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comparison: src/share/vm/runtime/sweeper.hpp
src/share/vm/runtime/sweeper.hpp
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| 1 /* | |
| 2 * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved. | |
| 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | |
| 4 * | |
| 5 * This code is free software; you can redistribute it and/or modify it | |
| 6 * under the terms of the GNU General Public License version 2 only, as | |
| 7 * published by the Free Software Foundation. | |
| 8 * | |
| 9 * This code is distributed in the hope that it will be useful, but WITHOUT | |
| 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 12 * version 2 for more details (a copy is included in the LICENSE file that | |
| 13 * accompanied this code). | |
| 14 * | |
| 15 * You should have received a copy of the GNU General Public License version | |
| 16 * 2 along with this work; if not, write to the Free Software Foundation, | |
| 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | |
| 18 * | |
| 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 20 * or visit www.oracle.com if you need additional information or have any | |
| 21 * questions. | |
| 22 * | |
| 23 */ | |
| 24 | |
| 25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP | |
| 26 #define SHARE_VM_RUNTIME_SWEEPER_HPP | |
| 27 | |
| 28 #include "utilities/ticks.hpp" | |
| 29 // An NmethodSweeper is an incremental cleaner for: | |
| 30 // - cleanup inline caches | |
| 31 // - reclamation of nmethods | |
| 32 // Removing nmethods from the code cache includes two operations | |
| 33 // 1) mark active nmethods | |
| 34 // Is done in 'mark_active_nmethods()'. This function is called at a | |
| 35 // safepoint and marks all nmethods that are active on a thread's stack. | |
| 36 // 2) sweep nmethods | |
| 37 // Is done in sweep_code_cache(). This function is the only place in the | |
| 38 // sweeper where memory is reclaimed. Note that sweep_code_cache() is not | |
| 39 // called at a safepoint. However, sweep_code_cache() stops executing if | |
| 40 // another thread requests a safepoint. Consequently, 'mark_active_nmethods()' | |
| 41 // and sweep_code_cache() cannot execute at the same time. | |
| 42 // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can | |
| 43 // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency | |
| 44 // invalidation, and (iv) being replaced be a different method version (tiered | |
| 45 // compilation). Not-entrant nmethod cannot be called by Java threads, but they | |
| 46 // can still be active on the stack. To ensure that active nmethod are not reclaimed, | |
| 47 // we have to wait until the next marking phase has completed. If a not-entrant | |
| 48 // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely | |
| 49 // remove the nmethod, all inline caches (IC) that point to the the nmethod must be | |
| 50 // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's | |
| 51 // state change happens during separate sweeps. It may take at least 3 sweeps before an | |
| 52 // nmethod's space is freed. Sweeping is currently done by compiler threads between | |
| 53 // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache | |
| 54 // is full. | |
| 55 | |
| 56 class NMethodSweeper : public AllStatic { | |
| 57 static long _traversals; // Stack scan count, also sweep ID. | |
| 58 static long _total_nof_code_cache_sweeps; // Total number of full sweeps of the code cache | |
| 59 static long _time_counter; // Virtual time used to periodically invoke sweeper | |
| 60 static long _last_sweep; // Value of _time_counter when the last sweep happened | |
| 61 static nmethod* _current; // Current nmethod | |
| 62 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache | |
| 63 static int _flushed_count; // Nof. nmethods flushed in current sweep | |
| 64 static int _zombified_count; // Nof. nmethods made zombie in current sweep | |
| 65 static int _marked_for_reclamation_count; // Nof. nmethods marked for reclaim in current sweep | |
| 66 | |
| 67 static volatile int _sweep_fractions_left; // Nof. invocations left until we are completed with this pass | |
| 68 static volatile int _sweep_started; // Flag to control conc sweeper | |
| 69 static volatile bool _should_sweep; // Indicates if we should invoke the sweeper | |
| 70 static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from: | |
| 71 // 1) alive -> not_entrant | |
| 72 // 2) not_entrant -> zombie | |
| 73 // 3) zombie -> marked_for_reclamation | |
| 74 // Stat counters | |
| 75 static long _total_nof_methods_reclaimed; // Accumulated nof methods flushed | |
| 76 static long _total_nof_c2_methods_reclaimed; // Accumulated nof C2-compiled methods flushed | |
| 77 static size_t _total_flushed_size; // Total size of flushed methods | |
| 78 static int _hotness_counter_reset_val; | |
| 79 | |
| 80 static Tickspan _total_time_sweeping; // Accumulated time sweeping | |
| 81 static Tickspan _total_time_this_sweep; // Total time this sweep | |
| 82 static Tickspan _peak_sweep_time; // Peak time for a full sweep | |
| 83 static Tickspan _peak_sweep_fraction_time; // Peak time sweeping one fraction | |
| 84 | |
| 85 static int process_nmethod(nmethod *nm); | |
| 86 static void release_nmethod(nmethod* nm); | |
| 87 | |
| 88 static bool sweep_in_progress(); | |
| 89 static void sweep_code_cache(); | |
| 90 | |
| 91 public: | |
| 92 static long traversal_count() { return _traversals; } | |
| 93 static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } | |
| 94 static const Tickspan total_time_sweeping() { return _total_time_sweeping; } | |
| 95 static const Tickspan peak_sweep_time() { return _peak_sweep_time; } | |
| 96 static const Tickspan peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } | |
| 97 static void log_sweep(const char* msg, const char* format = NULL, ...) ATTRIBUTE_PRINTF(2, 3); | |
| 98 | |
| 99 | |
| 100 #ifdef ASSERT | |
| 101 static bool is_sweeping(nmethod* which) { return _current == which; } | |
| 102 // Keep track of sweeper activity in the ring buffer | |
| 103 static void record_sweep(nmethod* nm, int line); | |
| 104 static void report_events(int id, address entry); | |
| 105 static void report_events(); | |
| 106 #endif | |
| 107 | |
| 108 static void mark_active_nmethods(); // Invoked at the end of each safepoint | |
| 109 static void possibly_sweep(); // Compiler threads call this to sweep | |
| 110 | |
| 111 static int hotness_counter_reset_val(); | |
| 112 static void report_state_change(nmethod* nm); | |
| 113 static void possibly_enable_sweeper(); | |
| 114 static void print(); // Printing/debugging | |
| 115 }; | |
| 116 | |
| 117 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP |
