f41f86bff1
Changed implementation of forceNMethodSweep() to request sweep from existing sweeper thread. Reviewed-by: kvn, mgerdin, dholmes
130 lines
6.4 KiB
C++
130 lines
6.4 KiB
C++
/*
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* Copyright (c) 1997, 2014, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef SHARE_VM_RUNTIME_SWEEPER_HPP
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#define SHARE_VM_RUNTIME_SWEEPER_HPP
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class WhiteBox;
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#include "utilities/ticks.hpp"
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// An NmethodSweeper is an incremental cleaner for:
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// - cleanup inline caches
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// - reclamation of nmethods
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// Removing nmethods from the code cache includes two operations
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// 1) mark active nmethods
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// Is done in 'mark_active_nmethods()'. This function is called at a
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// safepoint and marks all nmethods that are active on a thread's stack.
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// 2) sweep nmethods
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// Is done in sweep_code_cache(). This function is the only place in the
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// sweeper where memory is reclaimed. Note that sweep_code_cache() is not
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// called at a safepoint. However, sweep_code_cache() stops executing if
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// another thread requests a safepoint. Consequently, 'mark_active_nmethods()'
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// and sweep_code_cache() cannot execute at the same time.
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// To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can
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// be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency
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// invalidation, and (iv) being replaced be a different method version (tiered
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// compilation). Not-entrant nmethod cannot be called by Java threads, but they
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// can still be active on the stack. To ensure that active nmethod are not reclaimed,
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// we have to wait until the next marking phase has completed. If a not-entrant
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// nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely
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// remove the nmethod, all inline caches (IC) that point to the the nmethod must be
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// cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's
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// state change happens during separate sweeps. It may take at least 3 sweeps before an
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// nmethod's space is freed.
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class NMethodSweeper : public AllStatic {
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private:
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enum MethodStateChange {
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None,
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MadeZombie,
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MarkedForReclamation,
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Flushed
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};
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static long _traversals; // Stack scan count, also sweep ID.
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static long _total_nof_code_cache_sweeps; // Total number of full sweeps of the code cache
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static long _time_counter; // Virtual time used to periodically invoke sweeper
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static long _last_sweep; // Value of _time_counter when the last sweep happened
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static NMethodIterator _current; // Current nmethod
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static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache
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static volatile int _sweep_started; // Flag to control conc sweeper
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static volatile bool _should_sweep; // Indicates if we should invoke the sweeper
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static volatile bool _force_sweep; // Indicates if we should force a sweep
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static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from:
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// 1) alive -> not_entrant
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// 2) not_entrant -> zombie
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// 3) zombie -> marked_for_reclamation
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// Stat counters
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static long _total_nof_methods_reclaimed; // Accumulated nof methods flushed
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static long _total_nof_c2_methods_reclaimed; // Accumulated nof C2-compiled methods flushed
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static size_t _total_flushed_size; // Total size of flushed methods
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static int _hotness_counter_reset_val;
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static Tickspan _total_time_sweeping; // Accumulated time sweeping
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static Tickspan _total_time_this_sweep; // Total time this sweep
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static Tickspan _peak_sweep_time; // Peak time for a full sweep
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static Tickspan _peak_sweep_fraction_time; // Peak time sweeping one fraction
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static Monitor* _stat_lock;
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static MethodStateChange process_nmethod(nmethod *nm);
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static void release_nmethod(nmethod* nm);
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static void init_sweeper_log() NOT_DEBUG_RETURN;
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static bool wait_for_stack_scanning();
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static void sweep_code_cache();
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static void handle_safepoint_request();
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static void do_stack_scanning();
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static void possibly_sweep();
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public:
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static long traversal_count() { return _traversals; }
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static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; }
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static const Tickspan total_time_sweeping() { return _total_time_sweeping; }
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static const Tickspan peak_sweep_time() { return _peak_sweep_time; }
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static const Tickspan peak_sweep_fraction_time() { return _peak_sweep_fraction_time; }
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static void log_sweep(const char* msg, const char* format = NULL, ...) ATTRIBUTE_PRINTF(2, 3);
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#ifdef ASSERT
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static bool is_sweeping(nmethod* which) { return _current.method() == which; }
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// Keep track of sweeper activity in the ring buffer
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static void record_sweep(nmethod* nm, int line);
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static void report_events(int id, address entry);
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static void report_events();
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#endif
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static void mark_active_nmethods(); // Invoked at the end of each safepoint
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static void sweeper_loop();
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static void notify(int code_blob_type); // Possibly start the sweeper thread.
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static void force_sweep();
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static int hotness_counter_reset_val();
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static void report_state_change(nmethod* nm);
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static void possibly_enable_sweeper();
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static void possibly_flush(nmethod* nm);
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static void print(); // Printing/debugging
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};
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#endif // SHARE_VM_RUNTIME_SWEEPER_HPP
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