| /* |
| * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #include "precompiled.hpp" |
| #include "code/codeCache.hpp" |
| #include "code/compiledIC.hpp" |
| #include "code/icBuffer.hpp" |
| #include "code/nmethod.hpp" |
| #include "compiler/compileBroker.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "oops/method.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/compilationPolicy.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "runtime/orderAccess.inline.hpp" |
| #include "runtime/os.hpp" |
| #include "runtime/sweeper.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "runtime/vm_operations.hpp" |
| #include "trace/tracing.hpp" |
| #include "utilities/events.hpp" |
| #include "utilities/ticks.inline.hpp" |
| #include "utilities/xmlstream.hpp" |
| |
| PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC |
| |
| #ifdef ASSERT |
| |
| #define SWEEP(nm) record_sweep(nm, __LINE__) |
| // Sweeper logging code |
| class SweeperRecord { |
| public: |
| int traversal; |
| int invocation; |
| int compile_id; |
| long traversal_mark; |
| int state; |
| const char* kind; |
| address vep; |
| address uep; |
| int line; |
| |
| void print() { |
| tty->print_cr("traversal = %d invocation = %d compile_id = %d %s uep = " PTR_FORMAT " vep = " |
| PTR_FORMAT " state = %d traversal_mark %d line = %d", |
| traversal, |
| invocation, |
| compile_id, |
| kind == NULL ? "" : kind, |
| uep, |
| vep, |
| state, |
| traversal_mark, |
| line); |
| } |
| }; |
| |
| static int _sweep_index = 0; |
| static SweeperRecord* _records = NULL; |
| |
| void NMethodSweeper::report_events(int id, address entry) { |
| if (_records != NULL) { |
| for (int i = _sweep_index; i < SweeperLogEntries; i++) { |
| if (_records[i].uep == entry || |
| _records[i].vep == entry || |
| _records[i].compile_id == id) { |
| _records[i].print(); |
| } |
| } |
| for (int i = 0; i < _sweep_index; i++) { |
| if (_records[i].uep == entry || |
| _records[i].vep == entry || |
| _records[i].compile_id == id) { |
| _records[i].print(); |
| } |
| } |
| } |
| } |
| |
| void NMethodSweeper::report_events() { |
| if (_records != NULL) { |
| for (int i = _sweep_index; i < SweeperLogEntries; i++) { |
| // skip empty records |
| if (_records[i].vep == NULL) continue; |
| _records[i].print(); |
| } |
| for (int i = 0; i < _sweep_index; i++) { |
| // skip empty records |
| if (_records[i].vep == NULL) continue; |
| _records[i].print(); |
| } |
| } |
| } |
| |
| void NMethodSweeper::record_sweep(nmethod* nm, int line) { |
| if (_records != NULL) { |
| _records[_sweep_index].traversal = _traversals; |
| _records[_sweep_index].traversal_mark = nm->_stack_traversal_mark; |
| _records[_sweep_index].invocation = _sweep_fractions_left; |
| _records[_sweep_index].compile_id = nm->compile_id(); |
| _records[_sweep_index].kind = nm->compile_kind(); |
| _records[_sweep_index].state = nm->_state; |
| _records[_sweep_index].vep = nm->verified_entry_point(); |
| _records[_sweep_index].uep = nm->entry_point(); |
| _records[_sweep_index].line = line; |
| _sweep_index = (_sweep_index + 1) % SweeperLogEntries; |
| } |
| } |
| #else |
| #define SWEEP(nm) |
| #endif |
| |
| nmethod* NMethodSweeper::_current = NULL; // Current nmethod |
| long NMethodSweeper::_traversals = 0; // Stack scan count, also sweep ID. |
| long NMethodSweeper::_total_nof_code_cache_sweeps = 0; // Total number of full sweeps of the code cache |
| long NMethodSweeper::_time_counter = 0; // Virtual time used to periodically invoke sweeper |
| long NMethodSweeper::_last_sweep = 0; // Value of _time_counter when the last sweep happened |
| int NMethodSweeper::_seen = 0; // Nof. nmethod we have currently processed in current pass of CodeCache |
| int NMethodSweeper::_flushed_count = 0; // Nof. nmethods flushed in current sweep |
| int NMethodSweeper::_zombified_count = 0; // Nof. nmethods made zombie in current sweep |
| int NMethodSweeper::_marked_for_reclamation_count = 0; // Nof. nmethods marked for reclaim in current sweep |
| |
| volatile bool NMethodSweeper::_should_sweep = true; // Indicates if we should invoke the sweeper |
| volatile int NMethodSweeper::_sweep_fractions_left = 0; // Nof. invocations left until we are completed with this pass |
| volatile int NMethodSweeper::_sweep_started = 0; // Flag to control conc sweeper |
| volatile int NMethodSweeper::_bytes_changed = 0; // Counts the total nmethod size if the nmethod changed from: |
| // 1) alive -> not_entrant |
| // 2) not_entrant -> zombie |
| // 3) zombie -> marked_for_reclamation |
| int NMethodSweeper::_hotness_counter_reset_val = 0; |
| |
| long NMethodSweeper::_total_nof_methods_reclaimed = 0; // Accumulated nof methods flushed |
| long NMethodSweeper::_total_nof_c2_methods_reclaimed = 0; // Accumulated nof methods flushed |
| size_t NMethodSweeper::_total_flushed_size = 0; // Total number of bytes flushed from the code cache |
| Tickspan NMethodSweeper::_total_time_sweeping; // Accumulated time sweeping |
| Tickspan NMethodSweeper::_total_time_this_sweep; // Total time this sweep |
| Tickspan NMethodSweeper::_peak_sweep_time; // Peak time for a full sweep |
| Tickspan NMethodSweeper::_peak_sweep_fraction_time; // Peak time sweeping one fraction |
| |
| |
| |
| class MarkActivationClosure: public CodeBlobClosure { |
| public: |
| virtual void do_code_blob(CodeBlob* cb) { |
| if (cb->is_nmethod()) { |
| nmethod* nm = (nmethod*)cb; |
| nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val()); |
| // If we see an activation belonging to a non_entrant nmethod, we mark it. |
| if (nm->is_not_entrant()) { |
| nm->mark_as_seen_on_stack(); |
| } |
| } |
| } |
| }; |
| static MarkActivationClosure mark_activation_closure; |
| |
| class SetHotnessClosure: public CodeBlobClosure { |
| public: |
| virtual void do_code_blob(CodeBlob* cb) { |
| if (cb->is_nmethod()) { |
| nmethod* nm = (nmethod*)cb; |
| nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val()); |
| } |
| } |
| }; |
| static SetHotnessClosure set_hotness_closure; |
| |
| |
| int NMethodSweeper::hotness_counter_reset_val() { |
| if (_hotness_counter_reset_val == 0) { |
| _hotness_counter_reset_val = (ReservedCodeCacheSize < M) ? 1 : (ReservedCodeCacheSize / M) * 2; |
| } |
| return _hotness_counter_reset_val; |
| } |
| bool NMethodSweeper::sweep_in_progress() { |
| return (_current != NULL); |
| } |
| |
| // Scans the stacks of all Java threads and marks activations of not-entrant methods. |
| // No need to synchronize access, since 'mark_active_nmethods' is always executed at a |
| // safepoint. |
| void NMethodSweeper::mark_active_nmethods() { |
| assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint"); |
| // If we do not want to reclaim not-entrant or zombie methods there is no need |
| // to scan stacks |
| if (!MethodFlushing) { |
| return; |
| } |
| |
| // Increase time so that we can estimate when to invoke the sweeper again. |
| _time_counter++; |
| |
| // Check for restart |
| assert(CodeCache::find_blob_unsafe(_current) == _current, "Sweeper nmethod cached state invalid"); |
| if (!sweep_in_progress()) { |
| _seen = 0; |
| _sweep_fractions_left = NmethodSweepFraction; |
| _current = CodeCache::first_nmethod(); |
| _traversals += 1; |
| _total_time_this_sweep = Tickspan(); |
| |
| if (PrintMethodFlushing) { |
| tty->print_cr("### Sweep: stack traversal %d", _traversals); |
| } |
| Threads::nmethods_do(&mark_activation_closure); |
| |
| } else { |
| // Only set hotness counter |
| Threads::nmethods_do(&set_hotness_closure); |
| } |
| |
| OrderAccess::storestore(); |
| } |
| /** |
| * This function invokes the sweeper if at least one of the three conditions is met: |
| * (1) The code cache is getting full |
| * (2) There are sufficient state changes in/since the last sweep. |
| * (3) We have not been sweeping for 'some time' |
| */ |
| void NMethodSweeper::possibly_sweep() { |
| assert(JavaThread::current()->thread_state() == _thread_in_vm, "must run in vm mode"); |
| // Only compiler threads are allowed to sweep |
| if (!MethodFlushing || !sweep_in_progress() || !Thread::current()->is_Compiler_thread()) { |
| return; |
| } |
| |
| // If there was no state change while nmethod sweeping, 'should_sweep' will be false. |
| // This is one of the two places where should_sweep can be set to true. The general |
| // idea is as follows: If there is enough free space in the code cache, there is no |
| // need to invoke the sweeper. The following formula (which determines whether to invoke |
| // the sweeper or not) depends on the assumption that for larger ReservedCodeCacheSizes |
| // we need less frequent sweeps than for smaller ReservedCodecCacheSizes. Furthermore, |
| // the formula considers how much space in the code cache is currently used. Here are |
| // some examples that will (hopefully) help in understanding. |
| // |
| // Small ReservedCodeCacheSizes: (e.g., < 16M) We invoke the sweeper every time, since |
| // the result of the division is 0. This |
| // keeps the used code cache size small |
| // (important for embedded Java) |
| // Large ReservedCodeCacheSize : (e.g., 256M + code cache is 10% full). The formula |
| // computes: (256 / 16) - 1 = 15 |
| // As a result, we invoke the sweeper after |
| // 15 invocations of 'mark_active_nmethods. |
| // Large ReservedCodeCacheSize: (e.g., 256M + code Cache is 90% full). The formula |
| // computes: (256 / 16) - 10 = 6. |
| if (!_should_sweep) { |
| const int time_since_last_sweep = _time_counter - _last_sweep; |
| // ReservedCodeCacheSize has an 'unsigned' type. We need a 'signed' type for max_wait_time, |
| // since 'time_since_last_sweep' can be larger than 'max_wait_time'. If that happens using |
| // an unsigned type would cause an underflow (wait_until_next_sweep becomes a large positive |
| // value) that disables the intended periodic sweeps. |
| const int max_wait_time = ReservedCodeCacheSize / (16 * M); |
| double wait_until_next_sweep = max_wait_time - time_since_last_sweep - CodeCache::reverse_free_ratio(); |
| assert(wait_until_next_sweep <= (double)max_wait_time, "Calculation of code cache sweeper interval is incorrect"); |
| |
| if ((wait_until_next_sweep <= 0.0) || !CompileBroker::should_compile_new_jobs()) { |
| _should_sweep = true; |
| } |
| } |
| |
| if (_should_sweep && _sweep_fractions_left > 0) { |
| // Only one thread at a time will sweep |
| jint old = Atomic::cmpxchg( 1, &_sweep_started, 0 ); |
| if (old != 0) { |
| return; |
| } |
| #ifdef ASSERT |
| if (LogSweeper && _records == NULL) { |
| // Create the ring buffer for the logging code |
| _records = NEW_C_HEAP_ARRAY(SweeperRecord, SweeperLogEntries, mtGC); |
| memset(_records, 0, sizeof(SweeperRecord) * SweeperLogEntries); |
| } |
| #endif |
| |
| if (_sweep_fractions_left > 0) { |
| sweep_code_cache(); |
| _sweep_fractions_left--; |
| } |
| |
| // We are done with sweeping the code cache once. |
| if (_sweep_fractions_left == 0) { |
| _total_nof_code_cache_sweeps++; |
| _last_sweep = _time_counter; |
| // Reset flag; temporarily disables sweeper |
| _should_sweep = false; |
| // If there was enough state change, 'possibly_enable_sweeper()' |
| // sets '_should_sweep' to true |
| possibly_enable_sweeper(); |
| // Reset _bytes_changed only if there was enough state change. _bytes_changed |
| // can further increase by calls to 'report_state_change'. |
| if (_should_sweep) { |
| _bytes_changed = 0; |
| } |
| } |
| // Release work, because another compiler thread could continue. |
| OrderAccess::release_store((int*)&_sweep_started, 0); |
| } |
| } |
| |
| void NMethodSweeper::sweep_code_cache() { |
| ResourceMark rm; |
| Ticks sweep_start_counter = Ticks::now(); |
| |
| _flushed_count = 0; |
| _zombified_count = 0; |
| _marked_for_reclamation_count = 0; |
| |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Sweep at %d out of %d. Invocations left: %d", _seen, CodeCache::nof_nmethods(), _sweep_fractions_left); |
| } |
| |
| if (!CompileBroker::should_compile_new_jobs()) { |
| // If we have turned off compilations we might as well do full sweeps |
| // in order to reach the clean state faster. Otherwise the sleeping compiler |
| // threads will slow down sweeping. |
| _sweep_fractions_left = 1; |
| } |
| |
| // We want to visit all nmethods after NmethodSweepFraction |
| // invocations so divide the remaining number of nmethods by the |
| // remaining number of invocations. This is only an estimate since |
| // the number of nmethods changes during the sweep so the final |
| // stage must iterate until it there are no more nmethods. |
| int todo = (CodeCache::nof_nmethods() - _seen) / _sweep_fractions_left; |
| int swept_count = 0; |
| |
| |
| assert(!SafepointSynchronize::is_at_safepoint(), "should not be in safepoint when we get here"); |
| assert(!CodeCache_lock->owned_by_self(), "just checking"); |
| |
| int freed_memory = 0; |
| { |
| MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| |
| // The last invocation iterates until there are no more nmethods |
| for (int i = 0; (i < todo || _sweep_fractions_left == 1) && _current != NULL; i++) { |
| swept_count++; |
| if (SafepointSynchronize::is_synchronizing()) { // Safepoint request |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Sweep at %d out of %d, invocation: %d, yielding to safepoint", _seen, CodeCache::nof_nmethods(), _sweep_fractions_left); |
| } |
| MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| |
| assert(Thread::current()->is_Java_thread(), "should be java thread"); |
| JavaThread* thread = (JavaThread*)Thread::current(); |
| ThreadBlockInVM tbivm(thread); |
| thread->java_suspend_self(); |
| } |
| // Since we will give up the CodeCache_lock, always skip ahead |
| // to the next nmethod. Other blobs can be deleted by other |
| // threads but nmethods are only reclaimed by the sweeper. |
| nmethod* next = CodeCache::next_nmethod(_current); |
| |
| // Now ready to process nmethod and give up CodeCache_lock |
| { |
| MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| freed_memory += process_nmethod(_current); |
| } |
| _seen++; |
| _current = next; |
| } |
| } |
| |
| assert(_sweep_fractions_left > 1 || _current == NULL, "must have scanned the whole cache"); |
| |
| const Ticks sweep_end_counter = Ticks::now(); |
| const Tickspan sweep_time = sweep_end_counter - sweep_start_counter; |
| _total_time_sweeping += sweep_time; |
| _total_time_this_sweep += sweep_time; |
| _peak_sweep_fraction_time = MAX2(sweep_time, _peak_sweep_fraction_time); |
| _total_flushed_size += freed_memory; |
| _total_nof_methods_reclaimed += _flushed_count; |
| |
| EventSweepCodeCache event(UNTIMED); |
| if (event.should_commit()) { |
| event.set_starttime(sweep_start_counter); |
| event.set_endtime(sweep_end_counter); |
| event.set_sweepIndex(_traversals); |
| event.set_sweepFractionIndex(NmethodSweepFraction - _sweep_fractions_left + 1); |
| event.set_sweptCount(swept_count); |
| event.set_flushedCount(_flushed_count); |
| event.set_markedCount(_marked_for_reclamation_count); |
| event.set_zombifiedCount(_zombified_count); |
| event.commit(); |
| } |
| |
| #ifdef ASSERT |
| if(PrintMethodFlushing) { |
| tty->print_cr("### sweeper: sweep time(%d): " |
| INT64_FORMAT, _sweep_fractions_left, (jlong)sweep_time.value()); |
| } |
| #endif |
| |
| if (_sweep_fractions_left == 1) { |
| _peak_sweep_time = MAX2(_peak_sweep_time, _total_time_this_sweep); |
| log_sweep("finished"); |
| } |
| |
| // Sweeper is the only case where memory is released, check here if it |
| // is time to restart the compiler. Only checking if there is a certain |
| // amount of free memory in the code cache might lead to re-enabling |
| // compilation although no memory has been released. For example, there are |
| // cases when compilation was disabled although there is 4MB (or more) free |
| // memory in the code cache. The reason is code cache fragmentation. Therefore, |
| // it only makes sense to re-enable compilation if we have actually freed memory. |
| // Note that typically several kB are released for sweeping 16MB of the code |
| // cache. As a result, 'freed_memory' > 0 to restart the compiler. |
| if (!CompileBroker::should_compile_new_jobs() && (freed_memory > 0)) { |
| CompileBroker::set_should_compile_new_jobs(CompileBroker::run_compilation); |
| log_sweep("restart_compiler"); |
| } |
| } |
| |
| /** |
| * This function updates the sweeper statistics that keep track of nmethods |
| * state changes. If there is 'enough' state change, the sweeper is invoked |
| * as soon as possible. There can be data races on _bytes_changed. The data |
| * races are benign, since it does not matter if we loose a couple of bytes. |
| * In the worst case we call the sweeper a little later. Also, we are guaranteed |
| * to invoke the sweeper if the code cache gets full. |
| */ |
| void NMethodSweeper::report_state_change(nmethod* nm) { |
| _bytes_changed += nm->total_size(); |
| possibly_enable_sweeper(); |
| } |
| |
| /** |
| * Function determines if there was 'enough' state change in the code cache to invoke |
| * the sweeper again. Currently, we determine 'enough' as more than 1% state change in |
| * the code cache since the last sweep. |
| */ |
| void NMethodSweeper::possibly_enable_sweeper() { |
| double percent_changed = ((double)_bytes_changed / (double)ReservedCodeCacheSize) * 100; |
| if (percent_changed > 1.0) { |
| _should_sweep = true; |
| } |
| } |
| |
| class NMethodMarker: public StackObj { |
| private: |
| CompilerThread* _thread; |
| public: |
| NMethodMarker(nmethod* nm) { |
| _thread = CompilerThread::current(); |
| if (!nm->is_zombie() && !nm->is_unloaded()) { |
| // Only expose live nmethods for scanning |
| _thread->set_scanned_nmethod(nm); |
| } |
| } |
| ~NMethodMarker() { |
| _thread->set_scanned_nmethod(NULL); |
| } |
| }; |
| |
| void NMethodSweeper::release_nmethod(nmethod *nm) { |
| // Clean up any CompiledICHolders |
| { |
| ResourceMark rm; |
| MutexLocker ml_patch(CompiledIC_lock); |
| RelocIterator iter(nm); |
| while (iter.next()) { |
| if (iter.type() == relocInfo::virtual_call_type) { |
| CompiledIC::cleanup_call_site(iter.virtual_call_reloc()); |
| } |
| } |
| } |
| |
| MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| nm->flush(); |
| } |
| |
| int NMethodSweeper::process_nmethod(nmethod *nm) { |
| assert(!CodeCache_lock->owned_by_self(), "just checking"); |
| |
| int freed_memory = 0; |
| // Make sure this nmethod doesn't get unloaded during the scan, |
| // since safepoints may happen during acquired below locks. |
| NMethodMarker nmm(nm); |
| SWEEP(nm); |
| |
| // Skip methods that are currently referenced by the VM |
| if (nm->is_locked_by_vm()) { |
| // But still remember to clean-up inline caches for alive nmethods |
| if (nm->is_alive()) { |
| // Clean inline caches that point to zombie/non-entrant methods |
| MutexLocker cl(CompiledIC_lock); |
| nm->cleanup_inline_caches(); |
| SWEEP(nm); |
| } |
| return freed_memory; |
| } |
| |
| if (nm->is_zombie()) { |
| // If it is the first time we see nmethod then we mark it. Otherwise, |
| // we reclaim it. When we have seen a zombie method twice, we know that |
| // there are no inline caches that refer to it. |
| if (nm->is_marked_for_reclamation()) { |
| assert(!nm->is_locked_by_vm(), "must not flush locked nmethods"); |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (marked for reclamation) being flushed", nm->compile_id(), nm); |
| } |
| freed_memory = nm->total_size(); |
| if (nm->is_compiled_by_c2()) { |
| _total_nof_c2_methods_reclaimed++; |
| } |
| release_nmethod(nm); |
| _flushed_count++; |
| } else { |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (zombie) being marked for reclamation", nm->compile_id(), nm); |
| } |
| nm->mark_for_reclamation(); |
| // Keep track of code cache state change |
| _bytes_changed += nm->total_size(); |
| _marked_for_reclamation_count++; |
| SWEEP(nm); |
| } |
| } else if (nm->is_not_entrant()) { |
| // If there are no current activations of this method on the |
| // stack we can safely convert it to a zombie method |
| if (nm->can_convert_to_zombie()) { |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (not entrant) being made zombie", nm->compile_id(), nm); |
| } |
| // Clear ICStubs to prevent back patching stubs of zombie or unloaded |
| // nmethods during the next safepoint (see ICStub::finalize). |
| MutexLocker cl(CompiledIC_lock); |
| nm->clear_ic_stubs(); |
| // Code cache state change is tracked in make_zombie() |
| nm->make_zombie(); |
| _zombified_count++; |
| SWEEP(nm); |
| } else { |
| // Still alive, clean up its inline caches |
| MutexLocker cl(CompiledIC_lock); |
| nm->cleanup_inline_caches(); |
| SWEEP(nm); |
| } |
| } else if (nm->is_unloaded()) { |
| // Unloaded code, just make it a zombie |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Nmethod %3d/" PTR_FORMAT " (unloaded) being made zombie", nm->compile_id(), nm); |
| } |
| if (nm->is_osr_method()) { |
| SWEEP(nm); |
| // No inline caches will ever point to osr methods, so we can just remove it |
| freed_memory = nm->total_size(); |
| if (nm->is_compiled_by_c2()) { |
| _total_nof_c2_methods_reclaimed++; |
| } |
| release_nmethod(nm); |
| _flushed_count++; |
| } else { |
| { |
| // Clean ICs of unloaded nmethods as well because they may reference other |
| // unloaded nmethods that may be flushed earlier in the sweeper cycle. |
| MutexLocker cl(CompiledIC_lock); |
| nm->cleanup_inline_caches(); |
| } |
| // Code cache state change is tracked in make_zombie() |
| nm->make_zombie(); |
| _zombified_count++; |
| SWEEP(nm); |
| } |
| } else { |
| if (UseCodeCacheFlushing) { |
| if (!nm->is_locked_by_vm() && !nm->is_osr_method() && !nm->is_native_method()) { |
| // Do not make native methods and OSR-methods not-entrant |
| nm->dec_hotness_counter(); |
| // Get the initial value of the hotness counter. This value depends on the |
| // ReservedCodeCacheSize |
| int reset_val = hotness_counter_reset_val(); |
| int time_since_reset = reset_val - nm->hotness_counter(); |
| double threshold = -reset_val + (CodeCache::reverse_free_ratio() * NmethodSweepActivity); |
| // The less free space in the code cache we have - the bigger reverse_free_ratio() is. |
| // I.e., 'threshold' increases with lower available space in the code cache and a higher |
| // NmethodSweepActivity. If the current hotness counter - which decreases from its initial |
| // value until it is reset by stack walking - is smaller than the computed threshold, the |
| // corresponding nmethod is considered for removal. |
| if ((NmethodSweepActivity > 0) && (nm->hotness_counter() < threshold) && (time_since_reset > 10)) { |
| // A method is marked as not-entrant if the method is |
| // 1) 'old enough': nm->hotness_counter() < threshold |
| // 2) The method was in_use for a minimum amount of time: (time_since_reset > 10) |
| // The second condition is necessary if we are dealing with very small code cache |
| // sizes (e.g., <10m) and the code cache size is too small to hold all hot methods. |
| // The second condition ensures that methods are not immediately made not-entrant |
| // after compilation. |
| nm->make_not_entrant(); |
| // Code cache state change is tracked in make_not_entrant() |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Nmethod %d/" PTR_FORMAT "made not-entrant: hotness counter %d/%d threshold %f", |
| nm->compile_id(), nm, nm->hotness_counter(), reset_val, threshold); |
| } |
| } |
| } |
| } |
| // Clean-up all inline caches that point to zombie/non-reentrant methods |
| MutexLocker cl(CompiledIC_lock); |
| nm->cleanup_inline_caches(); |
| SWEEP(nm); |
| } |
| return freed_memory; |
| } |
| |
| // Print out some state information about the current sweep and the |
| // state of the code cache if it's requested. |
| void NMethodSweeper::log_sweep(const char* msg, const char* format, ...) { |
| if (PrintMethodFlushing) { |
| ResourceMark rm; |
| stringStream s; |
| // Dump code cache state into a buffer before locking the tty, |
| // because log_state() will use locks causing lock conflicts. |
| CodeCache::log_state(&s); |
| |
| ttyLocker ttyl; |
| tty->print("### sweeper: %s ", msg); |
| if (format != NULL) { |
| va_list ap; |
| va_start(ap, format); |
| tty->vprint(format, ap); |
| va_end(ap); |
| } |
| tty->print_cr("%s", s.as_string()); |
| } |
| |
| if (LogCompilation && (xtty != NULL)) { |
| ResourceMark rm; |
| stringStream s; |
| // Dump code cache state into a buffer before locking the tty, |
| // because log_state() will use locks causing lock conflicts. |
| CodeCache::log_state(&s); |
| |
| ttyLocker ttyl; |
| xtty->begin_elem("sweeper state='%s' traversals='" INTX_FORMAT "' ", msg, (intx)traversal_count()); |
| if (format != NULL) { |
| va_list ap; |
| va_start(ap, format); |
| xtty->vprint(format, ap); |
| va_end(ap); |
| } |
| xtty->print("%s", s.as_string()); |
| xtty->stamp(); |
| xtty->end_elem(); |
| } |
| } |
| |
| void NMethodSweeper::print() { |
| ttyLocker ttyl; |
| tty->print_cr("Code cache sweeper statistics:"); |
| tty->print_cr(" Total sweep time: %1.0lfms", (double)_total_time_sweeping.value()/1000000); |
| tty->print_cr(" Total number of full sweeps: %ld", _total_nof_code_cache_sweeps); |
| tty->print_cr(" Total number of flushed methods: %ld(%ld C2 methods)", _total_nof_methods_reclaimed, |
| _total_nof_c2_methods_reclaimed); |
| tty->print_cr(" Total size of flushed methods: " SIZE_FORMAT "kB", _total_flushed_size/K); |
| } |
