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comparison src/share/vm/runtime/sweeper.hpp @ 12324:510fbd28919c

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8020151: PSR:PERF Large performance regressions when code cache is filled Summary: Code cache sweeping based on method hotness; removed speculatively disconnect Reviewed-by: kvn, iveresov
author anoll
date Fri, 27 Sep 2013 10:50:55 +0200
parents 5888334c9c24
children 78da3894b86f
comparison
equal deleted inserted replaced
12323:c9ccd7b85f20 12324:510fbd28919c
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
32 // 1) mark active nmethods
33 // Is done in 'mark_active_nmethods()'. This function is called at a
34 // safepoint and marks all nmethods that are active on a thread's stack.
35 // 2) sweep nmethods
36 // Is done in sweep_code_cache(). This function is the only place in the
37 // sweeper where memory is reclaimed. Note that sweep_code_cache() is not
38 // called at a safepoint. However, sweep_code_cache() stops executing if
39 // another thread requests a safepoint. Consequently, 'mark_active_nmethods()'
40 // and sweep_code_cache() cannot execute at the same time.
41 // To reclaim memory, nmethods are first marked as 'not-entrant'. Methods can
42 // be made not-entrant by (i) the sweeper, (ii) deoptimization, (iii) dependency
43 // invalidation, and (iv) being replaced be a different method version (tiered
44 // compilation). Not-entrant nmethod cannot be called by Java threads, but they
45 // can still be active on the stack. To ensure that active nmethod are not reclaimed,
46 // we have to wait until the next marking phase has completed. If a not-entrant
47 // nmethod was NOT marked as active, it can be converted to 'zombie' state. To safely
48 // remove the nmethod, all inline caches (IC) that point to the the nmethod must be
49 // cleared. After that, the nmethod can be evicted from the code cache. Each nmethod's
50 // state change happens during separate sweeps. It may take at least 3 sweeps before an
51 // nmethod's space is freed. Sweeping is currently done by compiler threads between
52 // compilations or at least each 5 sec (NmethodSweepCheckInterval) when the code cache
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.
50
51 // These are set during a flush, a VM-operation
52 static long _last_flush_traversal_id; // trav number at last flush unloading
53 static jlong _last_full_flush_time; // timestamp of last emergency unloading
54
55 // These are synchronized by the _sweep_started token
56 static int _highest_marked; // highest compile id dumped at last emergency unloading
57 static int _dead_compile_ids; // number of compile ids that where not in the cache last flush
58 71
59 // Stat counters 72 // Stat counters
60 static int _number_of_flushes; // Total of full traversals caused by full cache
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
67 static jlong _peak_disconnect_time; // Peak time cleaning code mem
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, ...);
73 static bool sweep_in_progress(); 82 static bool sweep_in_progress();
83 static void sweep_code_cache();
84 static void request_nmethod_marking() { _request_mark_phase = true; }
85 static void reset_nmethod_marking() { _request_mark_phase = false; }
86 static bool need_marking_phase() { return _request_mark_phase; }
87
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; }
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
96 109
97 static void notify(nmethod* nm) { 110 static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2);
111 static int hotness_counter_reset_val();
112
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
104 static void handle_full_code_cache(bool is_full); // Called by compilers who fail to allocate
105 static void speculative_disconnect_nmethods(bool was_full); // Called by vm op to deal with alloc failure
106 }; 119 };
107 120
108 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP 121 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP