Mercurial > hg > graal-jvmci-8
annotate src/share/vm/runtime/sweeper.cpp @ 1587:b96a3e44582f
6852873: Reduce safepoint cleanup time
Summary: New optional flags to reduce inflated monitor cleanup times
Reviewed-by: chrisphi, dice
author | acorn |
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date | Thu, 03 Jun 2010 13:21:47 -0400 |
parents | bfe29ec02863 |
children | c18cbe5936b8 |
rev | line source |
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0 | 1 /* |
948 | 2 * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved. |
0 | 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/_sweeper.cpp.incl" | |
27 | |
28 long NMethodSweeper::_traversals = 0; // No. of stack traversals performed | |
29 CodeBlob* NMethodSweeper::_current = NULL; // Current nmethod | |
30 int NMethodSweeper::_seen = 0 ; // No. of blobs we have currently processed in current pass of CodeCache | |
31 int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass | |
32 | |
33 jint NMethodSweeper::_locked_seen = 0; | |
34 jint NMethodSweeper::_not_entrant_seen_on_stack = 0; | |
35 bool NMethodSweeper::_rescan = false; | |
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36 bool NMethodSweeper::_do_sweep = false; |
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37 jint NMethodSweeper::_sweep_started = 0; |
1202 | 38 bool NMethodSweeper::_was_full = false; |
39 jint NMethodSweeper::_advise_to_sweep = 0; | |
40 jlong NMethodSweeper::_last_was_full = 0; | |
41 uint NMethodSweeper::_highest_marked = 0; | |
42 long NMethodSweeper::_was_full_traversal = 0; | |
0 | 43 |
989 | 44 class MarkActivationClosure: public CodeBlobClosure { |
45 public: | |
46 virtual void do_code_blob(CodeBlob* cb) { | |
47 // If we see an activation belonging to a non_entrant nmethod, we mark it. | |
48 if (cb->is_nmethod() && ((nmethod*)cb)->is_not_entrant()) { | |
49 ((nmethod*)cb)->mark_as_seen_on_stack(); | |
50 } | |
51 } | |
52 }; | |
53 static MarkActivationClosure mark_activation_closure; | |
54 | |
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55 void NMethodSweeper::scan_stacks() { |
0 | 56 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); |
57 if (!MethodFlushing) return; | |
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58 _do_sweep = true; |
0 | 59 |
60 // No need to synchronize access, since this is always executed at a | |
61 // safepoint. If we aren't in the middle of scan and a rescan | |
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62 // hasn't been requested then just return. If UseCodeCacheFlushing is on and |
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63 // code cache flushing is in progress, don't skip sweeping to help make progress |
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64 // clearing space in the code cache. |
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65 if ((_current == NULL && !_rescan) && !(UseCodeCacheFlushing && !CompileBroker::should_compile_new_jobs())) { |
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66 _do_sweep = false; |
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67 return; |
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68 } |
0 | 69 |
70 // Make sure CompiledIC_lock in unlocked, since we might update some | |
71 // inline caches. If it is, we just bail-out and try later. | |
72 if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return; | |
73 | |
74 // Check for restart | |
75 assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); | |
76 if (_current == NULL) { | |
77 _seen = 0; | |
78 _invocations = NmethodSweepFraction; | |
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79 _current = CodeCache::first_nmethod(); |
0 | 80 _traversals += 1; |
81 if (PrintMethodFlushing) { | |
82 tty->print_cr("### Sweep: stack traversal %d", _traversals); | |
83 } | |
989 | 84 Threads::nmethods_do(&mark_activation_closure); |
0 | 85 |
86 // reset the flags since we started a scan from the beginning. | |
87 _rescan = false; | |
88 _locked_seen = 0; | |
89 _not_entrant_seen_on_stack = 0; | |
90 } | |
91 | |
1202 | 92 if (UseCodeCacheFlushing) { |
93 if (!CodeCache::needs_flushing()) { | |
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94 // scan_stacks() runs during a safepoint, no race with setters |
1202 | 95 _advise_to_sweep = 0; |
96 } | |
97 | |
98 if (was_full()) { | |
99 // There was some progress so attempt to restart the compiler | |
100 jlong now = os::javaTimeMillis(); | |
101 jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; | |
102 jlong curr_interval = now - _last_was_full; | |
103 if ((!CodeCache::needs_flushing()) && (curr_interval > max_interval)) { | |
104 CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); | |
105 set_was_full(false); | |
106 | |
107 // Update the _last_was_full time so we can tell how fast the | |
108 // code cache is filling up | |
109 _last_was_full = os::javaTimeMillis(); | |
110 | |
111 if (PrintMethodFlushing) { | |
112 tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler", | |
113 CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
114 } | |
115 if (LogCompilation && (xtty != NULL)) { | |
116 ttyLocker ttyl; | |
117 xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", | |
118 CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
119 xtty->stamp(); | |
120 xtty->end_elem(); | |
121 } | |
122 } | |
123 } | |
124 } | |
0 | 125 } |
126 | |
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127 void NMethodSweeper::possibly_sweep() { |
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128 if ((!MethodFlushing) || (!_do_sweep)) return; |
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129 |
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130 if (_invocations > 0) { |
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131 // Only one thread at a time will sweep |
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132 jint old = Atomic::cmpxchg( 1, &_sweep_started, 0 ); |
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133 if (old != 0) { |
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134 return; |
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135 } |
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136 sweep_code_cache(); |
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137 } |
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138 _sweep_started = 0; |
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139 } |
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140 |
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141 void NMethodSweeper::sweep_code_cache() { |
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142 #ifdef ASSERT |
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143 jlong sweep_start; |
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144 if(PrintMethodFlushing) { |
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145 sweep_start = os::javaTimeMillis(); |
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146 } |
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147 #endif |
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148 if (PrintMethodFlushing && Verbose) { |
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149 tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_blobs(), _invocations); |
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150 } |
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151 |
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152 // We want to visit all nmethods after NmethodSweepFraction invocations. |
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153 // If invocation is 1 we do the rest |
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154 int todo = CodeCache::nof_blobs(); |
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155 if (_invocations > 1) { |
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156 todo = (CodeCache::nof_blobs() - _seen) / _invocations; |
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157 } |
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158 |
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159 // Compilers may check to sweep more often than stack scans happen, |
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160 // don't keep trying once it is all scanned |
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161 _invocations--; |
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162 |
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163 assert(!SafepointSynchronize::is_at_safepoint(), "should not be in safepoint when we get here"); |
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164 assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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165 |
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166 { |
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167 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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168 |
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169 for(int i = 0; i < todo && _current != NULL; i++) { |
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170 |
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171 // Since we will give up the CodeCache_lock, always skip ahead to an nmethod. |
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172 // Other blobs can be deleted by other threads |
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173 // Read next before we potentially delete current |
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174 CodeBlob* next = CodeCache::next_nmethod(_current); |
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175 |
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176 // Now ready to process nmethod and give up CodeCache_lock |
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177 { |
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178 MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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179 process_nmethod((nmethod *)_current); |
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180 } |
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181 _seen++; |
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182 _current = next; |
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183 } |
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184 |
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185 // Skip forward to the next nmethod (if any). Code blobs other than nmethods |
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186 // can be freed async to us and make _current invalid while we sleep. |
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187 _current = CodeCache::next_nmethod(_current); |
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188 } |
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189 |
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190 if (_current == NULL && !_rescan && (_locked_seen || _not_entrant_seen_on_stack)) { |
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191 // we've completed a scan without making progress but there were |
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192 // nmethods we were unable to process either because they were |
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193 // locked or were still on stack. We don't have to aggresively |
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194 // clean them up so just stop scanning. We could scan once more |
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195 // but that complicates the control logic and it's unlikely to |
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196 // matter much. |
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197 if (PrintMethodFlushing) { |
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198 tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep"); |
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199 } |
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200 } |
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201 |
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202 #ifdef ASSERT |
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203 if(PrintMethodFlushing) { |
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204 jlong sweep_end = os::javaTimeMillis(); |
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205 tty->print_cr("### sweeper: sweep time(%d): " INT64_FORMAT, _invocations, sweep_end - sweep_start); |
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206 } |
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207 #endif |
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208 } |
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209 |
0 | 210 |
211 void NMethodSweeper::process_nmethod(nmethod *nm) { | |
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212 assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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213 |
0 | 214 // Skip methods that are currently referenced by the VM |
215 if (nm->is_locked_by_vm()) { | |
216 // But still remember to clean-up inline caches for alive nmethods | |
217 if (nm->is_alive()) { | |
218 // Clean-up all inline caches that points to zombie/non-reentrant methods | |
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219 MutexLocker cl(CompiledIC_lock); |
0 | 220 nm->cleanup_inline_caches(); |
221 } else { | |
222 _locked_seen++; | |
223 } | |
224 return; | |
225 } | |
226 | |
227 if (nm->is_zombie()) { | |
228 // If it is first time, we see nmethod then we mark it. Otherwise, | |
229 // we reclame it. When we have seen a zombie method twice, we know that | |
230 // there are no inline caches that referes to it. | |
231 if (nm->is_marked_for_reclamation()) { | |
232 assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); | |
941 | 233 if (PrintMethodFlushing && Verbose) { |
1202 | 234 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm); |
941 | 235 } |
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236 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
0 | 237 nm->flush(); |
238 } else { | |
941 | 239 if (PrintMethodFlushing && Verbose) { |
1202 | 240 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm); |
941 | 241 } |
0 | 242 nm->mark_for_reclamation(); |
243 _rescan = true; | |
244 } | |
245 } else if (nm->is_not_entrant()) { | |
246 // If there is no current activations of this method on the | |
247 // stack we can safely convert it to a zombie method | |
248 if (nm->can_not_entrant_be_converted()) { | |
941 | 249 if (PrintMethodFlushing && Verbose) { |
1202 | 250 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm); |
941 | 251 } |
0 | 252 nm->make_zombie(); |
253 _rescan = true; | |
254 } else { | |
255 // Still alive, clean up its inline caches | |
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256 MutexLocker cl(CompiledIC_lock); |
0 | 257 nm->cleanup_inline_caches(); |
258 // we coudn't transition this nmethod so don't immediately | |
259 // request a rescan. If this method stays on the stack for a | |
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260 // long time we don't want to keep rescanning the code cache. |
0 | 261 _not_entrant_seen_on_stack++; |
262 } | |
263 } else if (nm->is_unloaded()) { | |
264 // Unloaded code, just make it a zombie | |
941 | 265 if (PrintMethodFlushing && Verbose) |
1202 | 266 tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm); |
941 | 267 if (nm->is_osr_method()) { |
0 | 268 // No inline caches will ever point to osr methods, so we can just remove it |
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269 MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
0 | 270 nm->flush(); |
271 } else { | |
272 nm->make_zombie(); | |
273 _rescan = true; | |
274 } | |
275 } else { | |
276 assert(nm->is_alive(), "should be alive"); | |
1202 | 277 |
278 if (UseCodeCacheFlushing) { | |
279 if ((nm->method()->code() != nm) && !(nm->is_locked_by_vm()) && !(nm->is_osr_method()) && | |
280 (_traversals > _was_full_traversal+2) && (((uint)nm->compile_id()) < _highest_marked) && | |
281 CodeCache::needs_flushing()) { | |
282 // This method has not been called since the forced cleanup happened | |
283 nm->make_not_entrant(); | |
284 } | |
285 } | |
286 | |
0 | 287 // Clean-up all inline caches that points to zombie/non-reentrant methods |
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288 MutexLocker cl(CompiledIC_lock); |
0 | 289 nm->cleanup_inline_caches(); |
290 } | |
291 } | |
1202 | 292 |
293 // Code cache unloading: when compilers notice the code cache is getting full, | |
294 // they will call a vm op that comes here. This code attempts to speculatively | |
295 // unload the oldest half of the nmethods (based on the compile job id) by | |
296 // saving the old code in a list in the CodeCache. Then | |
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297 // execution resumes. If a method so marked is not called by the second sweeper |
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298 // stack traversal after the current one, the nmethod will be marked non-entrant and |
1202 | 299 // got rid of by normal sweeping. If the method is called, the methodOop's |
300 // _code field is restored and the methodOop/nmethod | |
301 // go back to their normal state. | |
302 void NMethodSweeper::handle_full_code_cache(bool is_full) { | |
303 // Only the first one to notice can advise us to start early cleaning | |
304 if (!is_full){ | |
305 jint old = Atomic::cmpxchg( 1, &_advise_to_sweep, 0 ); | |
306 if (old != 0) { | |
307 return; | |
308 } | |
309 } | |
310 | |
311 if (is_full) { | |
312 // Since code cache is full, immediately stop new compiles | |
313 bool did_set = CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); | |
314 if (!did_set) { | |
315 // only the first to notice can start the cleaning, | |
316 // others will go back and block | |
317 return; | |
318 } | |
319 set_was_full(true); | |
320 | |
321 // If we run out within MinCodeCacheFlushingInterval of the last unload time, give up | |
322 jlong now = os::javaTimeMillis(); | |
323 jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; | |
324 jlong curr_interval = now - _last_was_full; | |
325 if (curr_interval < max_interval) { | |
326 _rescan = true; | |
327 if (PrintMethodFlushing) { | |
328 tty->print_cr("### handle full too often, turning off compiler"); | |
329 } | |
330 if (LogCompilation && (xtty != NULL)) { | |
331 ttyLocker ttyl; | |
332 xtty->begin_elem("disable_compiler flushing_interval='" UINT64_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", | |
333 curr_interval/1000, CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
334 xtty->stamp(); | |
335 xtty->end_elem(); | |
336 } | |
337 return; | |
338 } | |
339 } | |
340 | |
341 VM_HandleFullCodeCache op(is_full); | |
342 VMThread::execute(&op); | |
343 | |
344 // rescan again as soon as possible | |
345 _rescan = true; | |
346 } | |
347 | |
348 void NMethodSweeper::speculative_disconnect_nmethods(bool is_full) { | |
349 // If there was a race in detecting full code cache, only run | |
350 // one vm op for it or keep the compiler shut off | |
351 | |
352 debug_only(jlong start = os::javaTimeMillis();) | |
353 | |
354 if ((!was_full()) && (is_full)) { | |
355 if (!CodeCache::needs_flushing()) { | |
356 if (PrintMethodFlushing) { | |
357 tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler", | |
358 CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
359 } | |
360 if (LogCompilation && (xtty != NULL)) { | |
361 ttyLocker ttyl; | |
362 xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", | |
363 CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
364 xtty->stamp(); | |
365 xtty->end_elem(); | |
366 } | |
367 CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); | |
368 return; | |
369 } | |
370 } | |
371 | |
372 // Traverse the code cache trying to dump the oldest nmethods | |
373 uint curr_max_comp_id = CompileBroker::get_compilation_id(); | |
374 uint flush_target = ((curr_max_comp_id - _highest_marked) >> 1) + _highest_marked; | |
375 if (PrintMethodFlushing && Verbose) { | |
376 tty->print_cr("### Cleaning code cache: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes", | |
377 CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
378 } | |
379 if (LogCompilation && (xtty != NULL)) { | |
380 ttyLocker ttyl; | |
381 xtty->begin_elem("start_cleaning_code_cache live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", | |
382 CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
383 xtty->stamp(); | |
384 xtty->end_elem(); | |
385 } | |
386 | |
387 nmethod* nm = CodeCache::alive_nmethod(CodeCache::first()); | |
388 jint disconnected = 0; | |
389 jint made_not_entrant = 0; | |
390 while ((nm != NULL)){ | |
391 uint curr_comp_id = nm->compile_id(); | |
392 | |
393 // OSR methods cannot be flushed like this. Also, don't flush native methods | |
394 // since they are part of the JDK in most cases | |
395 if (nm->is_in_use() && (!nm->is_osr_method()) && (!nm->is_locked_by_vm()) && | |
396 (!nm->is_native_method()) && ((curr_comp_id < flush_target))) { | |
397 | |
398 if ((nm->method()->code() == nm)) { | |
399 // This method has not been previously considered for | |
400 // unloading or it was restored already | |
401 CodeCache::speculatively_disconnect(nm); | |
402 disconnected++; | |
403 } else if (nm->is_speculatively_disconnected()) { | |
404 // This method was previously considered for preemptive unloading and was not called since then | |
405 nm->method()->invocation_counter()->decay(); | |
406 nm->method()->backedge_counter()->decay(); | |
407 nm->make_not_entrant(); | |
408 made_not_entrant++; | |
409 } | |
410 | |
411 if (curr_comp_id > _highest_marked) { | |
412 _highest_marked = curr_comp_id; | |
413 } | |
414 } | |
415 nm = CodeCache::alive_nmethod(CodeCache::next(nm)); | |
416 } | |
417 | |
418 if (LogCompilation && (xtty != NULL)) { | |
419 ttyLocker ttyl; | |
420 xtty->begin_elem("stop_cleaning_code_cache disconnected='" UINT32_FORMAT "' made_not_entrant='" UINT32_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", | |
421 disconnected, made_not_entrant, CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); | |
422 xtty->stamp(); | |
423 xtty->end_elem(); | |
424 } | |
425 | |
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426 // Shut off compiler. Sweeper will start over with a new stack scan and |
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427 // traversal cycle and turn it back on if it clears enough space. |
1202 | 428 if (was_full()) { |
429 _last_was_full = os::javaTimeMillis(); | |
430 CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); | |
431 } | |
432 | |
433 // After two more traversals the sweeper will get rid of unrestored nmethods | |
434 _was_full_traversal = _traversals; | |
435 #ifdef ASSERT | |
436 jlong end = os::javaTimeMillis(); | |
437 if(PrintMethodFlushing && Verbose) { | |
438 tty->print_cr("### sweeper: unload time: " INT64_FORMAT, end-start); | |
439 } | |
440 #endif | |
441 } |