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 "memory/allocation.hpp" 29 30 class ShenandoahHeap; 31 32 #define PACING_PROGRESS_UNINIT (-1) 33 #define PACING_PROGRESS_ZERO ( 0) 34 35 /** 36 * ShenandoahPacer provides allocation pacing mechanism. 37 * 38 * Currently it implements simple tax-and-spend pacing policy: GC threads provide 39 * credit, allocating thread spend the credit, or stall when credit is not available. 40 */ 41 class ShenandoahPacer : public CHeapObj<mtGC> { 42 private: 43 ShenandoahHeap* _heap; 44 BinaryMagnitudeSeq _delays; 45 TruncatedSeq* _progress_history; 46 47 // Set once per phase 48 volatile intptr_t _epoch; 49 volatile double _tax_rate; 50 51 // Heavily updated, protect from accidental false sharing 52 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile intptr_t)); 53 volatile intptr_t _budget; 54 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0); 55 56 // Heavily updated, protect from accidental false sharing 57 DEFINE_PAD_MINUS_SIZE(2, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile intptr_t)); 58 volatile intptr_t _progress; 59 DEFINE_PAD_MINUS_SIZE(3, DEFAULT_CACHE_LINE_SIZE, 0); 60 61 public: ShenandoahPacer(ShenandoahHeap * heap)62 ShenandoahPacer(ShenandoahHeap* heap) : 63 _heap(heap), 64 _progress_history(new TruncatedSeq(5)), 65 _epoch(0), 66 _tax_rate(1), 67 _budget(0), 68 _progress(PACING_PROGRESS_UNINIT) {} 69 70 void setup_for_idle(); 71 void setup_for_mark(); 72 void setup_for_evac(); 73 void setup_for_updaterefs(); 74 void setup_for_traversal(); 75 76 inline void report_mark(size_t words); 77 inline void report_evac(size_t words); 78 inline void report_updaterefs(size_t words); 79 80 inline void report_alloc(size_t words); 81 82 bool claim_for_alloc(size_t words, bool force); 83 void pace_for_alloc(size_t words); 84 void unpace_for_alloc(intptr_t epoch, size_t words); 85 86 intptr_t epoch(); 87 88 void print_on(outputStream* out) const; 89 90 private: 91 inline void report_internal(size_t words); 92 inline void report_progress_internal(size_t words); 93 94 void restart_with(size_t non_taxable_bytes, double tax_rate); 95 96 size_t update_and_get_progress_history(); 97 }; 98 99 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHPACER_HPP 100