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 #include "precompiled.hpp" 25 26 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 27 #include "gc/shenandoah/heuristics/shenandoahCompactHeuristics.hpp" 28 #include "gc/shenandoah/shenandoahFreeSet.hpp" 29 #include "gc/shenandoah/shenandoahHeapRegion.hpp" 30 #include "logging/log.hpp" 31 #include "logging/logTag.hpp" 32 33 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics() : ShenandoahHeuristics() { 34 SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent); 35 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent); 36 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit); 37 SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs); 38 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 10); 39 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100); 40 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay, 1000); 41 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000); 42 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold, 10); 43 } 44 45 bool ShenandoahCompactHeuristics::should_start_normal_gc() const { 46 ShenandoahHeap* heap = ShenandoahHeap::heap(); 47 48 size_t available = heap->free_set()->available(); 49 size_t threshold_bytes_allocated = heap->capacity() * ShenandoahAllocationThreshold / 100; 50 size_t min_threshold = ShenandoahMinFreeThreshold * heap->capacity() / 100; 51 52 if (available < min_threshold) { 53 log_info(gc)("Trigger: Free (" SIZE_FORMAT "M) is below minimum threshold (" SIZE_FORMAT "M)", 54 available / M, min_threshold / M); 55 return true; 56 } 57 58 if (available < threshold_bytes_allocated) { 59 log_info(gc)("Trigger: Free (" SIZE_FORMAT "M) is lower than allocated recently (" SIZE_FORMAT "M)", 60 available / M, threshold_bytes_allocated / M); 61 return true; 62 } 63 64 size_t bytes_allocated = heap->bytes_allocated_since_gc_start(); 65 if (bytes_allocated > threshold_bytes_allocated) { 66 log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "M) is larger than allocation threshold (" SIZE_FORMAT "M)", 67 bytes_allocated / M, threshold_bytes_allocated / M); 68 return true; 69 } 70 71 return ShenandoahHeuristics::should_start_normal_gc(); 72 } 73 74 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset, 75 RegionData* data, size_t size, 76 size_t actual_free) { 77 // Do not select too large CSet that would overflow the available free space 78 size_t max_cset = actual_free * 3 / 4; 79 80 log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "M, Max CSet: " SIZE_FORMAT "M", 81 actual_free / M, max_cset / M); 82 83 size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100; 84 85 size_t live_cset = 0; 86 for (size_t idx = 0; idx < size; idx++) { 87 ShenandoahHeapRegion* r = data[idx]._region; 88 size_t new_cset = live_cset + r->get_live_data_bytes(); 89 if (new_cset < max_cset && r->garbage() > threshold) { 90 live_cset = new_cset; 91 cset->add_region(r); 92 } 93 } 94 } 95 96 const char* ShenandoahCompactHeuristics::name() { 97 return "compact"; 98 } 99 100 bool ShenandoahCompactHeuristics::is_diagnostic() { 101 return false; 102 } 103 104 bool ShenandoahCompactHeuristics::is_experimental() { 105 return false; 106 }