annotate src/share/vm/runtime/sweeper.hpp @ 5772:6aa49042b101

8025277: Add -XX: flag to print code cache sweeper statistics Summary: New diagnostic flag prints statistics about the code cache sweeper Reviewed-by: kvn Contributed-by: tobi.hartmann@gmail.com
author anoll
date Thu, 19 Dec 2013 14:08:02 +0100
parents 86e6d691f2e1
children 78bbf4d43a14
rev   line source
duke@0 1 /*
sla@4802 2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
duke@0 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@0 4 *
duke@0 5 * This code is free software; you can redistribute it and/or modify it
duke@0 6 * under the terms of the GNU General Public License version 2 only, as
duke@0 7 * published by the Free Software Foundation.
duke@0 8 *
duke@0 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@0 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@0 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@0 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@0 13 * accompanied this code).
duke@0 14 *
duke@0 15 * You should have received a copy of the GNU General Public License version
duke@0 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@0 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@0 18 *
trims@1472 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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duke@0 23 */
duke@0 24
stefank@1879 25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP
stefank@1879 26 #define SHARE_VM_RUNTIME_SWEEPER_HPP
stefank@1879 27
mgronlun@5696 28 #include "utilities/ticks.hpp"
duke@0 29 // An NmethodSweeper is an incremental cleaner for:
duke@0 30 // - cleanup inline caches
anoll@5357 31 // - reclamation of nmethods
anoll@5357 32 // Removing nmethods from the code cache includes two operations
anoll@5357 33 // 1) mark active nmethods
anoll@5357 34 // Is done in 'mark_active_nmethods()'. This function is called at a
anoll@5357 35 // safepoint and marks all nmethods that are active on a thread's stack.
anoll@5357 36 // 2) sweep nmethods
anoll@5357 37 // Is done in sweep_code_cache(). This function is the only place in the
anoll@5357 38 // sweeper where memory is reclaimed. Note that sweep_code_cache() is not
anoll@5357 39 // called at a safepoint. However, sweep_code_cache() stops executing if
anoll@5357 40 // another thread requests a safepoint. Consequently, 'mark_active_nmethods()'
anoll@5357 41 // and sweep_code_cache() cannot execute at the same time.
anoll@5357 42 // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can
anoll@5357 43 // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency
anoll@5357 44 // invalidation, and (iv) being replaced be a different method version (tiered
anoll@5357 45 // compilation). Not-entrant nmethod cannot be called by Java threads, but they
anoll@5357 46 // can still be active on the stack. To ensure that active nmethod are not reclaimed,
anoll@5357 47 // we have to wait until the next marking phase has completed. If a not-entrant
anoll@5357 48 // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely
anoll@5357 49 // remove the nmethod, all inline caches (IC) that point to the the nmethod must be
anoll@5357 50 // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's
anoll@5357 51 // state change happens during separate sweeps. It may take at least 3 sweeps before an
anoll@5357 52 // nmethod's space is freed. Sweeping is currently done by compiler threads between
anoll@5357 53 // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache
anoll@5357 54 // is full.
duke@0 55
duke@0 56 class NMethodSweeper : public AllStatic {
anoll@5772 57 static long _traversals; // Stack scan count, also sweep ID.
anoll@5772 58 static long _total_nof_code_cache_sweeps; // Total number of full sweeps of the code cache
anoll@5772 59 static long _time_counter; // Virtual time used to periodically invoke sweeper
anoll@5772 60 static long _last_sweep; // Value of _time_counter when the last sweep happened
anoll@5772 61 static nmethod* _current; // Current nmethod
anoll@5772 62 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache
anoll@5772 63 static int _flushed_count; // Nof. nmethods flushed in current sweep
anoll@5772 64 static int _zombified_count; // Nof. nmethods made zombie in current sweep
anoll@5772 65 static int _marked_for_reclamation_count; // Nof. nmethods marked for reclaim in current sweep
never@1564 66
anoll@5772 67 static volatile int _sweep_fractions_left; // Nof. invocations left until we are completed with this pass
anoll@5772 68 static volatile int _sweep_started; // Flag to control conc sweeper
anoll@5772 69 static volatile bool _should_sweep; // Indicates if we should invoke the sweeper
anoll@5772 70 static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from:
anoll@5772 71 // 1) alive -> not_entrant
anoll@5772 72 // 2) not_entrant -> zombie
anoll@5772 73 // 3) zombie -> marked_for_reclamation
sla@4802 74 // Stat counters
anoll@5772 75 static long _total_nof_methods_reclaimed; // Accumulated nof methods flushed
anoll@5772 76 static long _total_nof_c2_methods_reclaimed; // Accumulated nof C2-compiled methods flushed
anoll@5772 77 static size_t _total_flushed_size; // Total size of flushed methods
anoll@5772 78 static int _hotness_counter_reset_val;
anoll@5772 79
anoll@5772 80 static Tickspan _total_time_sweeping; // Accumulated time sweeping
anoll@5772 81 static Tickspan _total_time_this_sweep; // Total time this sweep
anoll@5772 82 static Tickspan _peak_sweep_time; // Peak time for a full sweep
anoll@5772 83 static Tickspan _peak_sweep_fraction_time; // Peak time sweeping one fraction
sla@4802 84
anoll@5357 85 static int process_nmethod(nmethod *nm);
coleenp@3602 86 static void release_nmethod(nmethod* nm);
coleenp@3602 87
neliasso@4603 88 static bool sweep_in_progress();
anoll@5357 89 static void sweep_code_cache();
anoll@5357 90
duke@0 91 public:
sla@4802 92 static long traversal_count() { return _traversals; }
sla@4802 93 static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; }
mgronlun@5696 94 static const Tickspan total_time_sweeping() { return _total_time_sweeping; }
mgronlun@5696 95 static const Tickspan peak_sweep_time() { return _peak_sweep_time; }
mgronlun@5696 96 static const Tickspan peak_sweep_fraction_time() { return _peak_sweep_fraction_time; }
anoll@5357 97 static void log_sweep(const char* msg, const char* format = NULL, ...);
anoll@5357 98
duke@0 99
never@2481 100 #ifdef ASSERT
johnc@5113 101 static bool is_sweeping(nmethod* which) { return _current == which; }
never@2481 102 // Keep track of sweeper activity in the ring buffer
never@2481 103 static void record_sweep(nmethod* nm, int line);
never@2481 104 static void report_events(int id, address entry);
never@2481 105 static void report_events();
never@2481 106 #endif
never@2481 107
anoll@5357 108 static void mark_active_nmethods(); // Invoked at the end of each safepoint
anoll@5357 109 static void possibly_sweep(); // Compiler threads call this to sweep
duke@0 110
anoll@5357 111 static int hotness_counter_reset_val();
anoll@5664 112 static void report_state_change(nmethod* nm);
anoll@5664 113 static void possibly_enable_sweeper();
anoll@5772 114 static void print(); // Printing/debugging
duke@0 115 };
stefank@1879 116
stefank@1879 117 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP