author | twisti |
Fri, 21 May 2010 02:59:24 -0700 | |
changeset 5687 | b862d1f189bd |
parent 5533 | e8d9ff82ec62 |
child 5547 | f4b087cbb361 |
permissions | -rw-r--r-- |
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/* |
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* Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
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* CA 95054 USA or visit www.sun.com if you need additional information or |
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* have any questions. |
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* |
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*/ |
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# include "incls/_precompiled.incl" |
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# include "incls/_sweeper.cpp.incl" |
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long NMethodSweeper::_traversals = 0; // No. of stack traversals performed |
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CodeBlob* NMethodSweeper::_current = NULL; // Current nmethod |
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int NMethodSweeper::_seen = 0 ; // No. of blobs we have currently processed in current pass of CodeCache |
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int NMethodSweeper::_invocations = 0; // No. of invocations left until we are completed with this pass |
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jint NMethodSweeper::_locked_seen = 0; |
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jint NMethodSweeper::_not_entrant_seen_on_stack = 0; |
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bool NMethodSweeper::_rescan = false; |
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bool NMethodSweeper::_do_sweep = false; |
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jint NMethodSweeper::_sweep_started = 0; |
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bool NMethodSweeper::_was_full = false; |
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jint NMethodSweeper::_advise_to_sweep = 0; |
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jlong NMethodSweeper::_last_was_full = 0; |
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uint NMethodSweeper::_highest_marked = 0; |
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long NMethodSweeper::_was_full_traversal = 0; |
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class MarkActivationClosure: public CodeBlobClosure { |
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public: |
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virtual void do_code_blob(CodeBlob* cb) { |
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// If we see an activation belonging to a non_entrant nmethod, we mark it. |
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if (cb->is_nmethod() && ((nmethod*)cb)->is_not_entrant()) { |
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((nmethod*)cb)->mark_as_seen_on_stack(); |
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} |
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} |
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}; |
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static MarkActivationClosure mark_activation_closure; |
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void NMethodSweeper::scan_stacks() { |
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assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); |
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if (!MethodFlushing) return; |
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_do_sweep = true; |
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// No need to synchronize access, since this is always executed at a |
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// safepoint. If we aren't in the middle of scan and a rescan |
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// hasn't been requested then just return. If UseCodeCacheFlushing is on and |
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// code cache flushing is in progress, don't skip sweeping to help make progress |
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// clearing space in the code cache. |
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if ((_current == NULL && !_rescan) && !(UseCodeCacheFlushing && !CompileBroker::should_compile_new_jobs())) { |
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_do_sweep = false; |
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return; |
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} |
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// Make sure CompiledIC_lock in unlocked, since we might update some |
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// inline caches. If it is, we just bail-out and try later. |
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if (CompiledIC_lock->is_locked() || Patching_lock->is_locked()) return; |
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// Check for restart |
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assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); |
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if (_current == NULL) { |
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_seen = 0; |
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_invocations = NmethodSweepFraction; |
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_current = CodeCache::first_nmethod(); |
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_traversals += 1; |
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if (PrintMethodFlushing) { |
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tty->print_cr("### Sweep: stack traversal %d", _traversals); |
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} |
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Threads::nmethods_do(&mark_activation_closure); |
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// reset the flags since we started a scan from the beginning. |
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_rescan = false; |
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_locked_seen = 0; |
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_not_entrant_seen_on_stack = 0; |
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} |
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if (UseCodeCacheFlushing) { |
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if (!CodeCache::needs_flushing()) { |
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// scan_stacks() runs during a safepoint, no race with setters |
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_advise_to_sweep = 0; |
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} |
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if (was_full()) { |
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// There was some progress so attempt to restart the compiler |
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jlong now = os::javaTimeMillis(); |
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jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; |
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jlong curr_interval = now - _last_was_full; |
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if ((!CodeCache::needs_flushing()) && (curr_interval > max_interval)) { |
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CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); |
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set_was_full(false); |
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// Update the _last_was_full time so we can tell how fast the |
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// code cache is filling up |
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_last_was_full = os::javaTimeMillis(); |
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if (PrintMethodFlushing) { |
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tty->print_cr("### sweeper: Live blobs:" UINT32_FORMAT "/Free code cache:" SIZE_FORMAT " bytes, restarting compiler", |
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); |
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} |
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if (LogCompilation && (xtty != NULL)) { |
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ttyLocker ttyl; |
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xtty->begin_elem("restart_compiler live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", |
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CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); |
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xtty->stamp(); |
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xtty->end_elem(); |
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} |
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} |
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} |
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} |
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} |
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void NMethodSweeper::possibly_sweep() { |
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if ((!MethodFlushing) || (!_do_sweep)) return; |
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if (_invocations > 0) { |
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// Only one thread at a time will sweep |
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jint old = Atomic::cmpxchg( 1, &_sweep_started, 0 ); |
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if (old != 0) { |
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return; |
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} |
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sweep_code_cache(); |
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} |
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_sweep_started = 0; |
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} |
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void NMethodSweeper::sweep_code_cache() { |
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#ifdef ASSERT |
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jlong sweep_start; |
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if(PrintMethodFlushing) { |
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sweep_start = os::javaTimeMillis(); |
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} |
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#endif |
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if (PrintMethodFlushing && Verbose) { |
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tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_blobs(), _invocations); |
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} |
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// We want to visit all nmethods after NmethodSweepFraction invocations. |
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// If invocation is 1 we do the rest |
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int todo = CodeCache::nof_blobs(); |
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if (_invocations > 1) { |
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todo = (CodeCache::nof_blobs() - _seen) / _invocations; |
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} |
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// Compilers may check to sweep more often than stack scans happen, |
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// don't keep trying once it is all scanned |
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_invocations--; |
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assert(!SafepointSynchronize::is_at_safepoint(), "should not be in safepoint when we get here"); |
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assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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|
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{ |
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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for(int i = 0; i < todo && _current != NULL; i++) { |
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// Since we will give up the CodeCache_lock, always skip ahead to an nmethod. |
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// Other blobs can be deleted by other threads |
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// Read next before we potentially delete current |
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CodeBlob* next = CodeCache::next_nmethod(_current); |
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// Now ready to process nmethod and give up CodeCache_lock |
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{ |
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MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
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process_nmethod((nmethod *)_current); |
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} |
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_seen++; |
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_current = next; |
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} |
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// Skip forward to the next nmethod (if any). Code blobs other than nmethods |
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// can be freed async to us and make _current invalid while we sleep. |
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_current = CodeCache::next_nmethod(_current); |
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} |
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if (_current == NULL && !_rescan && (_locked_seen || _not_entrant_seen_on_stack)) { |
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// we've completed a scan without making progress but there were |
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// nmethods we were unable to process either because they were |
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// locked or were still on stack. We don't have to aggresively |
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// clean them up so just stop scanning. We could scan once more |
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// but that complicates the control logic and it's unlikely to |
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// matter much. |
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if (PrintMethodFlushing) { |
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tty->print_cr("### Couldn't make progress on some nmethods so stopping sweep"); |
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} |
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} |
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#ifdef ASSERT |
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if(PrintMethodFlushing) { |
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jlong sweep_end = os::javaTimeMillis(); |
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tty->print_cr("### sweeper: sweep time(%d): " INT64_FORMAT, _invocations, sweep_end - sweep_start); |
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} |
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#endif |
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} |
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209 |
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1 | 210 |
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211 |
void NMethodSweeper::process_nmethod(nmethod *nm) { |
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assert(!CodeCache_lock->owned_by_self(), "just checking"); |
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213 |
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1 | 214 |
// Skip methods that are currently referenced by the VM |
215 |
if (nm->is_locked_by_vm()) { |
|
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// But still remember to clean-up inline caches for alive nmethods |
|
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if (nm->is_alive()) { |
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// Clean-up all inline caches that points to zombie/non-reentrant methods |
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MutexLocker cl(CompiledIC_lock); |
1 | 220 |
nm->cleanup_inline_caches(); |
221 |
} else { |
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_locked_seen++; |
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} |
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return; |
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} |
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226 |
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227 |
if (nm->is_zombie()) { |
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// If it is first time, we see nmethod then we mark it. Otherwise, |
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// we reclame it. When we have seen a zombie method twice, we know that |
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// there are no inline caches that referes to it. |
|
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if (nm->is_marked_for_reclamation()) { |
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assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); |
|
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if (PrintMethodFlushing && Verbose) { |
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tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm); |
3696 | 235 |
} |
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
1 | 237 |
nm->flush(); |
238 |
} else { |
|
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if (PrintMethodFlushing && Verbose) { |
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tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm); |
3696 | 241 |
} |
1 | 242 |
nm->mark_for_reclamation(); |
243 |
_rescan = true; |
|
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} |
|
245 |
} else if (nm->is_not_entrant()) { |
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// If there is no current activations of this method on the |
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// stack we can safely convert it to a zombie method |
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if (nm->can_not_entrant_be_converted()) { |
|
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if (PrintMethodFlushing && Verbose) { |
4750 | 250 |
tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm); |
3696 | 251 |
} |
1 | 252 |
nm->make_zombie(); |
253 |
_rescan = true; |
|
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} else { |
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// Still alive, clean up its inline caches |
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MutexLocker cl(CompiledIC_lock); |
1 | 257 |
nm->cleanup_inline_caches(); |
258 |
// we coudn't transition this nmethod so don't immediately |
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// request a rescan. If this method stays on the stack for a |
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// long time we don't want to keep rescanning the code cache. |
1 | 261 |
_not_entrant_seen_on_stack++; |
262 |
} |
|
263 |
} else if (nm->is_unloaded()) { |
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// Unloaded code, just make it a zombie |
|
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if (PrintMethodFlushing && Verbose) |
4750 | 266 |
tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm); |
3696 | 267 |
if (nm->is_osr_method()) { |
1 | 268 |
// No inline caches will ever point to osr methods, so we can just remove it |
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
1 | 270 |
nm->flush(); |
271 |
} else { |
|
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nm->make_zombie(); |
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_rescan = true; |
|
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} |
|
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} else { |
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assert(nm->is_alive(), "should be alive"); |
|
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if (UseCodeCacheFlushing) { |
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if ((nm->method()->code() != nm) && !(nm->is_locked_by_vm()) && !(nm->is_osr_method()) && |
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(_traversals > _was_full_traversal+2) && (((uint)nm->compile_id()) < _highest_marked) && |
|
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CodeCache::needs_flushing()) { |
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// This method has not been called since the forced cleanup happened |
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nm->make_not_entrant(); |
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} |
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} |
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||
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// Clean-up all inline caches that points to zombie/non-reentrant methods |
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MutexLocker cl(CompiledIC_lock); |
1 | 289 |
nm->cleanup_inline_caches(); |
290 |
} |
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291 |
} |
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// Code cache unloading: when compilers notice the code cache is getting full, |
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// they will call a vm op that comes here. This code attempts to speculatively |
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// unload the oldest half of the nmethods (based on the compile job id) by |
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// saving the old code in a list in the CodeCache. Then |
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// execution resumes. If a method so marked is not called by the second sweeper |
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// stack traversal after the current one, the nmethod will be marked non-entrant and |
4750 | 299 |
// got rid of by normal sweeping. If the method is called, the methodOop's |
300 |
// _code field is restored and the methodOop/nmethod |
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// go back to their normal state. |
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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){ |
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305 |
jint old = Atomic::cmpxchg( 1, &_advise_to_sweep, 0 ); |
|
306 |
if (old != 0) { |
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307 |
return; |
|
308 |
} |
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309 |
} |
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310 |
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311 |
if (is_full) { |
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312 |
// Since code cache is full, immediately stop new compiles |
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313 |
bool did_set = CompileBroker::set_should_compile_new_jobs(CompileBroker::stop_compilation); |
|
314 |
if (!did_set) { |
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// only the first to notice can start the cleaning, |
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// others will go back and block |
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return; |
|
318 |
} |
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set_was_full(true); |
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320 |
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// If we run out within MinCodeCacheFlushingInterval of the last unload time, give up |
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jlong now = os::javaTimeMillis(); |
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323 |
jlong max_interval = (jlong)MinCodeCacheFlushingInterval * (jlong)1000; |
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324 |
jlong curr_interval = now - _last_was_full; |
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325 |
if (curr_interval < max_interval) { |
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_rescan = true; |
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327 |
if (PrintMethodFlushing) { |
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328 |
tty->print_cr("### handle full too often, turning off compiler"); |
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329 |
} |
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330 |
if (LogCompilation && (xtty != NULL)) { |
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331 |
ttyLocker ttyl; |
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332 |
xtty->begin_elem("disable_compiler flushing_interval='" UINT64_FORMAT "' live_blobs='" UINT32_FORMAT "' free_code_cache='" SIZE_FORMAT "'", |
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curr_interval/1000, CodeCache::nof_blobs(), CodeCache::unallocated_capacity()); |
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334 |
xtty->stamp(); |
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335 |
xtty->end_elem(); |
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336 |
} |
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337 |
return; |
|
338 |
} |
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339 |
} |
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340 |
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341 |
VM_HandleFullCodeCache op(is_full); |
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342 |
VMThread::execute(&op); |
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343 |
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344 |
// rescan again as soon as possible |
|
345 |
_rescan = true; |
|
346 |
} |
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347 |
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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 |
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351 |
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352 |
debug_only(jlong start = os::javaTimeMillis();) |
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353 |
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354 |
if ((!was_full()) && (is_full)) { |
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355 |
if (!CodeCache::needs_flushing()) { |
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if (PrintMethodFlushing) { |
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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 |
} |
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360 |
if (LogCompilation && (xtty != NULL)) { |
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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 |
} |
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371 |
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// 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 |
} |
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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. |
4750 | 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 |
} |