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/heuristics/shenandoahPassiveHeuristics.hpp" 27 #include "gc/shenandoah/shenandoahCollectionSet.hpp" 28 #include "gc/shenandoah/shenandoahHeapRegion.hpp" 29 #include "logging/log.hpp" 30 #include "logging/logTag.hpp" 31 32 ShenandoahPassiveHeuristics::ShenandoahPassiveHeuristics() : ShenandoahHeuristics() { 33 // Do not allow concurrent cycles. 34 FLAG_SET_DEFAULT(ExplicitGCInvokesConcurrent, false); 35 FLAG_SET_DEFAULT(ShenandoahImplicitGCInvokesConcurrent, false); 36 37 // Passive runs with max speed, reacts on allocation failure. 38 FLAG_SET_DEFAULT(ShenandoahPacing, false); 39 40 // No need for evacuation reserve with Full GC, only for Degenerated GC. 41 if (!ShenandoahDegeneratedGC) { 42 SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahEvacReserve, 0); 43 } 44 45 // Disable known barriers by default. 46 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahSATBBarrier); 47 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahKeepAliveBarrier); 48 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahWriteBarrier); 49 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahReadBarrier); 50 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStoreValEnqueueBarrier); 51 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahStoreValReadBarrier); 52 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCASBarrier); 53 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahAcmpBarrier); 54 SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahCloneBarrier); 55 56 // Final configuration checks 57 // No barriers are required to run. 58 } 59 60 bool ShenandoahPassiveHeuristics::should_start_normal_gc() const { 61 // Never do concurrent GCs. 62 return false; 63 } 64 65 bool ShenandoahPassiveHeuristics::should_process_references() { 66 // Always process references, if we can. 67 return can_process_references(); 68 } 69 70 bool ShenandoahPassiveHeuristics::should_unload_classes() { 71 // Always unload classes, if we can. 72 return can_unload_classes(); 73 } 74 75 bool ShenandoahPassiveHeuristics::should_degenerate_cycle() { 76 // Always fail to Degenerated GC, if enabled 77 return ShenandoahDegeneratedGC; 78 } 79 80 void ShenandoahPassiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset, 81 RegionData* data, size_t size, 82 size_t actual_free) { 83 assert(ShenandoahDegeneratedGC, "This path is only taken for Degenerated GC"); 84 85 // Do not select too large CSet that would overflow the available free space. 86 // Take at least the entire evacuation reserve, and be free to overflow to free space. 87 size_t capacity = ShenandoahHeap::heap()->capacity(); 88 size_t available = MAX2(ShenandoahEvacReserve * capacity / 100, actual_free); 89 size_t max_cset = (size_t)(available / ShenandoahEvacWaste); 90 91 log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "M, Max CSet: " SIZE_FORMAT "M", 92 actual_free / M, max_cset / M); 93 94 size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100; 95 96 size_t live_cset = 0; 97 for (size_t idx = 0; idx < size; idx++) { 98 ShenandoahHeapRegion* r = data[idx]._region; 99 size_t new_cset = live_cset + r->get_live_data_bytes(); 100 if (new_cset < max_cset && r->garbage() > threshold) { 101 live_cset = new_cset; 102 cset->add_region(r); 103 } 104 } 105 } 106 107 const char* ShenandoahPassiveHeuristics::name() { 108 return "passive"; 109 } 110 111 bool ShenandoahPassiveHeuristics::is_diagnostic() { 112 return true; 113 } 114 115 bool ShenandoahPassiveHeuristics::is_experimental() { 116 return false; 117 }