Mercurial > hg > truffle
comparison src/share/vm/gc_implementation/g1/concurrentZFThread.cpp @ 342:37f87013dfd8
6711316: Open source the Garbage-First garbage collector
Summary: First mercurial integration of the code for the Garbage-First garbage collector.
Reviewed-by: apetrusenko, iveresov, jmasa, sgoldman, tonyp, ysr
author | ysr |
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date | Thu, 05 Jun 2008 15:57:56 -0700 |
parents | |
children | e1fdf4fd34dc |
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189:0b27f3512f9e | 342:37f87013dfd8 |
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1 /* | |
2 * Copyright 2001-2007 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, | |
20 * CA 95054 USA or visit www.sun.com if you need additional information or | |
21 * have any questions. | |
22 * | |
23 */ | |
24 | |
25 #include "incls/_precompiled.incl" | |
26 #include "incls/_concurrentZFThread.cpp.incl" | |
27 | |
28 // ======= Concurrent Zero-Fill Thread ======== | |
29 | |
30 // The CM thread is created when the G1 garbage collector is used | |
31 | |
32 int ConcurrentZFThread::_region_allocs = 0; | |
33 int ConcurrentZFThread::_sync_zfs = 0; | |
34 int ConcurrentZFThread::_zf_waits = 0; | |
35 int ConcurrentZFThread::_regions_filled = 0; | |
36 | |
37 ConcurrentZFThread::ConcurrentZFThread() : | |
38 ConcurrentGCThread(), | |
39 _co_tracker(G1ZFGroup) | |
40 { | |
41 create_and_start(); | |
42 } | |
43 | |
44 void ConcurrentZFThread::wait_for_ZF_completed(HeapRegion* hr) { | |
45 assert(ZF_mon->owned_by_self(), "Precondition."); | |
46 note_zf_wait(); | |
47 while (hr->zero_fill_state() == HeapRegion::ZeroFilling) { | |
48 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
49 } | |
50 } | |
51 | |
52 void ConcurrentZFThread::processHeapRegion(HeapRegion* hr) { | |
53 assert(!Universe::heap()->is_gc_active(), | |
54 "This should not happen during GC."); | |
55 assert(hr != NULL, "Precondition"); | |
56 // These are unlocked reads, but if this test is successful, then no | |
57 // other thread will attempt this zero filling. Only a GC thread can | |
58 // modify the ZF state of a region whose state is zero-filling, and this | |
59 // should only happen while the ZF thread is locking out GC. | |
60 if (hr->zero_fill_state() == HeapRegion::ZeroFilling | |
61 && hr->zero_filler() == Thread::current()) { | |
62 assert(hr->top() == hr->bottom(), "better be empty!"); | |
63 assert(!hr->isHumongous(), "Only free regions on unclean list."); | |
64 Copy::fill_to_words(hr->bottom(), hr->capacity()/HeapWordSize); | |
65 note_region_filled(); | |
66 } | |
67 } | |
68 | |
69 void ConcurrentZFThread::run() { | |
70 initialize_in_thread(); | |
71 Thread* thr_self = Thread::current(); | |
72 _vtime_start = os::elapsedVTime(); | |
73 wait_for_universe_init(); | |
74 _co_tracker.enable(); | |
75 _co_tracker.start(); | |
76 | |
77 G1CollectedHeap* g1 = G1CollectedHeap::heap(); | |
78 _sts.join(); | |
79 while (!_should_terminate) { | |
80 _sts.leave(); | |
81 | |
82 { | |
83 MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag); | |
84 | |
85 // This local variable will hold a region being zero-filled. This | |
86 // region will neither be on the unclean or zero-filled lists, and | |
87 // will not be available for allocation; thus, we might have an | |
88 // allocation fail, causing a full GC, because of this, but this is a | |
89 // price we will pay. (In future, we might want to make the fact | |
90 // that there's a region being zero-filled apparent to the G1 heap, | |
91 // which could then wait for it in this extreme case...) | |
92 HeapRegion* to_fill; | |
93 | |
94 while (!g1->should_zf() | |
95 || (to_fill = g1->pop_unclean_region_list_locked()) == NULL) | |
96 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
97 while (to_fill->zero_fill_state() == HeapRegion::ZeroFilling) | |
98 ZF_mon->wait(Mutex::_no_safepoint_check_flag); | |
99 | |
100 // So now to_fill is non-NULL and is not ZeroFilling. It might be | |
101 // Allocated or ZeroFilled. (The latter could happen if this thread | |
102 // starts the zero-filling of a region, but a GC intervenes and | |
103 // pushes new regions needing on the front of the filling on the | |
104 // front of the list.) | |
105 | |
106 switch (to_fill->zero_fill_state()) { | |
107 case HeapRegion::Allocated: | |
108 to_fill = NULL; | |
109 break; | |
110 | |
111 case HeapRegion::NotZeroFilled: | |
112 to_fill->set_zero_fill_in_progress(thr_self); | |
113 | |
114 ZF_mon->unlock(); | |
115 _sts.join(); | |
116 processHeapRegion(to_fill); | |
117 _sts.leave(); | |
118 ZF_mon->lock_without_safepoint_check(); | |
119 | |
120 if (to_fill->zero_fill_state() == HeapRegion::ZeroFilling | |
121 && to_fill->zero_filler() == thr_self) { | |
122 to_fill->set_zero_fill_complete(); | |
123 (void)g1->put_free_region_on_list_locked(to_fill); | |
124 } | |
125 break; | |
126 | |
127 case HeapRegion::ZeroFilled: | |
128 (void)g1->put_free_region_on_list_locked(to_fill); | |
129 break; | |
130 | |
131 case HeapRegion::ZeroFilling: | |
132 ShouldNotReachHere(); | |
133 break; | |
134 } | |
135 } | |
136 _vtime_accum = (os::elapsedVTime() - _vtime_start); | |
137 _sts.join(); | |
138 | |
139 _co_tracker.update(); | |
140 } | |
141 _co_tracker.update(false); | |
142 _sts.leave(); | |
143 | |
144 assert(_should_terminate, "just checking"); | |
145 terminate(); | |
146 } | |
147 | |
148 bool ConcurrentZFThread::offer_yield() { | |
149 if (_sts.should_yield()) { | |
150 _sts.yield("Concurrent ZF"); | |
151 return true; | |
152 } else { | |
153 return false; | |
154 } | |
155 } | |
156 | |
157 void ConcurrentZFThread::stop() { | |
158 // it is ok to take late safepoints here, if needed | |
159 MutexLockerEx mu(Terminator_lock); | |
160 _should_terminate = true; | |
161 while (!_has_terminated) { | |
162 Terminator_lock->wait(); | |
163 } | |
164 } | |
165 | |
166 void ConcurrentZFThread::print() { | |
167 gclog_or_tty->print("\"Concurrent ZF Thread\" "); | |
168 Thread::print(); | |
169 gclog_or_tty->cr(); | |
170 } | |
171 | |
172 | |
173 double ConcurrentZFThread::_vtime_accum; | |
174 | |
175 void ConcurrentZFThread::print_summary_info() { | |
176 gclog_or_tty->print("\nConcurrent Zero-Filling:\n"); | |
177 gclog_or_tty->print(" Filled %d regions, used %5.2fs.\n", | |
178 _regions_filled, | |
179 vtime_accum()); | |
180 gclog_or_tty->print(" Of %d region allocs, %d (%5.2f%%) required sync ZF,\n", | |
181 _region_allocs, _sync_zfs, | |
182 (_region_allocs > 0 ? | |
183 (float)_sync_zfs/(float)_region_allocs*100.0 : | |
184 0.0)); | |
185 gclog_or_tty->print(" and %d (%5.2f%%) required a ZF wait.\n", | |
186 _zf_waits, | |
187 (_region_allocs > 0 ? | |
188 (float)_zf_waits/(float)_region_allocs*100.0 : | |
189 0.0)); | |
190 | |
191 } |