1 /* 2 * Copyright (c) 2018, Red Hat, Inc. All rights reserved. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHPACER_HPP 25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHPACER_HPP 26 27 #include "gc/shenandoah/shenandoahNumberSeq.hpp" 28 #include "gc/shenandoah/shenandoahPadding.hpp" 29 #include "memory/allocation.hpp" 30 31 class ShenandoahHeap; 32 33 #define PACING_PROGRESS_UNINIT (-1) 34 #define PACING_PROGRESS_ZERO ( 0) 35 36 /** 37 * ShenandoahPacer provides allocation pacing mechanism. 38 * 39 * Currently it implements simple tax-and-spend pacing policy: GC threads provide 40 * credit, allocating thread spend the credit, or stall when credit is not available. 41 */ 42 class ShenandoahPacer : public CHeapObj<mtGC> { 43 private: 44 ShenandoahHeap* _heap; 45 double _last_time; 46 TruncatedSeq* _progress_history; 47 Monitor* _wait_monitor; 48 ShenandoahSharedFlag _need_notify_waiters; 49 50 // Set once per phase 51 volatile intptr_t _epoch; 52 volatile double _tax_rate; 53 54 // Heavily updated, protect from accidental false sharing 55 shenandoah_padding(0); 56 volatile intptr_t _budget; 57 shenandoah_padding(1); 58 59 // Heavily updated, protect from accidental false sharing 60 shenandoah_padding(2); 61 volatile intptr_t _progress; 62 shenandoah_padding(3); 63 64 public: ShenandoahPacer(ShenandoahHeap * heap)65 ShenandoahPacer(ShenandoahHeap* heap) : 66 _heap(heap), 67 _last_time(os::elapsedTime()), 68 _progress_history(new TruncatedSeq(5)), 69 _wait_monitor(new Monitor(Mutex::leaf, "_wait_monitor", true, Monitor::_safepoint_check_always)), 70 _epoch(0), 71 _tax_rate(1), 72 _budget(0), 73 _progress(PACING_PROGRESS_UNINIT) {} 74 75 void setup_for_idle(); 76 void setup_for_mark(); 77 void setup_for_evac(); 78 void setup_for_updaterefs(); 79 80 void setup_for_reset(); 81 void setup_for_preclean(); 82 83 inline void report_mark(size_t words); 84 inline void report_evac(size_t words); 85 inline void report_updaterefs(size_t words); 86 87 inline void report_alloc(size_t words); 88 89 bool claim_for_alloc(size_t words, bool force); 90 void pace_for_alloc(size_t words); 91 void unpace_for_alloc(intptr_t epoch, size_t words); 92 93 void notify_waiters(); 94 95 intptr_t epoch(); 96 97 void flush_stats_to_cycle(); 98 void print_cycle_on(outputStream* out); 99 100 private: 101 inline void report_internal(size_t words); 102 inline void report_progress_internal(size_t words); 103 104 inline void add_budget(size_t words); 105 void restart_with(size_t non_taxable_bytes, double tax_rate); 106 107 size_t update_and_get_progress_history(); 108 109 void wait(size_t time_ms); 110 }; 111 112 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHPACER_HPP 113