1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/runtime/sweeper.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,117 @@
1.4 +/*
1.5 + * Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_RUNTIME_SWEEPER_HPP
1.29 +#define SHARE_VM_RUNTIME_SWEEPER_HPP
1.30 +
1.31 +#include "utilities/ticks.hpp"
1.32 +// An NmethodSweeper is an incremental cleaner for:
1.33 +// - cleanup inline caches
1.34 +// - reclamation of nmethods
1.35 +// Removing nmethods from the code cache includes two operations
1.36 +// 1) mark active nmethods
1.37 +// Is done in 'mark_active_nmethods()'. This function is called at a
1.38 +// safepoint and marks all nmethods that are active on a thread's stack.
1.39 +// 2) sweep nmethods
1.40 +// Is done in sweep_code_cache(). This function is the only place in the
1.41 +// sweeper where memory is reclaimed. Note that sweep_code_cache() is not
1.42 +// called at a safepoint. However, sweep_code_cache() stops executing if
1.43 +// another thread requests a safepoint. Consequently, 'mark_active_nmethods()'
1.44 +// and sweep_code_cache() cannot execute at the same time.
1.45 +// To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can
1.46 +// be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency
1.47 +// invalidation, and (iv) being replaced be a different method version (tiered
1.48 +// compilation). Not-entrant nmethod cannot be called by Java threads, but they
1.49 +// can still be active on the stack. To ensure that active nmethod are not reclaimed,
1.50 +// we have to wait until the next marking phase has completed. If a not-entrant
1.51 +// nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely
1.52 +// remove the nmethod, all inline caches (IC) that point to the the nmethod must be
1.53 +// cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's
1.54 +// state change happens during separate sweeps. It may take at least 3 sweeps before an
1.55 +// nmethod's space is freed. Sweeping is currently done by compiler threads between
1.56 +// compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache
1.57 +// is full.
1.58 +
1.59 +class NMethodSweeper : public AllStatic {
1.60 + static long _traversals; // Stack scan count, also sweep ID.
1.61 + static long _total_nof_code_cache_sweeps; // Total number of full sweeps of the code cache
1.62 + static long _time_counter; // Virtual time used to periodically invoke sweeper
1.63 + static long _last_sweep; // Value of _time_counter when the last sweep happened
1.64 + static nmethod* _current; // Current nmethod
1.65 + static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache
1.66 + static int _flushed_count; // Nof. nmethods flushed in current sweep
1.67 + static int _zombified_count; // Nof. nmethods made zombie in current sweep
1.68 + static int _marked_for_reclamation_count; // Nof. nmethods marked for reclaim in current sweep
1.69 +
1.70 + static volatile int _sweep_fractions_left; // Nof. invocations left until we are completed with this pass
1.71 + static volatile int _sweep_started; // Flag to control conc sweeper
1.72 + static volatile bool _should_sweep; // Indicates if we should invoke the sweeper
1.73 + static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from:
1.74 + // 1) alive -> not_entrant
1.75 + // 2) not_entrant -> zombie
1.76 + // 3) zombie -> marked_for_reclamation
1.77 + // Stat counters
1.78 + static long _total_nof_methods_reclaimed; // Accumulated nof methods flushed
1.79 + static long _total_nof_c2_methods_reclaimed; // Accumulated nof C2-compiled methods flushed
1.80 + static size_t _total_flushed_size; // Total size of flushed methods
1.81 + static int _hotness_counter_reset_val;
1.82 +
1.83 + static Tickspan _total_time_sweeping; // Accumulated time sweeping
1.84 + static Tickspan _total_time_this_sweep; // Total time this sweep
1.85 + static Tickspan _peak_sweep_time; // Peak time for a full sweep
1.86 + static Tickspan _peak_sweep_fraction_time; // Peak time sweeping one fraction
1.87 +
1.88 + static int process_nmethod(nmethod *nm);
1.89 + static void release_nmethod(nmethod* nm);
1.90 +
1.91 + static bool sweep_in_progress();
1.92 + static void sweep_code_cache();
1.93 +
1.94 + public:
1.95 + static long traversal_count() { return _traversals; }
1.96 + static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; }
1.97 + static const Tickspan total_time_sweeping() { return _total_time_sweeping; }
1.98 + static const Tickspan peak_sweep_time() { return _peak_sweep_time; }
1.99 + static const Tickspan peak_sweep_fraction_time() { return _peak_sweep_fraction_time; }
1.100 + static void log_sweep(const char* msg, const char* format = NULL, ...) ATTRIBUTE_PRINTF(2, 3);
1.101 +
1.102 +
1.103 +#ifdef ASSERT
1.104 + static bool is_sweeping(nmethod* which) { return _current == which; }
1.105 + // Keep track of sweeper activity in the ring buffer
1.106 + static void record_sweep(nmethod* nm, int line);
1.107 + static void report_events(int id, address entry);
1.108 + static void report_events();
1.109 +#endif
1.110 +
1.111 + static void mark_active_nmethods(); // Invoked at the end of each safepoint
1.112 + static void possibly_sweep(); // Compiler threads call this to sweep
1.113 +
1.114 + static int hotness_counter_reset_val();
1.115 + static void report_state_change(nmethod* nm);
1.116 + static void possibly_enable_sweeper();
1.117 + static void print(); // Printing/debugging
1.118 +};
1.119 +
1.120 +#endif // SHARE_VM_RUNTIME_SWEEPER_HPP
