804 lines
31 KiB
C++
804 lines
31 KiB
C++
/*
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* Copyright (c) 1997, 2016, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "code/codeCache.hpp"
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#include "code/compiledIC.hpp"
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#include "code/icBuffer.hpp"
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#include "code/nmethod.hpp"
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#include "compiler/compileBroker.hpp"
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#include "memory/resourceArea.hpp"
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#include "oops/method.hpp"
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#include "runtime/atomic.inline.hpp"
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#include "runtime/compilationPolicy.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/orderAccess.inline.hpp"
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#include "runtime/os.hpp"
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#include "runtime/sweeper.hpp"
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#include "runtime/thread.inline.hpp"
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#include "runtime/vm_operations.hpp"
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#include "trace/tracing.hpp"
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#include "utilities/events.hpp"
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#include "utilities/ticks.inline.hpp"
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#include "utilities/xmlstream.hpp"
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#ifdef ASSERT
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#define SWEEP(nm) record_sweep(nm, __LINE__)
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// Sweeper logging code
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class SweeperRecord {
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public:
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int traversal;
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int compile_id;
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long traversal_mark;
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int state;
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const char* kind;
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address vep;
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address uep;
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int line;
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void print() {
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tty->print_cr("traversal = %d compile_id = %d %s uep = " PTR_FORMAT " vep = "
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PTR_FORMAT " state = %d traversal_mark %ld line = %d",
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traversal,
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compile_id,
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kind == NULL ? "" : kind,
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p2i(uep),
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p2i(vep),
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state,
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traversal_mark,
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line);
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}
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};
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static int _sweep_index = 0;
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static SweeperRecord* _records = NULL;
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void NMethodSweeper::report_events(int id, address entry) {
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if (_records != NULL) {
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for (int i = _sweep_index; i < SweeperLogEntries; i++) {
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if (_records[i].uep == entry ||
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_records[i].vep == entry ||
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_records[i].compile_id == id) {
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_records[i].print();
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}
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}
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for (int i = 0; i < _sweep_index; i++) {
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if (_records[i].uep == entry ||
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_records[i].vep == entry ||
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_records[i].compile_id == id) {
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_records[i].print();
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}
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}
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}
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}
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void NMethodSweeper::report_events() {
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if (_records != NULL) {
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for (int i = _sweep_index; i < SweeperLogEntries; i++) {
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// skip empty records
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if (_records[i].vep == NULL) continue;
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_records[i].print();
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}
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for (int i = 0; i < _sweep_index; i++) {
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// skip empty records
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if (_records[i].vep == NULL) continue;
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_records[i].print();
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}
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}
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}
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void NMethodSweeper::record_sweep(nmethod* nm, int line) {
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if (_records != NULL) {
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_records[_sweep_index].traversal = _traversals;
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_records[_sweep_index].traversal_mark = nm->_stack_traversal_mark;
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_records[_sweep_index].compile_id = nm->compile_id();
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_records[_sweep_index].kind = nm->compile_kind();
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_records[_sweep_index].state = nm->_state;
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_records[_sweep_index].vep = nm->verified_entry_point();
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_records[_sweep_index].uep = nm->entry_point();
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_records[_sweep_index].line = line;
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_sweep_index = (_sweep_index + 1) % SweeperLogEntries;
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}
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}
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void NMethodSweeper::init_sweeper_log() {
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if (LogSweeper && _records == NULL) {
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// Create the ring buffer for the logging code
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_records = NEW_C_HEAP_ARRAY(SweeperRecord, SweeperLogEntries, mtGC);
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memset(_records, 0, sizeof(SweeperRecord) * SweeperLogEntries);
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}
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}
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#else
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#define SWEEP(nm)
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#endif
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NMethodIterator NMethodSweeper::_current; // Current nmethod
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long NMethodSweeper::_traversals = 0; // Stack scan count, also sweep ID.
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long NMethodSweeper::_total_nof_code_cache_sweeps = 0; // Total number of full sweeps of the code cache
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long NMethodSweeper::_time_counter = 0; // Virtual time used to periodically invoke sweeper
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long NMethodSweeper::_last_sweep = 0; // Value of _time_counter when the last sweep happened
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int NMethodSweeper::_seen = 0; // Nof. nmethod we have currently processed in current pass of CodeCache
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volatile bool NMethodSweeper::_should_sweep = true; // Indicates if we should invoke the sweeper
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volatile bool NMethodSweeper::_force_sweep = false;// Indicates if we should force a sweep
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volatile int NMethodSweeper::_bytes_changed = 0; // Counts the total nmethod size if the nmethod changed from:
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// 1) alive -> not_entrant
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// 2) not_entrant -> zombie
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int NMethodSweeper::_hotness_counter_reset_val = 0;
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long NMethodSweeper::_total_nof_methods_reclaimed = 0; // Accumulated nof methods flushed
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long NMethodSweeper::_total_nof_c2_methods_reclaimed = 0; // Accumulated nof methods flushed
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size_t NMethodSweeper::_total_flushed_size = 0; // Total number of bytes flushed from the code cache
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Tickspan NMethodSweeper::_total_time_sweeping; // Accumulated time sweeping
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Tickspan NMethodSweeper::_total_time_this_sweep; // Total time this sweep
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Tickspan NMethodSweeper::_peak_sweep_time; // Peak time for a full sweep
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Tickspan NMethodSweeper::_peak_sweep_fraction_time; // Peak time sweeping one fraction
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Monitor* NMethodSweeper::_stat_lock = new Monitor(Mutex::special, "Sweeper::Statistics", true, Monitor::_safepoint_check_sometimes);
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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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assert(cb->is_nmethod(), "CodeBlob should be nmethod");
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nmethod* nm = (nmethod*)cb;
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nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val());
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// If we see an activation belonging to a non_entrant nmethod, we mark it.
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if (nm->is_not_entrant()) {
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nm->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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class SetHotnessClosure: public CodeBlobClosure {
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public:
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virtual void do_code_blob(CodeBlob* cb) {
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assert(cb->is_nmethod(), "CodeBlob should be nmethod");
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nmethod* nm = (nmethod*)cb;
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nm->set_hotness_counter(NMethodSweeper::hotness_counter_reset_val());
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}
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};
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static SetHotnessClosure set_hotness_closure;
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int NMethodSweeper::hotness_counter_reset_val() {
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if (_hotness_counter_reset_val == 0) {
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_hotness_counter_reset_val = (ReservedCodeCacheSize < M) ? 1 : (ReservedCodeCacheSize / M) * 2;
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}
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return _hotness_counter_reset_val;
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}
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bool NMethodSweeper::wait_for_stack_scanning() {
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return _current.end();
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}
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/**
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* Scans the stacks of all Java threads and marks activations of not-entrant methods.
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* No need to synchronize access, since 'mark_active_nmethods' is always executed at a
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* safepoint.
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*/
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void NMethodSweeper::mark_active_nmethods() {
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assert(SafepointSynchronize::is_at_safepoint(), "must be executed at a safepoint");
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// If we do not want to reclaim not-entrant or zombie methods there is no need
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// to scan stacks
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if (!MethodFlushing) {
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return;
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}
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// Increase time so that we can estimate when to invoke the sweeper again.
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_time_counter++;
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// Check for restart
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assert(CodeCache::find_blob_unsafe(_current.method()) == _current.method(), "Sweeper nmethod cached state invalid");
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if (wait_for_stack_scanning()) {
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_seen = 0;
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_current = NMethodIterator();
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// Initialize to first nmethod
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_current.next();
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_traversals += 1;
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_total_time_this_sweep = Tickspan();
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if (PrintMethodFlushing) {
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tty->print_cr("### Sweep: stack traversal %ld", _traversals);
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}
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Threads::nmethods_do(&mark_activation_closure);
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} else {
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// Only set hotness counter
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Threads::nmethods_do(&set_hotness_closure);
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}
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OrderAccess::storestore();
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}
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/**
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* This function triggers a VM operation that does stack scanning of active
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* methods. Stack scanning is mandatory for the sweeper to make progress.
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*/
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void NMethodSweeper::do_stack_scanning() {
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assert(!CodeCache_lock->owned_by_self(), "just checking");
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if (wait_for_stack_scanning()) {
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VM_MarkActiveNMethods op;
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VMThread::execute(&op);
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_should_sweep = true;
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}
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}
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void NMethodSweeper::sweeper_loop() {
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bool timeout;
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while (true) {
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{
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ThreadBlockInVM tbivm(JavaThread::current());
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MutexLockerEx waiter(CodeCache_lock, Mutex::_no_safepoint_check_flag);
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const long wait_time = 60*60*24 * 1000;
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timeout = CodeCache_lock->wait(Mutex::_no_safepoint_check_flag, wait_time);
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}
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if (!timeout) {
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possibly_sweep();
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}
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}
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}
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/**
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* Wakes up the sweeper thread to possibly sweep.
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*/
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void NMethodSweeper::notify(int code_blob_type) {
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// Makes sure that we do not invoke the sweeper too often during startup.
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double start_threshold = 100.0 / (double)StartAggressiveSweepingAt;
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double aggressive_sweep_threshold = MIN2(start_threshold, 1.1);
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if (CodeCache::reverse_free_ratio(code_blob_type) >= aggressive_sweep_threshold) {
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assert_locked_or_safepoint(CodeCache_lock);
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CodeCache_lock->notify();
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}
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}
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/**
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* Wakes up the sweeper thread and forces a sweep. Blocks until it finished.
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*/
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void NMethodSweeper::force_sweep() {
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ThreadBlockInVM tbivm(JavaThread::current());
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MutexLockerEx waiter(CodeCache_lock, Mutex::_no_safepoint_check_flag);
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// Request forced sweep
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_force_sweep = true;
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while (_force_sweep) {
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// Notify sweeper that we want to force a sweep and wait for completion.
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// In case a sweep currently takes place we timeout and try again because
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// we want to enforce a full sweep.
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CodeCache_lock->notify();
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CodeCache_lock->wait(Mutex::_no_safepoint_check_flag, 1000);
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}
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}
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/**
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* Handle a safepoint request
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*/
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void NMethodSweeper::handle_safepoint_request() {
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if (SafepointSynchronize::is_synchronizing()) {
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if (PrintMethodFlushing && Verbose) {
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tty->print_cr("### Sweep at %d out of %d, yielding to safepoint", _seen, CodeCache::nmethod_count());
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}
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MutexUnlockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
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JavaThread* thread = JavaThread::current();
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ThreadBlockInVM tbivm(thread);
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thread->java_suspend_self();
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}
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}
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/**
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* This function invokes the sweeper if at least one of the three conditions is met:
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* (1) The code cache is getting full
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* (2) There are sufficient state changes in/since the last sweep.
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* (3) We have not been sweeping for 'some time'
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*/
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void NMethodSweeper::possibly_sweep() {
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assert(JavaThread::current()->thread_state() == _thread_in_vm, "must run in vm mode");
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// If there was no state change while nmethod sweeping, 'should_sweep' will be false.
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// This is one of the two places where should_sweep can be set to true. The general
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// idea is as follows: If there is enough free space in the code cache, there is no
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// need to invoke the sweeper. The following formula (which determines whether to invoke
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// the sweeper or not) depends on the assumption that for larger ReservedCodeCacheSizes
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// we need less frequent sweeps than for smaller ReservedCodecCacheSizes. Furthermore,
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// the formula considers how much space in the code cache is currently used. Here are
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// some examples that will (hopefully) help in understanding.
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//
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// Small ReservedCodeCacheSizes: (e.g., < 16M) We invoke the sweeper every time, since
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// the result of the division is 0. This
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// keeps the used code cache size small
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// (important for embedded Java)
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// Large ReservedCodeCacheSize : (e.g., 256M + code cache is 10% full). The formula
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// computes: (256 / 16) - 1 = 15
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// As a result, we invoke the sweeper after
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// 15 invocations of 'mark_active_nmethods.
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// Large ReservedCodeCacheSize: (e.g., 256M + code Cache is 90% full). The formula
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// computes: (256 / 16) - 10 = 6.
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if (!_should_sweep) {
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const int time_since_last_sweep = _time_counter - _last_sweep;
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// ReservedCodeCacheSize has an 'unsigned' type. We need a 'signed' type for max_wait_time,
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// since 'time_since_last_sweep' can be larger than 'max_wait_time'. If that happens using
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// an unsigned type would cause an underflow (wait_until_next_sweep becomes a large positive
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// value) that disables the intended periodic sweeps.
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const int max_wait_time = ReservedCodeCacheSize / (16 * M);
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double wait_until_next_sweep = max_wait_time - time_since_last_sweep -
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MAX2(CodeCache::reverse_free_ratio(CodeBlobType::MethodProfiled),
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CodeCache::reverse_free_ratio(CodeBlobType::MethodNonProfiled));
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assert(wait_until_next_sweep <= (double)max_wait_time, "Calculation of code cache sweeper interval is incorrect");
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if ((wait_until_next_sweep <= 0.0) || !CompileBroker::should_compile_new_jobs()) {
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_should_sweep = true;
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}
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}
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// Remember if this was a forced sweep
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bool forced = _force_sweep;
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// Force stack scanning if there is only 10% free space in the code cache.
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// We force stack scanning only if the non-profiled code heap gets full, since critical
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// allocations go to the non-profiled heap and we must be make sure that there is
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// enough space.
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double free_percent = 1 / CodeCache::reverse_free_ratio(CodeBlobType::MethodNonProfiled) * 100;
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if (free_percent <= StartAggressiveSweepingAt) {
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do_stack_scanning();
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}
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if (_should_sweep || forced) {
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init_sweeper_log();
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sweep_code_cache();
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}
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// We are done with sweeping the code cache once.
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_total_nof_code_cache_sweeps++;
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_last_sweep = _time_counter;
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// Reset flag; temporarily disables sweeper
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_should_sweep = false;
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// If there was enough state change, 'possibly_enable_sweeper()'
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// sets '_should_sweep' to true
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possibly_enable_sweeper();
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// Reset _bytes_changed only if there was enough state change. _bytes_changed
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// can further increase by calls to 'report_state_change'.
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if (_should_sweep) {
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_bytes_changed = 0;
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}
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if (forced) {
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// Notify requester that forced sweep finished
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assert(_force_sweep, "Should be a forced sweep");
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
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_force_sweep = false;
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CodeCache_lock->notify();
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}
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}
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void NMethodSweeper::sweep_code_cache() {
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ResourceMark rm;
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Ticks sweep_start_counter = Ticks::now();
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int flushed_count = 0;
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int zombified_count = 0;
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int flushed_c2_count = 0;
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if (PrintMethodFlushing && Verbose) {
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tty->print_cr("### Sweep at %d out of %d", _seen, CodeCache::nmethod_count());
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}
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int swept_count = 0;
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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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int freed_memory = 0;
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{
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MutexLockerEx mu(CodeCache_lock, Mutex::_no_safepoint_check_flag);
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while (!_current.end()) {
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swept_count++;
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// Since we will give up the CodeCache_lock, always skip ahead
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// to the next nmethod. Other blobs can be deleted by other
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// threads but nmethods are only reclaimed by the sweeper.
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nmethod* nm = _current.method();
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_current.next();
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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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// Save information before potentially flushing the nmethod
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int size = nm->total_size();
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bool is_c2_method = nm->is_compiled_by_c2();
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bool is_osr = nm->is_osr_method();
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int compile_id = nm->compile_id();
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intptr_t address = p2i(nm);
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const char* state_before = nm->state();
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const char* state_after = "";
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MethodStateChange type = process_nmethod(nm);
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switch (type) {
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case Flushed:
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state_after = "flushed";
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freed_memory += size;
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++flushed_count;
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if (is_c2_method) {
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++flushed_c2_count;
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}
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break;
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case MadeZombie:
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state_after = "made zombie";
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++zombified_count;
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break;
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case None:
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break;
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default:
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ShouldNotReachHere();
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}
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if (PrintMethodFlushing && Verbose && type != None) {
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tty->print_cr("### %s nmethod %3d/" PTR_FORMAT " (%s) %s", is_osr ? "osr" : "", compile_id, address, state_before, state_after);
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}
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}
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_seen++;
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handle_safepoint_request();
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}
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}
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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()) {
|
|
event.set_starttime(sweep_start_counter);
|
|
event.set_endtime(sweep_end_counter);
|
|
event.set_sweepIndex(_traversals);
|
|
event.set_sweptCount(swept_count);
|
|
event.set_flushedCount(flushed_count);
|
|
event.set_zombifiedCount(zombified_count);
|
|
event.commit();
|
|
}
|
|
|
|
#ifdef ASSERT
|
|
if(PrintMethodFlushing) {
|
|
tty->print_cr("### sweeper: sweep time(" JLONG_FORMAT "): ", sweep_time.value());
|
|
}
|
|
#endif
|
|
|
|
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:
|
|
CodeCacheSweeperThread* _thread;
|
|
public:
|
|
NMethodMarker(nmethod* nm) {
|
|
JavaThread* current = JavaThread::current();
|
|
assert (current->is_Code_cache_sweeper_thread(), "Must be");
|
|
_thread = (CodeCacheSweeperThread*)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) {
|
|
// Make sure the released nmethod is no longer referenced by the sweeper thread
|
|
CodeCacheSweeperThread* thread = (CodeCacheSweeperThread*)JavaThread::current();
|
|
thread->set_scanned_nmethod(NULL);
|
|
|
|
// 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();
|
|
}
|
|
|
|
NMethodSweeper::MethodStateChange NMethodSweeper::process_nmethod(nmethod* nm) {
|
|
assert(nm != 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.
|
|
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/unloaded nmethods
|
|
MutexLocker cl(CompiledIC_lock);
|
|
nm->cleanup_inline_caches();
|
|
SWEEP(nm);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
if (nm->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(!nm->is_locked_by_vm(), "must not flush locked nmethods");
|
|
release_nmethod(nm);
|
|
assert(result == None, "sanity");
|
|
result = Flushed;
|
|
} 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()) {
|
|
// Clear ICStubs to prevent back patching stubs of zombie or flushed
|
|
// 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();
|
|
SWEEP(nm);
|
|
// 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 (nm->is_osr_method() && !nm->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(nm->is_zombie(), "nmethod must be unregistered");
|
|
release_nmethod(nm);
|
|
assert(result == None, "sanity");
|
|
result = Flushed;
|
|
} else {
|
|
assert(result == None, "sanity");
|
|
result = MadeZombie;
|
|
assert(nm->is_zombie(), "nmethod must be zombie");
|
|
}
|
|
} else {
|
|
// Still alive, clean up its inline caches
|
|
MutexLocker cl(CompiledIC_lock);
|
|
nm->cleanup_inline_caches();
|
|
SWEEP(nm);
|
|
}
|
|
} else if (nm->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.
|
|
{
|
|
// 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();
|
|
}
|
|
if (nm->is_osr_method()) {
|
|
SWEEP(nm);
|
|
// No inline caches will ever point to osr methods, so we can just remove it
|
|
release_nmethod(nm);
|
|
assert(result == None, "sanity");
|
|
result = Flushed;
|
|
} else {
|
|
// Code cache state change is tracked in make_zombie()
|
|
nm->make_zombie();
|
|
SWEEP(nm);
|
|
assert(result == None, "sanity");
|
|
result = MadeZombie;
|
|
}
|
|
} else {
|
|
possibly_flush(nm);
|
|
// Clean inline caches that point to zombie/non-entrant/unloaded nmethods
|
|
MutexLocker cl(CompiledIC_lock);
|
|
nm->cleanup_inline_caches();
|
|
SWEEP(nm);
|
|
}
|
|
return result;
|
|
}
|
|
|
|
|
|
void NMethodSweeper::possibly_flush(nmethod* nm) {
|
|
if (UseCodeCacheFlushing) {
|
|
if (!nm->is_locked_by_vm() && !nm->is_native_method()) {
|
|
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() {
|
|
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);
|
|
}
|