| /* |
| * Copyright (c) 1997, 2018, 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 "jfr/jfrEvents.hpp" |
| #include "logging/log.hpp" |
| #include "logging/logStream.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "oops/method.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/compilationPolicy.hpp" |
| #include "runtime/interfaceSupport.inline.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "runtime/orderAccess.hpp" |
| #include "runtime/os.hpp" |
| #include "runtime/sweeper.hpp" |
| #include "runtime/thread.inline.hpp" |
| #include "runtime/vmOperations.hpp" |
| #include "runtime/vmThread.hpp" |
| #include "utilities/events.hpp" |
| #include "utilities/xmlstream.hpp" |
| |
| #ifdef ASSERT |
| |
| #define SWEEP(nm) record_sweep(nm, __LINE__) |
| // Sweeper logging code |
| class SweeperRecord { |
| public: |
| int traversal; |
| int compile_id; |
| long traversal_mark; |
| int state; |
| const char* kind; |
| address vep; |
| address uep; |
| int line; |
| |
| void print() { |
| tty->print_cr("traversal = %d compile_id = %d %s uep = " PTR_FORMAT " vep = " |
| PTR_FORMAT " state = %d traversal_mark %ld line = %d", |
| traversal, |
| compile_id, |
| kind == NULL ? "" : kind, |
| p2i(uep), |
| p2i(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(CompiledMethod* nm, int line) { |
| if (_records != NULL) { |
| _records[_sweep_index].traversal = _traversals; |
| _records[_sweep_index].traversal_mark = nm->is_nmethod() ? ((nmethod*)nm)->stack_traversal_mark() : 0; |
| _records[_sweep_index].compile_id = nm->compile_id(); |
| _records[_sweep_index].kind = nm->compile_kind(); |
| _records[_sweep_index].state = nm->get_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; |
| } |
| } |
| |
| void NMethodSweeper::init_sweeper_log() { |
| 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); |
| } |
| } |
| #else |
| #define SWEEP(nm) |
| #endif |
| |
| CompiledMethodIterator NMethodSweeper::_current; // Current compiled method |
| 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 |
| |
| volatile bool NMethodSweeper::_should_sweep = false;// Indicates if we should invoke the sweeper |
| volatile bool NMethodSweeper::_force_sweep = false;// Indicates if we should force a sweep |
| volatile int NMethodSweeper::_bytes_changed = 0; // Counts the total nmethod size if the nmethod changed from: |
| // 1) alive -> not_entrant |
| // 2) not_entrant -> zombie |
| 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 |
| |
| Monitor* NMethodSweeper::_stat_lock = new Monitor(Mutex::special, "Sweeper::Statistics", true, Monitor::_safepoint_check_sometimes); |
| |
| class MarkActivationClosure: public CodeBlobClosure { |
| public: |
| virtual void do_code_blob(CodeBlob* cb) { |
| assert(cb->is_nmethod(), "CodeBlob should be 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) { |
| assert(cb->is_nmethod(), "CodeBlob should be 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::wait_for_stack_scanning() { |
| return _current.end(); |
| } |
| |
| /** |
| * 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() { |
| CodeBlobClosure* cl = prepare_mark_active_nmethods(); |
| if (cl != NULL) { |
| Threads::nmethods_do(cl); |
| } |
| } |
| |
| CodeBlobClosure* NMethodSweeper::prepare_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 NULL; |
| } |
| |
| // Increase time so that we can estimate when to invoke the sweeper again. |
| _time_counter++; |
| |
| // Check for restart |
| if (_current.method() != NULL) { |
| if (_current.method()->is_nmethod()) { |
| assert(CodeCache::find_blob_unsafe(_current.method()) == _current.method(), "Sweeper nmethod cached state invalid"); |
| } else if (_current.method()->is_aot()) { |
| assert(CodeCache::find_blob_unsafe(_current.method()->code_begin()) == _current.method(), "Sweeper AOT method cached state invalid"); |
| } else { |
| ShouldNotReachHere(); |
| } |
| } |
| |
| if (wait_for_stack_scanning()) { |
| _seen = 0; |
| _current = CompiledMethodIterator(); |
| // Initialize to first nmethod |
| _current.next(); |
| _traversals += 1; |
| _total_time_this_sweep = Tickspan(); |
| |
| if (PrintMethodFlushing) { |
| tty->print_cr("### Sweep: stack traversal %ld", _traversals); |
| } |
| return &mark_activation_closure; |
| |
| } else { |
| // Only set hotness counter |
| return &set_hotness_closure; |
| } |
| |
| } |
| |
| /** |
| * This function triggers a VM operation that does stack scanning of active |
| * methods. Stack scanning is mandatory for the sweeper to make progress. |
| */ |
| void NMethodSweeper::do_stack_scanning() { |
| assert(!CodeCache_lock->owned_by_self(), "just checking"); |
| if (wait_for_stack_scanning()) { |
| VM_MarkActiveNMethods op; |
| VMThread::execute(&op); |
| _should_sweep = true; |
| } |
| } |
| |
| void NMethodSweeper::sweeper_loop() { |
| bool timeout; |
| while (true) { |
| { |
| ThreadBlockInVM tbivm(JavaThread::current()); |
| MutexLockerEx waiter(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| const long wait_time = 60*60*24 * 1000; |
| timeout = CodeCache_lock->wait(Mutex::_no_safepoint_check_flag, wait_time); |
| } |
| if (!timeout) { |
| possibly_sweep(); |
| } |
| } |
| } |
| |
| /** |
| * Wakes up the sweeper thread to possibly sweep. |
| */ |
| void NMethodSweeper::notify(int code_blob_type) { |
| // Makes sure that we do not invoke the sweeper too often during startup. |
| double start_threshold = 100.0 / (double)StartAggressiveSweepingAt; |
| double aggressive_sweep_threshold = MIN2(start_threshold, 1.1); |
| if (CodeCache::reverse_free_ratio(code_blob_type) >= aggressive_sweep_threshold) { |
| assert_locked_or_safepoint(CodeCache_lock); |
| CodeCache_lock->notify(); |
| } |
| } |
| |
| /** |
| * Wakes up the sweeper thread and forces a sweep. Blocks until it finished. |
| */ |
| void NMethodSweeper::force_sweep() { |
| ThreadBlockInVM tbivm(JavaThread::current()); |
| MutexLockerEx waiter(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| // Request forced sweep |
| _force_sweep = true; |
| while (_force_sweep) { |
| // Notify sweeper that we want to force a sweep and wait for completion. |
| // In case a sweep currently takes place we timeout and try again because |
| // we want to enforce a full sweep. |
| CodeCache_lock->notify(); |
| CodeCache_lock->wait(Mutex::_no_safepoint_check_flag, 1000); |
| } |
| } |
| |
| /** |
| * Handle a safepoint request |
| */ |
| void NMethodSweeper::handle_safepoint_request() { |
| if (SafepointSynchronize::is_synchronizing()) { |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Sweep at %d out of %d, yielding to safepoint", _seen, CodeCache::nmethod_count()); |
| } |
| MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| |
| JavaThread* thread = JavaThread::current(); |
| ThreadBlockInVM tbivm(thread); |
| thread->java_suspend_self(); |
| } |
| } |
| |
| /** |
| * 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"); |
| // 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 - |
| MAX2(CodeCache::reverse_free_ratio(CodeBlobType::MethodProfiled), |
| CodeCache::reverse_free_ratio(CodeBlobType::MethodNonProfiled)); |
| 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; |
| } |
| } |
| |
| // Remember if this was a forced sweep |
| bool forced = _force_sweep; |
| |
| // Force stack scanning if there is only 10% free space in the code cache. |
| // We force stack scanning only if the non-profiled code heap gets full, since critical |
| // allocations go to the non-profiled heap and we must be make sure that there is |
| // enough space. |
| double free_percent = 1 / CodeCache::reverse_free_ratio(CodeBlobType::MethodNonProfiled) * 100; |
| if (free_percent <= StartAggressiveSweepingAt) { |
| do_stack_scanning(); |
| } |
| |
| if (_should_sweep || forced) { |
| init_sweeper_log(); |
| sweep_code_cache(); |
| } |
| |
| // We are done with sweeping the code cache once. |
| _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; |
| } |
| |
| if (forced) { |
| // Notify requester that forced sweep finished |
| assert(_force_sweep, "Should be a forced sweep"); |
| MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| _force_sweep = false; |
| CodeCache_lock->notify(); |
| } |
| } |
| |
| static void post_sweep_event(EventSweepCodeCache* event, |
| const Ticks& start, |
| const Ticks& end, |
| s4 traversals, |
| int swept, |
| int flushed, |
| int zombified) { |
| assert(event != NULL, "invariant"); |
| assert(event->should_commit(), "invariant"); |
| event->set_starttime(start); |
| event->set_endtime(end); |
| event->set_sweepId(traversals); |
| event->set_sweptCount(swept); |
| event->set_flushedCount(flushed); |
| event->set_zombifiedCount(zombified); |
| event->commit(); |
| } |
| |
| void NMethodSweeper::sweep_code_cache() { |
| ResourceMark rm; |
| Ticks sweep_start_counter = Ticks::now(); |
| |
| log_debug(codecache, sweep, start)("CodeCache flushing"); |
| |
| int flushed_count = 0; |
| int zombified_count = 0; |
| int flushed_c2_count = 0; |
| |
| if (PrintMethodFlushing && Verbose) { |
| tty->print_cr("### Sweep at %d out of %d", _seen, CodeCache::nmethod_count()); |
| } |
| |
| 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); |
| |
| while (!_current.end()) { |
| swept_count++; |
| // 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. |
| CompiledMethod* nm = _current.method(); |
| _current.next(); |
| |
| // Now ready to process nmethod and give up CodeCache_lock |
| { |
| MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag); |
| // Save information before potentially flushing the nmethod |
| // Only flushing nmethods so size only matters for them. |
| int size = nm->is_nmethod() ? ((nmethod*)nm)->total_size() : 0; |
| bool is_c2_method = nm->is_compiled_by_c2(); |
| bool is_osr = nm->is_osr_method(); |
| int compile_id = nm->compile_id(); |
| intptr_t address = p2i(nm); |
| const char* state_before = nm->state(); |
| const char* state_after = ""; |
| |
| MethodStateChange type = process_compiled_method(nm); |
| switch (type) { |
| case Flushed: |
| state_after = "flushed"; |
| freed_memory += size; |
| ++flushed_count; |
| if (is_c2_method) { |
| ++flushed_c2_count; |
| } |
| break; |
| case MadeZombie: |
| state_after = "made zombie"; |
| ++zombified_count; |
| break; |
| case None: |
| break; |
| default: |
| ShouldNotReachHere(); |
| } |
| if (PrintMethodFlushing && Verbose && type != None) { |
| tty->print_cr("### %s nmethod %3d/" PTR_FORMAT " (%s) %s", is_osr ? "osr" : "", compile_id, address, state_before, state_after); |
| } |
| } |
| |
| _seen++; |
| handle_safepoint_request(); |
| } |
| } |
| |
| assert(_current.end(), "must have scanned the whole cache"); |
| |
| const Ticks sweep_end_counter = Ticks::now(); |
| const Tickspan sweep_time = sweep_end_counter - sweep_start_counter; |
| { |
| MutexLockerEx mu(_stat_lock, Mutex::_no_safepoint_check_flag); |
| _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; |
| _total_nof_c2_methods_reclaimed += flushed_c2_count; |
| _peak_sweep_time = MAX2(_peak_sweep_time, _total_time_this_sweep); |
| } |
| |
| EventSweepCodeCache event(UNTIMED); |
| if (event.should_commit()) { |
| post_sweep_event(&event, sweep_start_counter, sweep_end_counter, (s4)_traversals, swept_count, flushed_count, zombified_count); |
| } |
| |
| #ifdef ASSERT |
| if(PrintMethodFlushing) { |
| tty->print_cr("### sweeper: sweep time(" JLONG_FORMAT "): ", sweep_time.value()); |
| } |
| #endif |
| |
| Log(codecache, sweep) log; |
| if (log.is_debug()) { |
| LogStream ls(log.debug()); |
| CodeCache::print_summary(&ls, false); |
| } |
| 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.debug("restart compiler"); |
| 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 CompiledMethodMarker: public StackObj { |
| private: |
| CodeCacheSweeperThread* _thread; |
| public: |
| CompiledMethodMarker(CompiledMethod* cm) { |
| JavaThread* current = JavaThread::current(); |
| assert (current->is_Code_cache_sweeper_thread(), "Must be"); |
| _thread = (CodeCacheSweeperThread*)current; |
| if (!cm->is_zombie() && !cm->is_unloaded()) { |
| // Only expose live nmethods for scanning |
| _thread->set_scanned_compiled_method(cm); |
| } |
| } |
| ~CompiledMethodMarker() { |
| _thread->set_scanned_compiled_method(NULL); |
| } |
| }; |
| |
| NMethodSweeper::MethodStateChange NMethodSweeper::process_compiled_method(CompiledMethod* cm) { |
| assert(cm != NULL, "sanity"); |
| assert(!CodeCache_lock->owned_by_self(), "just checking"); |
| |
| MethodStateChange result = None; |
| // Make sure this nmethod doesn't get unloaded during the scan, |
| // since safepoints may happen during acquired below locks. |
| CompiledMethodMarker nmm(cm); |
| SWEEP(cm); |
| |
| // Skip methods that are currently referenced by the VM |
| if (cm->is_locked_by_vm()) { |
| // But still remember to clean-up inline caches for alive nmethods |
| if (cm->is_alive()) { |
| // Clean inline caches that point to zombie/non-entrant/unloaded nmethods |
| MutexLocker cl(CompiledIC_lock); |
| cm->cleanup_inline_caches(); |
| SWEEP(cm); |
| } |
| return result; |
| } |
| |
| if (cm->is_zombie()) { |
| // All inline caches that referred to this nmethod were cleaned in the |
| // previous sweeper cycle. Now flush the nmethod from the code cache. |
| assert(!cm->is_locked_by_vm(), "must not flush locked Compiled Methods"); |
| cm->flush(); |
| assert(result == None, "sanity"); |
| result = Flushed; |
| } else if (cm->is_not_entrant()) { |
| // If there are no current activations of this method on the |
| // stack we can safely convert it to a zombie method |
| OrderAccess::loadload(); // _stack_traversal_mark and _state |
| if (cm->can_convert_to_zombie()) { |
| // Clear ICStubs to prevent back patching stubs of zombie or flushed |
| // nmethods during the next safepoint (see ICStub::finalize). |
| { |
| MutexLocker cl(CompiledIC_lock); |
| cm->clear_ic_callsites(); |
| } |
| // Code cache state change is tracked in make_zombie() |
| cm->make_zombie(); |
| SWEEP(cm); |
| // The nmethod may have been locked by JVMTI after being made zombie (see |
| // JvmtiDeferredEvent::compiled_method_unload_event()). If so, we cannot |
| // flush the osr nmethod directly but have to wait for a later sweeper cycle. |
| if (cm->is_osr_method() && !cm->is_locked_by_vm()) { |
| // No inline caches will ever point to osr methods, so we can just remove it. |
| // Make sure that we unregistered the nmethod with the heap and flushed all |
| // dependencies before removing the nmethod (done in make_zombie()). |
| assert(cm->is_zombie(), "nmethod must be unregistered"); |
| cm->flush(); |
| assert(result == None, "sanity"); |
| result = Flushed; |
| } else { |
| assert(result == None, "sanity"); |
| result = MadeZombie; |
| assert(cm->is_zombie(), "nmethod must be zombie"); |
| } |
| } else { |
| // Still alive, clean up its inline caches |
| MutexLocker cl(CompiledIC_lock); |
| cm->cleanup_inline_caches(); |
| SWEEP(cm); |
| } |
| } else if (cm->is_unloaded()) { |
| // Code is unloaded, so there are no activations on the stack. |
| // Convert the nmethod to zombie or flush it directly in the OSR case. |
| if (cm->is_osr_method()) { |
| SWEEP(cm); |
| // No inline caches will ever point to osr methods, so we can just remove it |
| cm->flush(); |
| assert(result == None, "sanity"); |
| result = Flushed; |
| } else { |
| // Code cache state change is tracked in make_zombie() |
| cm->make_zombie(); |
| SWEEP(cm); |
| assert(result == None, "sanity"); |
| result = MadeZombie; |
| } |
| } else { |
| if (cm->is_nmethod()) { |
| possibly_flush((nmethod*)cm); |
| } |
| // Clean inline caches that point to zombie/non-entrant/unloaded nmethods |
| MutexLocker cl(CompiledIC_lock); |
| cm->cleanup_inline_caches(); |
| SWEEP(cm); |
| } |
| return result; |
| } |
| |
| |
| void NMethodSweeper::possibly_flush(nmethod* nm) { |
| if (UseCodeCacheFlushing) { |
| if (!nm->is_locked_by_vm() && !nm->is_native_method() && !nm->is_not_installed()) { |
| bool make_not_entrant = false; |
| |
| // Do not make native 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(); |
| int code_blob_type = CodeCache::get_code_blob_type(nm); |
| double threshold = -reset_val + (CodeCache::reverse_free_ratio(code_blob_type) * 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 > MinPassesBeforeFlush)) { |
| // 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 > MinPassesBeforeFlush) |
| // 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. |
| make_not_entrant = true; |
| } |
| |
| // The stack-scanning low-cost detection may not see the method was used (which can happen for |
| // flat profiles). Check the age counter for possible data. |
| if (UseCodeAging && make_not_entrant && (nm->is_compiled_by_c2() || nm->is_compiled_by_c1())) { |
| MethodCounters* mc = nm->method()->get_method_counters(Thread::current()); |
| if (mc != NULL) { |
| // Snapshot the value as it's changed concurrently |
| int age = mc->nmethod_age(); |
| if (MethodCounters::is_nmethod_hot(age)) { |
| // The method has gone through flushing, and it became relatively hot that it deopted |
| // before we could take a look at it. Give it more time to appear in the stack traces, |
| // proportional to the number of deopts. |
| MethodData* md = nm->method()->method_data(); |
| if (md != NULL && time_since_reset > (int)(MinPassesBeforeFlush * (md->tenure_traps() + 1))) { |
| // It's been long enough, we still haven't seen it on stack. |
| // Try to flush it, but enable counters the next time. |
| mc->reset_nmethod_age(); |
| } else { |
| make_not_entrant = false; |
| } |
| } else if (MethodCounters::is_nmethod_warm(age)) { |
| // Method has counters enabled, and the method was used within |
| // previous MinPassesBeforeFlush sweeps. Reset the counter. Stay in the existing |
| // compiled state. |
| mc->reset_nmethod_age(); |
| // delay the next check |
| nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val()); |
| make_not_entrant = false; |
| } else if (MethodCounters::is_nmethod_age_unset(age)) { |
| // No counters were used before. Set the counters to the detection |
| // limit value. If the method is going to be used again it will be compiled |
| // with counters that we're going to use for analysis the the next time. |
| mc->reset_nmethod_age(); |
| } else { |
| // Method was totally idle for 10 sweeps |
| // The counter already has the initial value, flush it and may be recompile |
| // later with counters |
| } |
| } |
| } |
| |
| if (make_not_entrant) { |
| 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(), p2i(nm), nm->hotness_counter(), reset_val, threshold); |
| } |
| } |
| } |
| } |
| } |
| |
| // 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(outputStream* out) { |
| ttyLocker ttyl; |
| out = (out == NULL) ? tty : out; |
| out->print_cr("Code cache sweeper statistics:"); |
| out->print_cr(" Total sweep time: %1.0lf ms", (double)_total_time_sweeping.value()/1000000); |
| out->print_cr(" Total number of full sweeps: %ld", _total_nof_code_cache_sweeps); |
| out->print_cr(" Total number of flushed methods: %ld (thereof %ld C2 methods)", _total_nof_methods_reclaimed, |
| _total_nof_c2_methods_reclaimed); |
| out->print_cr(" Total size of flushed methods: " SIZE_FORMAT " kB", _total_flushed_size/K); |
| } |
