
| 99 while (to_fill->zero_fill_state() == HeapRegion::ZeroFilling) | |
| 100 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
| 101 | |
| 102 // So now to_fill is non-NULL and is not ZeroFilling. It might be | |
| 103 // Allocated or ZeroFilled. (The latter could happen if this thread | |
| 104 // starts the zero-filling of a region, but a GC intervenes and | |
| 105 // pushes new regions needing on the front of the filling on the | |
| 106 // front of the list.) | |
| 107 | |
| 108 switch (to_fill->zero_fill_state()) { | |
| 109 case HeapRegion::Allocated: | |
| 110 to_fill = NULL; | |
| 111 break; | |
| 112 | |
| 113 case HeapRegion::NotZeroFilled: | |
| 114 to_fill->set_zero_fill_in_progress(thr_self); | |
| 115 | |
| 116 ZF_mon->unlock(); | |
| 117 _sts.join(); | |
| 118 processHeapRegion(to_fill); | |
| 119 _sts.leave(); | |
| 120 ZF_mon->lock_without_safepoint_check(); | |
| 121 | |
| 122 if (to_fill->zero_fill_state() == HeapRegion::ZeroFilling | |
| 123 && to_fill->zero_filler() == thr_self) { | |
| 124 to_fill->set_zero_fill_complete(); | |
| 125 (void)g1->put_free_region_on_list_locked(to_fill); | |
| 126 } | |
| 127 break; | |
| 128 | |
| 129 case HeapRegion::ZeroFilled: | |
| 130 (void)g1->put_free_region_on_list_locked(to_fill); | |
| 131 break; | |
| 132 | |
| 133 case HeapRegion::ZeroFilling: | |
| 134 ShouldNotReachHere(); | |
| 135 break; | |
| 136 } | |
| 137 } | |
| 138 _vtime_accum = (os::elapsedVTime() - _vtime_start); | |
| 139 _sts.join(); | |
| 140 } | |
| 141 _sts.leave(); | |
| 142 | |
| 143 assert(_should_terminate, "just checking"); | |
| 144 terminate(); | |
| 145 } | |
| 146 | |
| 147 bool ConcurrentZFThread::offer_yield() { | |
| 148 if (_sts.should_yield()) { | |
| 149 _sts.yield("Concurrent ZF"); | |
| 150 return true; | |
| 151 } else { | |
| 152 return false; | |
| 153 } | |
| 154 } | |
| 155 | |
| 156 void ConcurrentZFThread::stop() { | |
| 157 // it is ok to take late safepoints here, if needed | |
| 158 MutexLockerEx mu(Terminator_lock); | |
| 159 _should_terminate = true; | |
| 160 while (!_has_terminated) { | |
| 161 Terminator_lock->wait(); | |
| 162 } | |
| 163 } | |
| 164 | |
| 1019 | 165 void ConcurrentZFThread::print() const { |
| 166 print_on(tty); | |
| 167 } | |
| 168 | |
| 169 void ConcurrentZFThread::print_on(outputStream* st) const { | |
| 170 st->print("\"G1 Concurrent Zero-Fill Thread\" "); | |
| 171 Thread::print_on(st); | |
| 172 st->cr(); | |
| 342 | 173 } |
| 174 | |
| 175 | |
| 176 double ConcurrentZFThread::_vtime_accum; | |
| 177 | |
| 178 void ConcurrentZFThread::print_summary_info() { | |
| 179 gclog_or_tty->print("\nConcurrent Zero-Filling:\n"); | |
| 180 gclog_or_tty->print(" Filled %d regions, used %5.2fs.\n", | |
| 181 _regions_filled, | |
| 182 vtime_accum()); | |
| 183 gclog_or_tty->print(" Of %d region allocs, %d (%5.2f%%) required sync ZF,\n", | |
| 184 _region_allocs, _sync_zfs, | |
| 185 (_region_allocs > 0 ? | |
| 186 (float)_sync_zfs/(float)_region_allocs*100.0 : | |
| 187 0.0)); | |
| 188 gclog_or_tty->print(" and %d (%5.2f%%) required a ZF wait.\n", | |
| 189 _zf_waits, | |
| 190 (_region_allocs > 0 ? | |
| 191 (float)_zf_waits/(float)_region_allocs*100.0 : | |
| 192 0.0)); | |
| 193 | |
| 194 } |