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 */ 24 25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP 26 #define SHARE_VM_RUNTIME_SWEEPER_HPP 27 28 // An NmethodSweeper is an incremental cleaner for: 29 // - cleanup inline caches 30 // - reclamation of unreferences zombie nmethods 31 // 32 33 class NMethodSweeper : public AllStatic { 34 static long _traversals; // Stack scan count, also sweep ID. 35 static nmethod* _current; // Current nmethod 36 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache 37 static int _flushed_count; // Nof. nmethods flushed in current sweep 38 static int _zombified_count; // Nof. nmethods made zombie in current sweep 39 static int _marked_count; // Nof. nmethods marked for reclaim in current sweep 40 41 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 43 44 //The following are reset in scan_stacks and synchronized by the safepoint 45 static bool _resweep; // Indicates that a change has happend and we want another sweep, 46 // 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 48 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 59 // 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 62 static jlong _total_time_sweeping; // Accumulated time sweeping 63 static jlong _total_time_this_sweep; // Total time this sweep 64 static jlong _peak_sweep_time; // Peak time for a full sweep 65 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 69 static void process_nmethod(nmethod *nm); 70 static void release_nmethod(nmethod* nm); 71 72 static void log_sweep(const char* msg, const char* format = NULL, ...); 73 static bool sweep_in_progress(); 74 75 public: 76 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; } 79 static jlong total_time_sweeping() { return _total_time_sweeping; } 80 static jlong peak_sweep_time() { return _peak_sweep_time; } 81 static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } 82 static jlong total_disconnect_time() { return _total_disconnect_time; } 83 static jlong peak_disconnect_time() { return _peak_disconnect_time; } 84 85 #ifdef ASSERT 86 static bool is_sweeping(nmethod* which) { return _current == which; } 87 // Keep track of sweeper activity in the ring buffer 88 static void record_sweep(nmethod* nm, int line); 89 static void report_events(int id, address entry); 90 static void report_events(); 91 #endif 92 93 static void scan_stacks(); // Invoked at the end of each safepoint 94 static void sweep_code_cache(); // Concurrent part of sweep job 95 static void possibly_sweep(); // Compiler threads call this to sweep 96 97 static void notify(nmethod* nm) { 98 // Request a new sweep of the code cache from the beginning. No 99 // 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. 101 _resweep = true; 102 } 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 }; 107 108 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP | 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 */ 24 25 #ifndef SHARE_VM_RUNTIME_SWEEPER_HPP 26 #define SHARE_VM_RUNTIME_SWEEPER_HPP 27 28 // An NmethodSweeper is an incremental cleaner for: 29 // - cleanup inline caches 30 // - reclamation of nmethods 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. 54 55 class NMethodSweeper : public AllStatic { 56 static long _traversals; // Stack scan count, also sweep ID. 57 static nmethod* _current; // Current nmethod 58 static int _seen; // Nof. nmethod we have currently processed in current pass of CodeCache 59 static int _flushed_count; // Nof. nmethods flushed in current sweep 60 static int _zombified_count; // Nof. nmethods made zombie in current sweep 61 static int _marked_count; // Nof. nmethods marked for reclaim in current sweep 62 63 static volatile int _invocations; // No. of invocations left until we are completed with this pass 64 static volatile int _sweep_started; // Flag to control conc sweeper 65 66 //The following are reset in mark_active_nmethods and synchronized by the safepoint 67 static bool _request_mark_phase; // Indicates that a change has happend and we need another mark pahse, 68 // always checked and reset at a safepoint so memory will be in sync. 69 static int _locked_seen; // Number of locked nmethods encountered during the scan 70 static int _not_entrant_seen_on_stack; // Number of not entrant nmethod were are still on stack 71 72 // Stat counters 73 static int _total_nof_methods_reclaimed; // Accumulated nof methods flushed 74 static jlong _total_time_sweeping; // Accumulated time sweeping 75 static jlong _total_time_this_sweep; // Total time this sweep 76 static jlong _peak_sweep_time; // Peak time for a full sweep 77 static jlong _peak_sweep_fraction_time; // Peak time sweeping one fraction 78 79 static int process_nmethod(nmethod *nm); 80 static void release_nmethod(nmethod* nm); 81 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; 89 90 public: 91 static long traversal_count() { return _traversals; } 92 static int total_nof_methods_reclaimed() { return _total_nof_methods_reclaimed; } 93 static jlong total_time_sweeping() { return _total_time_sweeping; } 94 static jlong peak_sweep_time() { return _peak_sweep_time; } 95 static jlong peak_sweep_fraction_time() { return _peak_sweep_fraction_time; } 96 static void log_sweep(const char* msg, const char* format = NULL, ...); 97 98 99 #ifdef ASSERT 100 static bool is_sweeping(nmethod* which) { return _current == which; } 101 // Keep track of sweeper activity in the ring buffer 102 static void record_sweep(nmethod* nm, int line); 103 static void report_events(int id, address entry); 104 static void report_events(); 105 #endif 106 107 static void mark_active_nmethods(); // Invoked at the end of each safepoint 108 static void possibly_sweep(); // Compiler threads call this to sweep 109 110 static int sort_nmethods_by_hotness(nmethod** nm1, nmethod** nm2); 111 static int hotness_counter_reset_val(); 112 113 static void notify() { 114 // Request a new sweep of the code cache from the beginning. No 115 // need to synchronize the setting of this flag since it only 116 // changes to false at safepoint so we can never overwrite it with false. 117 request_nmethod_marking(); 118 } 119 }; 120 121 #endif // SHARE_VM_RUNTIME_SWEEPER_HPP |