Thu, 28 Jun 2012 17:03:16 -0400
6995781: Native Memory Tracking (Phase 1)
7151532: DCmd for hotspot native memory tracking
Summary: Implementation of native memory tracking phase 1, which tracks VM native memory usage, and related DCmd
Reviewed-by: acorn, coleenp, fparain
1 /*
2 * Copyright (c) 2003, 2012, 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 */
25 #include "precompiled.hpp"
26 #include "memory/allocation.inline.hpp"
27 #include "memory/filemap.hpp"
28 #include "memory/resourceArea.hpp"
29 #include "oops/oop.inline.hpp"
30 #include "runtime/safepoint.hpp"
31 #include "utilities/dtrace.hpp"
32 #include "utilities/hashtable.hpp"
33 #include "utilities/hashtable.inline.hpp"
36 // This is a generic hashtable, designed to be used for the symbol
37 // and string tables.
38 //
39 // It is implemented as an open hash table with a fixed number of buckets.
40 //
41 // %note:
42 // - HashtableEntrys are allocated in blocks to reduce the space overhead.
44 template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) {
45 BasicHashtableEntry<F>* entry;
47 if (_free_list) {
48 entry = _free_list;
49 _free_list = _free_list->next();
50 } else {
51 if (_first_free_entry + _entry_size >= _end_block) {
52 int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries));
53 int len = _entry_size * block_size;
54 len = 1 << log2_intptr(len); // round down to power of 2
55 assert(len >= _entry_size, "");
56 _first_free_entry = NEW_C_HEAP_ARRAY2(char, len, F, CURRENT_PC);
57 _end_block = _first_free_entry + len;
58 }
59 entry = (BasicHashtableEntry<F>*)_first_free_entry;
60 _first_free_entry += _entry_size;
61 }
63 assert(_entry_size % HeapWordSize == 0, "");
64 entry->set_hash(hashValue);
65 return entry;
66 }
69 template <class T, MEMFLAGS F> HashtableEntry<T, F>* Hashtable<T, F>::new_entry(unsigned int hashValue, T obj) {
70 HashtableEntry<T, F>* entry;
72 entry = (HashtableEntry<T, F>*)BasicHashtable<F>::new_entry(hashValue);
73 entry->set_literal(obj);
74 return entry;
75 }
77 // Check to see if the hashtable is unbalanced. The caller set a flag to
78 // rehash at the next safepoint. If this bucket is 60 times greater than the
79 // expected average bucket length, it's an unbalanced hashtable.
80 // This is somewhat an arbitrary heuristic but if one bucket gets to
81 // rehash_count which is currently 100, there's probably something wrong.
83 template <MEMFLAGS F> bool BasicHashtable<F>::check_rehash_table(int count) {
84 assert(table_size() != 0, "underflow");
85 if (count > (((double)number_of_entries()/(double)table_size())*rehash_multiple)) {
86 // Set a flag for the next safepoint, which should be at some guaranteed
87 // safepoint interval.
88 return true;
89 }
90 return false;
91 }
93 // Create a new table and using alternate hash code, populate the new table
94 // with the existing elements. This can be used to change the hash code
95 // and could in the future change the size of the table.
97 template <class T, MEMFLAGS F> void Hashtable<T, F>::move_to(Hashtable<T, F>* new_table) {
98 int saved_entry_count = BasicHashtable<F>::number_of_entries();
100 // Iterate through the table and create a new entry for the new table
101 for (int i = 0; i < new_table->table_size(); ++i) {
102 for (HashtableEntry<T, F>* p = bucket(i); p != NULL; ) {
103 HashtableEntry<T, F>* next = p->next();
104 T string = p->literal();
105 // Use alternate hashing algorithm on the symbol in the first table
106 unsigned int hashValue = new_hash(string);
107 // Get a new index relative to the new table (can also change size)
108 int index = new_table->hash_to_index(hashValue);
109 p->set_hash(hashValue);
110 // Keep the shared bit in the Hashtable entry to indicate that this entry
111 // can't be deleted. The shared bit is the LSB in the _next field so
112 // walking the hashtable past these entries requires
113 // BasicHashtableEntry::make_ptr() call.
114 bool keep_shared = p->is_shared();
115 unlink_entry(p);
116 new_table->add_entry(index, p);
117 if (keep_shared) {
118 p->set_shared();
119 }
120 p = next;
121 }
122 }
123 // give the new table the free list as well
124 new_table->copy_freelist(this);
125 assert(new_table->number_of_entries() == saved_entry_count, "lost entry on dictionary copy?");
127 // Destroy memory used by the buckets in the hashtable. The memory
128 // for the elements has been used in a new table and is not
129 // destroyed. The memory reuse will benefit resizing the SystemDictionary
130 // to avoid a memory allocation spike at safepoint.
131 BasicHashtable<F>::free_buckets();
132 }
134 template <MEMFLAGS F> void BasicHashtable<F>::free_buckets() {
135 if (NULL != _buckets) {
136 // Don't delete the buckets in the shared space. They aren't
137 // allocated by os::malloc
138 if (!UseSharedSpaces ||
139 !FileMapInfo::current_info()->is_in_shared_space(_buckets)) {
140 FREE_C_HEAP_ARRAY(HashtableBucket, _buckets, F);
141 }
142 _buckets = NULL;
143 }
144 }
147 // Reverse the order of elements in the hash buckets.
149 template <MEMFLAGS F> void BasicHashtable<F>::reverse() {
151 for (int i = 0; i < _table_size; ++i) {
152 BasicHashtableEntry<F>* new_list = NULL;
153 BasicHashtableEntry<F>* p = bucket(i);
154 while (p != NULL) {
155 BasicHashtableEntry<F>* next = p->next();
156 p->set_next(new_list);
157 new_list = p;
158 p = next;
159 }
160 *bucket_addr(i) = new_list;
161 }
162 }
165 // Copy the table to the shared space.
167 template <MEMFLAGS F> void BasicHashtable<F>::copy_table(char** top, char* end) {
169 // Dump the hash table entries.
171 intptr_t *plen = (intptr_t*)(*top);
172 *top += sizeof(*plen);
174 int i;
175 for (i = 0; i < _table_size; ++i) {
176 for (BasicHashtableEntry<F>** p = _buckets[i].entry_addr();
177 *p != NULL;
178 p = (*p)->next_addr()) {
179 if (*top + entry_size() > end) {
180 report_out_of_shared_space(SharedMiscData);
181 }
182 *p = (BasicHashtableEntry<F>*)memcpy(*top, *p, entry_size());
183 *top += entry_size();
184 }
185 }
186 *plen = (char*)(*top) - (char*)plen - sizeof(*plen);
188 // Set the shared bit.
190 for (i = 0; i < _table_size; ++i) {
191 for (BasicHashtableEntry<F>* p = bucket(i); p != NULL; p = p->next()) {
192 p->set_shared();
193 }
194 }
195 }
199 // Reverse the order of elements in the hash buckets.
201 template <class T, MEMFLAGS F> void Hashtable<T, F>::reverse(void* boundary) {
203 for (int i = 0; i < this->table_size(); ++i) {
204 HashtableEntry<T, F>* high_list = NULL;
205 HashtableEntry<T, F>* low_list = NULL;
206 HashtableEntry<T, F>* last_low_entry = NULL;
207 HashtableEntry<T, F>* p = bucket(i);
208 while (p != NULL) {
209 HashtableEntry<T, F>* next = p->next();
210 if ((void*)p->literal() >= boundary) {
211 p->set_next(high_list);
212 high_list = p;
213 } else {
214 p->set_next(low_list);
215 low_list = p;
216 if (last_low_entry == NULL) {
217 last_low_entry = p;
218 }
219 }
220 p = next;
221 }
222 if (low_list != NULL) {
223 *bucket_addr(i) = low_list;
224 last_low_entry->set_next(high_list);
225 } else {
226 *bucket_addr(i) = high_list;
227 }
228 }
229 }
232 // Dump the hash table buckets.
234 template <MEMFLAGS F> void BasicHashtable<F>::copy_buckets(char** top, char* end) {
235 intptr_t len = _table_size * sizeof(HashtableBucket<F>);
236 *(intptr_t*)(*top) = len;
237 *top += sizeof(intptr_t);
239 *(intptr_t*)(*top) = _number_of_entries;
240 *top += sizeof(intptr_t);
242 if (*top + len > end) {
243 report_out_of_shared_space(SharedMiscData);
244 }
245 _buckets = (HashtableBucket<F>*)memcpy(*top, _buckets, len);
246 *top += len;
247 }
250 #ifndef PRODUCT
252 template <class T, MEMFLAGS F> void Hashtable<T, F>::print() {
253 ResourceMark rm;
255 for (int i = 0; i < BasicHashtable<F>::table_size(); i++) {
256 HashtableEntry<T, F>* entry = bucket(i);
257 while(entry != NULL) {
258 tty->print("%d : ", i);
259 entry->literal()->print();
260 tty->cr();
261 entry = entry->next();
262 }
263 }
264 }
267 template <MEMFLAGS F> void BasicHashtable<F>::verify() {
268 int count = 0;
269 for (int i = 0; i < table_size(); i++) {
270 for (BasicHashtableEntry<F>* p = bucket(i); p != NULL; p = p->next()) {
271 ++count;
272 }
273 }
274 assert(count == number_of_entries(), "number of hashtable entries incorrect");
275 }
278 #endif // PRODUCT
281 #ifdef ASSERT
283 template <MEMFLAGS F> void BasicHashtable<F>::verify_lookup_length(double load) {
284 if ((double)_lookup_length / (double)_lookup_count > load * 2.0) {
285 warning("Performance bug: SystemDictionary lookup_count=%d "
286 "lookup_length=%d average=%lf load=%f",
287 _lookup_count, _lookup_length,
288 (double) _lookup_length / _lookup_count, load);
289 }
290 }
292 #endif
293 // Explicitly instantiate these types
294 template class Hashtable<constantPoolOop, mtClass>;
295 template class Hashtable<Symbol*, mtSymbol>;
296 template class Hashtable<klassOop, mtClass>;
297 template class Hashtable<oop, mtClass>;
298 #ifdef SOLARIS
299 template class Hashtable<oop, mtSymbol>;
300 #endif
301 template class Hashtable<oopDesc*, mtSymbol>;
302 template class Hashtable<Symbol*, mtClass>;
303 template class HashtableEntry<Symbol*, mtSymbol>;
304 template class HashtableEntry<Symbol*, mtClass>;
305 template class HashtableEntry<oop, mtSymbol>;
306 template class BasicHashtableEntry<mtSymbol>;
307 template class BasicHashtableEntry<mtCode>;
308 template class BasicHashtable<mtClass>;
309 template class BasicHashtable<mtSymbol>;
310 template class BasicHashtable<mtCode>;
311 template class BasicHashtable<mtInternal>;