Tue, 24 Dec 2013 11:48:39 -0800
8029233: Update copyright year to match last edit in jdk8 hotspot repository for 2013
Summary: Copyright year updated for files modified during 2013
Reviewed-by: twisti, iveresov
1 /*
2 * Copyright (c) 1997, 2013, 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 */
25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP
26 #define SHARE_VM_RUNTIME_SWEEPER_HPP
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.
56 class NMethodSweeper : public AllStatic {
57 static long _traversals; // Stack scan count, also sweep ID.
58 static long _time_counter; // Virtual time used to periodically invoke sweeper
59 static long _last_sweep; // Value of _time_counter when the last sweep happened
60 static nmethod* _current; // Current nmethod
61 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache
62 static int _flushed_count; // Nof. nmethods flushed in current sweep
63 static int _zombified_count; // Nof. nmethods made zombie in current sweep
64 static int _marked_for_reclamation_count; // Nof. nmethods marked for reclaim in current sweep
66 static volatile int _sweep_fractions_left; // Nof. invocations left until we are completed with this pass
67 static volatile int _sweep_started; // Flag to control conc sweeper
68 static volatile bool _should_sweep; // Indicates if we should invoke the sweeper
69 static volatile int _bytes_changed; // Counts the total nmethod size if the nmethod changed from:
70 // 1) alive -> not_entrant
71 // 2) not_entrant -> zombie
72 // 3) zombie -> marked_for_reclamation
73 // Stat counters
74 static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed
75 static Tickspan _total_time_sweeping; // Accumulated time sweeping
76 static Tickspan _total_time_this_sweep; // Total time this sweep
77 static Tickspan _peak_sweep_time; // Peak time for a full sweep
78 static Tickspan _peak_sweep_fraction_time; // Peak time sweeping one fraction
80 static int process_nmethod(nmethod *nm);
81 static void release_nmethod(nmethod* nm);
83 static bool sweep_in_progress();
84 static void sweep_code_cache();
86 static int _hotness_counter_reset_val;
88 public:
89 static long traversal_count() { return _traversals; }
90 static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; }
91 static const Tickspan total_time_sweeping() { return _total_time_sweeping; }
92 static const Tickspan peak_sweep_time() { return _peak_sweep_time; }
93 static const Tickspan peak_sweep_fraction_time() { return _peak_sweep_fraction_time; }
94 static void log_sweep(const char* msg, const char* format = NULL, ...);
97 #ifdef ASSERT
98 static bool is_sweeping(nmethod* which) { return _current == which; }
99 // Keep track of sweeper activity in the ring buffer
100 static void record_sweep(nmethod* nm, int line);
101 static void report_events(int id, address entry);
102 static void report_events();
103 #endif
105 static void mark_active_nmethods(); // Invoked at the end of each safepoint
106 static void possibly_sweep(); // Compiler threads call this to sweep
108 static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2);
109 static int hotness_counter_reset_val();
110 static void report_state_change(nmethod* nm);
111 static void possibly_enable_sweeper();
112 };
114 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP