25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP |
25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP |
26 #define SHARE_VM_RUNTIME_SWEEPER_HPP |
26 #define SHARE_VM_RUNTIME_SWEEPER_HPP |
27 |
27 |
28 // An NmethodSweeper is an incremental cleaner for: |
28 // An NmethodSweeper is an incremental cleaner for: |
29 // - cleanup inline caches |
29 // - cleanup inline caches |
30 // - reclamation of unreferences zombie nmethods |
30 // - reclamation of nmethods |
31 // |
31 // Removing nmethods from the code cache includes two operations |
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32 // 1) mark active nmethods |
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33 // Is done in 'mark_active_nmethods()'. This function is called at a |
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34 // safepoint and marks all nmethods that are active on a thread's stack. |
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35 // 2) sweep nmethods |
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36 // Is done in sweep_code_cache(). This function is the only place in the |
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37 // sweeper where memory is reclaimed. Note that sweep_code_cache() is not |
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38 // called at a safepoint. However, sweep_code_cache() stops executing if |
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39 // another thread requests a safepoint. Consequently, 'mark_active_nmethods()' |
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40 // and sweep_code_cache() cannot execute at the same time. |
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41 // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can |
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42 // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency |
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43 // invalidation, and (iv) being replaced be a different method version (tiered |
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44 // compilation). Not-entrant nmethod cannot be called by Java threads, but they |
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45 // can still be active on the stack. To ensure that active nmethod are not reclaimed, |
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46 // we have to wait until the next marking phase has completed. If a not-entrant |
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47 // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely |
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48 // remove the nmethod, all inline caches (IC) that point to the the nmethod must be |
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49 // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's |
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50 // state change happens during separate sweeps. It may take at least 3 sweeps before an |
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51 // nmethod's space is freed. Sweeping is currently done by compiler threads between |
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52 // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache |
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53 // is full. |
32 |
54 |
33 class NMethodSweeper : public AllStatic { |
55 class NMethodSweeper : public AllStatic { |
34 static long _traversals; // Stack scan count, also sweep ID. |
56 static long _traversals; // Stack scan count, also sweep ID. |
35 static nmethod* _current; // Current nmethod |
57 static nmethod* _current; // Current nmethod |
36 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache |
58 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache |
39 static int _marked_count; // Nof. nmethods marked for reclaim in current sweep |
61 static int _marked_count; // Nof. nmethods marked for reclaim in current sweep |
40 |
62 |
41 static volatile int _invocations; // No. of invocations left until we are completed with this pass |
63 static volatile int _invocations; // No. of invocations left until we are completed with this pass |
42 static volatile int _sweep_started; // Flag to control conc sweeper |
64 static volatile int _sweep_started; // Flag to control conc sweeper |
43 |
65 |
44 //The following are reset in scan_stacks and synchronized by the safepoint |
66 //The following are reset in mark_active_nmethods and synchronized by the safepoint |
45 static bool _resweep; // Indicates that a change has happend and we want another sweep, |
67 static bool _request_mark_phase; // Indicates that a change has happend and we need another mark pahse, |
46 // always checked and reset at a safepoint so memory will be in sync. |
68 // always checked and reset at a safepoint so memory will be in sync. |
47 static int _locked_seen; // Number of locked nmethods encountered during the scan |
69 static int _locked_seen; // Number of locked nmethods encountered during the scan |
48 static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack |
70 static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack |
49 static jint _flush_token; // token that guards method flushing, making sure it is executed only once. |
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50 |
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51 // These are set during a flush, a VM-operation |
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52 static long _last_flush_traversal_id; // trav number at last flush unloading |
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53 static jlong _last_full_flush_time; // timestamp of last emergency unloading |
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54 |
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55 // These are synchronized by the _sweep_started token |
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56 static int _highest_marked; // highest compile id dumped at last emergency unloading |
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57 static int _dead_compile_ids; // number of compile ids that where not in the cache last flush |
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58 |
71 |
59 // Stat counters |
72 // Stat counters |
60 static int _number_of_flushes; // Total of full traversals caused by full cache |
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61 static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed |
73 static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed |
62 static jlong _total_time_sweeping; // Accumulated time sweeping |
74 static jlong _total_time_sweeping; // Accumulated time sweeping |
63 static jlong _total_time_this_sweep; // Total time this sweep |
75 static jlong _total_time_this_sweep; // Total time this sweep |
64 static jlong _peak_sweep_time; // Peak time for a full sweep |
76 static jlong _peak_sweep_time; // Peak time for a full sweep |
65 static jlong _peak_sweep_fraction_time; // Peak time sweeping one fraction |
77 static jlong _peak_sweep_fraction_time; // Peak time sweeping one fraction |
66 static jlong _total_disconnect_time; // Total time cleaning code mem |
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67 static jlong _peak_disconnect_time; // Peak time cleaning code mem |
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68 |
78 |
69 static void process_nmethod(nmethod *nm); |
79 static int process_nmethod(nmethod *nm); |
70 static void release_nmethod(nmethod* nm); |
80 static void release_nmethod(nmethod* nm); |
71 |
81 |
72 static void log_sweep(const char* msg, const char* format = NULL, ...); |
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73 static bool sweep_in_progress(); |
82 static bool sweep_in_progress(); |
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83 static void sweep_code_cache(); |
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84 static void request_nmethod_marking() { _request_mark_phase = true; } |
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85 static void reset_nmethod_marking() { _request_mark_phase = false; } |
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86 static bool need_marking_phase() { return _request_mark_phase; } |
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87 |
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88 static int _hotness_counter_reset_val; |
74 |
89 |
75 public: |
90 public: |
76 static long traversal_count() { return _traversals; } |
91 static long traversal_count() { return _traversals; } |
77 static int number_of_flushes() { return _number_of_flushes; } |
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78 static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } |
92 static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } |
79 static jlong total_time_sweeping() { return _total_time_sweeping; } |
93 static jlong total_time_sweeping() { return _total_time_sweeping; } |
80 static jlong peak_sweep_time() { return _peak_sweep_time; } |
94 static jlong peak_sweep_time() { return _peak_sweep_time; } |
81 static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } |
95 static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } |
82 static jlong total_disconnect_time() { return _total_disconnect_time; } |
96 static void log_sweep(const char* msg, const char* format = NULL, ...); |
83 static jlong peak_disconnect_time() { return _peak_disconnect_time; } |
97 |
84 |
98 |
85 #ifdef ASSERT |
99 #ifdef ASSERT |
86 static bool is_sweeping(nmethod* which) { return _current == which; } |
100 static bool is_sweeping(nmethod* which) { return _current == which; } |
87 // Keep track of sweeper activity in the ring buffer |
101 // Keep track of sweeper activity in the ring buffer |
88 static void record_sweep(nmethod* nm, int line); |
102 static void record_sweep(nmethod* nm, int line); |
89 static void report_events(int id, address entry); |
103 static void report_events(int id, address entry); |
90 static void report_events(); |
104 static void report_events(); |
91 #endif |
105 #endif |
92 |
106 |
93 static void scan_stacks(); // Invoked at the end of each safepoint |
107 static void mark_active_nmethods(); // Invoked at the end of each safepoint |
94 static void sweep_code_cache(); // Concurrent part of sweep job |
108 static void possibly_sweep(); // Compiler threads call this to sweep |
95 static void possibly_sweep(); // Compiler threads call this to sweep |
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96 |
109 |
97 static void notify(nmethod* nm) { |
110 static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2); |
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111 static int hotness_counter_reset_val(); |
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112 |
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113 static void notify() { |
98 // Request a new sweep of the code cache from the beginning. No |
114 // Request a new sweep of the code cache from the beginning. No |
99 // need to synchronize the setting of this flag since it only |
115 // need to synchronize the setting of this flag since it only |
100 // changes to false at safepoint so we can never overwrite it with false. |
116 // changes to false at safepoint so we can never overwrite it with false. |
101 _resweep = true; |
117 request_nmethod_marking(); |
102 } |
118 } |
103 |
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104 static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate |
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105 static void speculative_disconnect_nmethods(bool was_full); // Called by vm op to deal with alloc failure |
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106 }; |
119 }; |
107 |
120 |
108 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP |
121 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP |