rev 1083 : code cache unloading for webrev 091214 rev 1084 : This rev fixes all the print format stuff and resets less counters as recommended by Vladimir. rev 1085 : checkpoint unloading changes on 100107 rev 1086 : use alive_nmethod when traversing code cache rev 1087 : use enum for passing compiler on/off state
1 /* 2 * Copyright 1997-2009 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/_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; 36 37 class MarkActivationClosure: public CodeBlobClosure { 38 public: 39 virtual void do_code_blob(CodeBlob* cb) { 40 // If we see an activation belonging to a non_entrant nmethod, we mark it. 41 if (cb->is_nmethod() && ((nmethod*)cb)->is_not_entrant()) { 42 ((nmethod*)cb)->mark_as_seen_on_stack(); 43 } 44 } 45 }; 46 static MarkActivationClosure mark_activation_closure; 47 48 void NMethodSweeper::sweep() { 49 assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); 50 if (!MethodFlushing) return; 51 52 // No need to synchronize access, since this is always executed at a 53 // safepoint. If we aren't in the middle of scan and a rescan 54 // hasn't been requested then just return. 55 if (_current == NULL && !_rescan) return; 56 57 // Make sure CompiledIC_lock in unlocked, since we might update some 58 // inline caches. If it is, we just bail-out and try later. 59 if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return; 60 61 // Check for restart 62 assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); 63 if (_current == NULL) { 64 _seen = 0; 65 _invocations = NmethodSweepFraction; 66 _current = CodeCache::first(); 67 _traversals += 1; 68 if (PrintMethodFlushing) { 69 tty->print_cr("### Sweep: stack traversal %d", _traversals); 70 } 71 Threads::nmethods_do(&mark_activation_closure); 72 73 // reset the flags since we started a scan from the beginning. 74 _rescan = false; 75 _locked_seen = 0; 76 _not_entrant_seen_on_stack = 0; 77 } 78 79 if (PrintMethodFlushing && Verbose) { 80 tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_blobs(), _invocations); 81 } 82 83 // We want to visit all nmethods after NmethodSweepFraction invocations. 84 // If invocation is 1 we do the rest 85 int todo = CodeCache::nof_blobs(); 86 if (_invocations != 1) { 87 todo = (CodeCache::nof_blobs() - _seen) / _invocations; 88 _invocations--; 89 } 90 91 for(int i = 0; i < todo && _current != NULL; i++) { 92 CodeBlob* next = CodeCache::next(_current); // Read next before we potentially delete current 93 if (_current->is_nmethod()) { 94 process_nmethod((nmethod *)_current); 95 } 96 _seen++; 97 _current = next; 98 } 99 // Because we could stop on a codeBlob other than an nmethod we skip forward 100 // to the next nmethod (if any). codeBlobs other than nmethods can be freed 101 // async to us and make _current invalid while we sleep. 102 while (_current != NULL && !_current->is_nmethod()) { 103 _current = CodeCache::next(_current); 104 } 105 106 if (_current == NULL && !_rescan && (_locked_seen || _not_entrant_seen_on_stack)) { 107 // we've completed a scan without making progress but there were 108 // nmethods we were unable to process either because they were 109 // locked or were still on stack. We don't have to aggresively 110 // clean them up so just stop scanning. We could scan once more 111 // but that complicates the control logic and it's unlikely to 112 // matter much. 113 if (PrintMethodFlushing) { 114 tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep"); 115 } 116 } 117 } 118 119 120 void NMethodSweeper::process_nmethod(nmethod *nm) { 121 // Skip methods that are currently referenced by the VM 122 if (nm->is_locked_by_vm()) { 123 // But still remember to clean-up inline caches for alive nmethods 124 if (nm->is_alive()) { 125 // Clean-up all inline caches that points to zombie/non-reentrant methods 126 nm->cleanup_inline_caches(); 127 } else { 128 _locked_seen++; 129 } 130 return; 131 } 132 133 if (nm->is_zombie()) { 134 // If it is first time, we see nmethod then we mark it. Otherwise, 135 // we reclame it. When we have seen a zombie method twice, we know that 136 // there are no inline caches that referes to it. 137 if (nm->is_marked_for_reclamation()) { 138 assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); 139 if (PrintMethodFlushing && Verbose) { 140 tty->print_cr("### Nmethod 0x%x (marked for reclamation) being flushed", nm); 141 } 142 nm->flush(); 143 } else { 144 if (PrintMethodFlushing && Verbose) { 145 tty->print_cr("### Nmethod 0x%x (zombie) being marked for reclamation", nm); 146 } 147 nm->mark_for_reclamation(); 148 _rescan = true; 149 } 150 } else if (nm->is_not_entrant()) { 151 // If there is no current activations of this method on the 152 // stack we can safely convert it to a zombie method 153 if (nm->can_not_entrant_be_converted()) { 154 if (PrintMethodFlushing && Verbose) { 155 tty->print_cr("### Nmethod 0x%x (not entrant) being made zombie", nm); 156 } 157 nm->make_zombie(); 158 _rescan = true; 159 } else { 160 // Still alive, clean up its inline caches 161 nm->cleanup_inline_caches(); 162 // we coudn't transition this nmethod so don't immediately 163 // request a rescan. If this method stays on the stack for a 164 // long time we don't want to keep rescanning at every safepoint. 165 _not_entrant_seen_on_stack++; 166 } 167 } else if (nm->is_unloaded()) { 168 // Unloaded code, just make it a zombie 169 if (PrintMethodFlushing && Verbose) 170 tty->print_cr("### Nmethod 0x%x (unloaded) being made zombie", nm); 171 if (nm->is_osr_method()) { 172 // No inline caches will ever point to osr methods, so we can just remove it 173 nm->flush(); 174 } else { 175 nm->make_zombie(); 176 _rescan = true; 177 } 178 } else { 179 assert(nm->is_alive(), "should be alive"); 180 // Clean-up all inline caches that points to zombie/non-reentrant methods 181 nm->cleanup_inline_caches(); 182 } 183 } --- EOF ---