| /* |
| * 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. |
| * |
| */ |
| |
| #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP |
| #define SHARE_VM_RUNTIME_SWEEPER_HPP |
| |
| #include "utilities/ticks.hpp" |
| // An NmethodSweeper is an incremental cleaner for: |
| // - cleanup inline caches |
| // - reclamation of nmethods |
| // Removing nmethods from the code cache includes two operations |
| // 1) mark active nmethods |
| // Is done in 'mark_active_nmethods()'. This function is called at a |
| // safepoint and marks all nmethods that are active on a thread's stack. |
| // 2) sweep nmethods |
| // Is done in sweep_code_cache(). This function is the only place in the |
| // sweeper where memory is reclaimed. Note that sweep_code_cache() is not |
| // called at a safepoint. However, sweep_code_cache() stops executing if |
| // another thread requests a safepoint. Consequently, 'mark_active_nmethods()' |
| // and sweep_code_cache() cannot execute at the same time. |
| // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can |
| // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency |
| // invalidation, and (iv) being replaced be a different method version (tiered |
| // compilation). Not-entrant nmethod cannot be called by Java threads, but they |
| // can still be active on the stack. To ensure that active nmethod are not reclaimed, |
| // we have to wait until the next marking phase has completed. If a not-entrant |
| // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely |
| // remove the nmethod, all inline caches (IC) that point to the the nmethod must be |
| // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's |
| // state change happens during separate sweeps. It may take at least 3 sweeps before an |
| // nmethod's space is freed. Sweeping is currently done by compiler threads between |
| // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache |
| // is full. |
| |
| class NMethodSweeper : public AllStatic { |
| static long _traversals; // Stack scan count, also sweep ID. |
| static long _total_nof_code_cache_sweeps; // Total number of full sweeps of the code cache |
| static long _time_counter; // Virtual time used to periodically invoke sweeper |
| static long _last_sweep; // Value of _time_counter when the last sweep happened |
| static nmethod* _current; // Current nmethod |
| static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache |
| static int _flushed_count; // Nof. nmethods flushed in current sweep |
| static int _zombified_count; // Nof. nmethods made zombie in current sweep |
| static int _marked_for_reclamation_count; // Nof. nmethods marked for reclaim in current sweep |
| |
| static volatile int _sweep_fractions_left; // Nof. invocations left until we are completed with this pass |
| static volatile int _sweep_started; // Flag to control conc sweeper |
| static volatile bool _should_sweep; // Indicates if we should invoke the sweeper |
| static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from: |
| // 1) alive -> not_entrant |
| // 2) not_entrant -> zombie |
| // 3) zombie -> marked_for_reclamation |
| // Stat counters |
| static long _total_nof_methods_reclaimed; // Accumulated nof methods flushed |
| static long _total_nof_c2_methods_reclaimed; // Accumulated nof C2-compiled methods flushed |
| static size_t _total_flushed_size; // Total size of flushed methods |
| static int _hotness_counter_reset_val; |
| |
| static Tickspan _total_time_sweeping; // Accumulated time sweeping |
| static Tickspan _total_time_this_sweep; // Total time this sweep |
| static Tickspan _peak_sweep_time; // Peak time for a full sweep |
| static Tickspan _peak_sweep_fraction_time; // Peak time sweeping one fraction |
| |
| static int process_nmethod(nmethod *nm); |
| static void release_nmethod(nmethod* nm); |
| |
| static bool sweep_in_progress(); |
| static void sweep_code_cache(); |
| |
| public: |
| static long traversal_count() { return _traversals; } |
| static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } |
| static const Tickspan total_time_sweeping() { return _total_time_sweeping; } |
| static const Tickspan peak_sweep_time() { return _peak_sweep_time; } |
| static const Tickspan peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } |
| static void log_sweep(const char* msg, const char* format = NULL, ...) ATTRIBUTE_PRINTF(2, 3); |
| |
| |
| #ifdef ASSERT |
| static bool is_sweeping(nmethod* which) { return _current == which; } |
| // Keep track of sweeper activity in the ring buffer |
| static void record_sweep(nmethod* nm, int line); |
| static void report_events(int id, address entry); |
| static void report_events(); |
| #endif |
| |
| static void mark_active_nmethods(); // Invoked at the end of each safepoint |
| static void possibly_sweep(); // Compiler threads call this to sweep |
| |
| static int hotness_counter_reset_val(); |
| static void report_state_change(nmethod* nm); |
| static void possibly_enable_sweeper(); |
| static void print(); // Printing/debugging |
| }; |
| |
| #endif // SHARE_VM_RUNTIME_SWEEPER_HPP |
