duke@435: /* sla@5237: * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. duke@435: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@435: * duke@435: * This code is free software; you can redistribute it and/or modify it duke@435: * under the terms of the GNU General Public License version 2 only, as duke@435: * published by the Free Software Foundation. duke@435: * duke@435: * This code is distributed in the hope that it will be useful, but WITHOUT duke@435: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@435: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@435: * version 2 for more details (a copy is included in the LICENSE file that duke@435: * accompanied this code). duke@435: * duke@435: * You should have received a copy of the GNU General Public License version duke@435: * 2 along with this work; if not, write to the Free Software Foundation, duke@435: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@435: * trims@1907: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA trims@1907: * or visit www.oracle.com if you need additional information or have any trims@1907: * questions. duke@435: * duke@435: */ duke@435: stefank@2314: #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP stefank@2314: #define SHARE_VM_RUNTIME_SWEEPER_HPP stefank@2314: duke@435: // An NmethodSweeper is an incremental cleaner for: duke@435: // - cleanup inline caches anoll@5792: // - reclamation of nmethods anoll@5792: // Removing nmethods from the code cache includes two operations anoll@5792: // 1) mark active nmethods anoll@5792: // Is done in 'mark_active_nmethods()'. This function is called at a anoll@5792: // safepoint and marks all nmethods that are active on a thread's stack. anoll@5792: // 2) sweep nmethods anoll@5792: // Is done in sweep_code_cache(). This function is the only place in the anoll@5792: // sweeper where memory is reclaimed. Note that sweep_code_cache() is not anoll@5792: // called at a safepoint. However, sweep_code_cache() stops executing if anoll@5792: // another thread requests a safepoint. Consequently, 'mark_active_nmethods()' anoll@5792: // and sweep_code_cache() cannot execute at the same time. anoll@5792: // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can anoll@5792: // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency anoll@5792: // invalidation, and (iv) being replaced be a different method version (tiered anoll@5792: // compilation). Not-entrant nmethod cannot be called by Java threads, but they anoll@5792: // can still be active on the stack. To ensure that active nmethod are not reclaimed, anoll@5792: // we have to wait until the next marking phase has completed. If a not-entrant anoll@5792: // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely anoll@5792: // remove the nmethod, all inline caches (IC) that point to the the nmethod must be anoll@5792: // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's anoll@5792: // state change happens during separate sweeps. It may take at least 3 sweeps before an anoll@5792: // nmethod's space is freed. Sweeping is currently done by compiler threads between anoll@5792: // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache anoll@5792: // is full. duke@435: duke@435: class NMethodSweeper : public AllStatic { sla@5237: static long _traversals; // Stack scan count, also sweep ID. sla@5237: static nmethod* _current; // Current nmethod sla@5237: static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache sla@5237: static int _flushed_count; // Nof. nmethods flushed in current sweep sla@5237: static int _zombified_count; // Nof. nmethods made zombie in current sweep sla@5237: static int _marked_count; // Nof. nmethods marked for reclaim in current sweep never@1999: neliasso@5038: static volatile int _invocations; // No. of invocations left until we are completed with this pass neliasso@5038: static volatile int _sweep_started; // Flag to control conc sweeper duke@435: anoll@5792: //The following are reset in mark_active_nmethods and synchronized by the safepoint anoll@5792: static bool _request_mark_phase; // Indicates that a change has happend and we need another mark pahse, anoll@5792: // always checked and reset at a safepoint so memory will be in sync. anoll@5792: static int _locked_seen; // Number of locked nmethods encountered during the scan duke@435: static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack duke@435: sla@5237: // Stat counters sla@5237: static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed sla@5237: static jlong _total_time_sweeping; // Accumulated time sweeping sla@5237: static jlong _total_time_this_sweep; // Total time this sweep sla@5237: static jlong _peak_sweep_time; // Peak time for a full sweep sla@5237: static jlong _peak_sweep_fraction_time; // Peak time sweeping one fraction sla@5237: anoll@5792: static int process_nmethod(nmethod *nm); coleenp@4037: static void release_nmethod(nmethod* nm); coleenp@4037: neliasso@5038: static bool sweep_in_progress(); anoll@5792: static void sweep_code_cache(); anoll@5792: static void request_nmethod_marking() { _request_mark_phase = true; } anoll@5792: static void reset_nmethod_marking() { _request_mark_phase = false; } anoll@5792: static bool need_marking_phase() { return _request_mark_phase; } anoll@5792: anoll@5792: static int _hotness_counter_reset_val; never@1999: duke@435: public: sla@5237: static long traversal_count() { return _traversals; } sla@5237: static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } sla@5237: static jlong total_time_sweeping() { return _total_time_sweeping; } sla@5237: static jlong peak_sweep_time() { return _peak_sweep_time; } sla@5237: static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } anoll@5792: static void log_sweep(const char* msg, const char* format = NULL, ...); anoll@5792: duke@435: never@2916: #ifdef ASSERT johnc@5548: static bool is_sweeping(nmethod* which) { return _current == which; } never@2916: // Keep track of sweeper activity in the ring buffer never@2916: static void record_sweep(nmethod* nm, int line); never@2916: static void report_events(int id, address entry); never@2916: static void report_events(); never@2916: #endif never@2916: anoll@5792: static void mark_active_nmethods(); // Invoked at the end of each safepoint anoll@5792: static void possibly_sweep(); // Compiler threads call this to sweep duke@435: anoll@5792: static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2); anoll@5792: static int hotness_counter_reset_val(); anoll@5792: anoll@5792: static void notify() { neliasso@5038: // Request a new sweep of the code cache from the beginning. No duke@435: // need to synchronize the setting of this flag since it only duke@435: // changes to false at safepoint so we can never overwrite it with false. anoll@5792: request_nmethod_marking(); duke@435: } duke@435: }; stefank@2314: stefank@2314: #endif // SHARE_VM_RUNTIME_SWEEPER_HPP