1 /* |
|
2 * Copyright (c) 2001, 2010, 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_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" |
|
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() : |
|
43 ConcurrentGCThread() |
|
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 |
|
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(); |
|
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 } |
|