Mercurial > hg > truffle
comparison src/share/vm/gc_implementation/g1/g1AllocRegion.cpp @ 2433:abdfc822206f
7023069: G1: Introduce symmetric locking in the slow allocation path
7023151: G1: refactor the code that operates on _cur_alloc_region to be re-used for allocs by the GC threads
7018286: G1: humongous allocation attempts should take the GC locker into account
Summary: First, this change replaces the asymmetric locking scheme in the G1 slow alloc path by a summetric one. Second, it factors out the code that operates on _cur_alloc_region so that it can be re-used for allocations by the GC threads in the future.
Reviewed-by: stefank, brutisso, johnc
author | tonyp |
---|---|
date | Wed, 30 Mar 2011 10:26:59 -0400 |
parents | |
children | f44782f04dd4 |
comparison
equal
deleted
inserted
replaced
2432:455328d90876 | 2433:abdfc822206f |
---|---|
1 /* | |
2 * Copyright (c) 2011, 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/g1AllocRegion.inline.hpp" | |
27 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" | |
28 | |
29 G1CollectedHeap* G1AllocRegion::_g1h = NULL; | |
30 HeapRegion* G1AllocRegion::_dummy_region = NULL; | |
31 | |
32 void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) { | |
33 assert(_dummy_region == NULL, "should be set once"); | |
34 assert(dummy_region != NULL, "pre-condition"); | |
35 assert(dummy_region->free() == 0, "pre-condition"); | |
36 | |
37 // Make sure that any allocation attempt on this region will fail | |
38 // and will not trigger any asserts. | |
39 assert(allocate(dummy_region, 1, false) == NULL, "should fail"); | |
40 assert(par_allocate(dummy_region, 1, false) == NULL, "should fail"); | |
41 assert(allocate(dummy_region, 1, true) == NULL, "should fail"); | |
42 assert(par_allocate(dummy_region, 1, true) == NULL, "should fail"); | |
43 | |
44 _g1h = g1h; | |
45 _dummy_region = dummy_region; | |
46 } | |
47 | |
48 void G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region, | |
49 bool bot_updates) { | |
50 assert(alloc_region != NULL && alloc_region != _dummy_region, | |
51 "pre-condition"); | |
52 | |
53 // Other threads might still be trying to allocate using a CAS out | |
54 // of the region we are trying to retire, as they can do so without | |
55 // holding the lock. So, we first have to make sure that noone else | |
56 // can allocate out of it by doing a maximal allocation. Even if our | |
57 // CAS attempt fails a few times, we'll succeed sooner or later | |
58 // given that failed CAS attempts mean that the region is getting | |
59 // closed to being full. | |
60 size_t free_word_size = alloc_region->free() / HeapWordSize; | |
61 | |
62 // This is the minimum free chunk we can turn into a dummy | |
63 // object. If the free space falls below this, then noone can | |
64 // allocate in this region anyway (all allocation requests will be | |
65 // of a size larger than this) so we won't have to perform the dummy | |
66 // allocation. | |
67 size_t min_word_size_to_fill = CollectedHeap::min_fill_size(); | |
68 | |
69 while (free_word_size >= min_word_size_to_fill) { | |
70 HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates); | |
71 if (dummy != NULL) { | |
72 // If the allocation was successful we should fill in the space. | |
73 CollectedHeap::fill_with_object(dummy, free_word_size); | |
74 alloc_region->set_pre_dummy_top(dummy); | |
75 break; | |
76 } | |
77 | |
78 free_word_size = alloc_region->free() / HeapWordSize; | |
79 // It's also possible that someone else beats us to the | |
80 // allocation and they fill up the region. In that case, we can | |
81 // just get out of the loop. | |
82 } | |
83 assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill, | |
84 "post-condition"); | |
85 } | |
86 | |
87 void G1AllocRegion::retire(bool fill_up) { | |
88 assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly")); | |
89 | |
90 trace("retiring"); | |
91 HeapRegion* alloc_region = _alloc_region; | |
92 if (alloc_region != _dummy_region) { | |
93 // We never have to check whether the active region is empty or not, | |
94 // and potentially free it if it is, given that it's guaranteed that | |
95 // it will never be empty. | |
96 assert(!alloc_region->is_empty(), | |
97 ar_ext_msg(this, "the alloc region should never be empty")); | |
98 | |
99 if (fill_up) { | |
100 fill_up_remaining_space(alloc_region, _bot_updates); | |
101 } | |
102 | |
103 assert(alloc_region->used() >= _used_bytes_before, | |
104 ar_ext_msg(this, "invariant")); | |
105 size_t allocated_bytes = alloc_region->used() - _used_bytes_before; | |
106 retire_region(alloc_region, allocated_bytes); | |
107 _used_bytes_before = 0; | |
108 _alloc_region = _dummy_region; | |
109 } | |
110 trace("retired"); | |
111 } | |
112 | |
113 HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size, | |
114 bool force) { | |
115 assert(_alloc_region == _dummy_region, ar_ext_msg(this, "pre-condition")); | |
116 assert(_used_bytes_before == 0, ar_ext_msg(this, "pre-condition")); | |
117 | |
118 trace("attempting region allocation"); | |
119 HeapRegion* new_alloc_region = allocate_new_region(word_size, force); | |
120 if (new_alloc_region != NULL) { | |
121 new_alloc_region->reset_pre_dummy_top(); | |
122 // Need to do this before the allocation | |
123 _used_bytes_before = new_alloc_region->used(); | |
124 HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates); | |
125 assert(result != NULL, ar_ext_msg(this, "the allocation should succeeded")); | |
126 | |
127 OrderAccess::storestore(); | |
128 // Note that we first perform the allocation and then we store the | |
129 // region in _alloc_region. This is the reason why an active region | |
130 // can never be empty. | |
131 _alloc_region = new_alloc_region; | |
132 trace("region allocation successful"); | |
133 return result; | |
134 } else { | |
135 trace("region allocation failed"); | |
136 return NULL; | |
137 } | |
138 ShouldNotReachHere(); | |
139 } | |
140 | |
141 void G1AllocRegion::fill_in_ext_msg(ar_ext_msg* msg, const char* message) { | |
142 msg->append("[%s] %s b: %s r: "PTR_FORMAT" u: "SIZE_FORMAT, | |
143 _name, message, BOOL_TO_STR(_bot_updates), | |
144 _alloc_region, _used_bytes_before); | |
145 } | |
146 | |
147 void G1AllocRegion::init() { | |
148 trace("initializing"); | |
149 assert(_alloc_region == NULL && _used_bytes_before == 0, | |
150 ar_ext_msg(this, "pre-condition")); | |
151 assert(_dummy_region != NULL, "should have been set"); | |
152 _alloc_region = _dummy_region; | |
153 trace("initialized"); | |
154 } | |
155 | |
156 HeapRegion* G1AllocRegion::release() { | |
157 trace("releasing"); | |
158 HeapRegion* alloc_region = _alloc_region; | |
159 retire(false /* fill_up */); | |
160 assert(_alloc_region == _dummy_region, "post-condition of retire()"); | |
161 _alloc_region = NULL; | |
162 trace("released"); | |
163 return (alloc_region == _dummy_region) ? NULL : alloc_region; | |
164 } | |
165 | |
166 #if G1_ALLOC_REGION_TRACING | |
167 void G1AllocRegion::trace(const char* str, size_t word_size, HeapWord* result) { | |
168 // All the calls to trace that set either just the size or the size | |
169 // and the result are considered part of level 2 tracing and are | |
170 // skipped during level 1 tracing. | |
171 if ((word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) { | |
172 const size_t buffer_length = 128; | |
173 char hr_buffer[buffer_length]; | |
174 char rest_buffer[buffer_length]; | |
175 | |
176 HeapRegion* alloc_region = _alloc_region; | |
177 if (alloc_region == NULL) { | |
178 jio_snprintf(hr_buffer, buffer_length, "NULL"); | |
179 } else if (alloc_region == _dummy_region) { | |
180 jio_snprintf(hr_buffer, buffer_length, "DUMMY"); | |
181 } else { | |
182 jio_snprintf(hr_buffer, buffer_length, | |
183 HR_FORMAT, HR_FORMAT_PARAMS(alloc_region)); | |
184 } | |
185 | |
186 if (G1_ALLOC_REGION_TRACING > 1) { | |
187 if (result != NULL) { | |
188 jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT" "PTR_FORMAT, | |
189 word_size, result); | |
190 } else if (word_size != 0) { | |
191 jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT, word_size); | |
192 } else { | |
193 jio_snprintf(rest_buffer, buffer_length, ""); | |
194 } | |
195 } else { | |
196 jio_snprintf(rest_buffer, buffer_length, ""); | |
197 } | |
198 | |
199 tty->print_cr("[%s] %s : %s %s", _name, hr_buffer, str, rest_buffer); | |
200 } | |
201 } | |
202 #endif // G1_ALLOC_REGION_TRACING | |
203 | |
204 G1AllocRegion::G1AllocRegion(const char* name, | |
205 bool bot_updates) | |
206 : _name(name), _bot_updates(bot_updates), | |
207 _alloc_region(NULL), _used_bytes_before(0) { } | |
208 |