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/shenandoahHeap.inline.hpp" 29 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp" 30 #include "logging/log.hpp" 31 #include "logging/logTag.hpp" 32 33 bool ShenandoahPassiveHeuristics::should_start_gc() const { 34 // Never do concurrent GCs. 35 return false; 36 } 37 38 bool ShenandoahPassiveHeuristics::should_process_references() { 39 // Always process references, if we can. 40 return can_process_references(); 41 } 42 43 bool ShenandoahPassiveHeuristics::should_unload_classes() { 44 // Always unload classes, if we can. 45 return can_unload_classes(); 46 } 47 48 bool ShenandoahPassiveHeuristics::should_degenerate_cycle() { 49 // Always fail to Degenerated GC, if enabled 50 return ShenandoahDegeneratedGC; 51 } 52 53 void ShenandoahPassiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset, 54 RegionData* data, size_t size, 55 size_t actual_free) { 56 assert(ShenandoahDegeneratedGC, "This path is only taken for Degenerated GC"); 57 58 // Do not select too large CSet that would overflow the available free space. 59 // Take at least the entire evacuation reserve, and be free to overflow to free space. 60 size_t capacity = ShenandoahHeap::heap()->max_capacity(); 61 size_t available = MAX2(capacity / 100 * ShenandoahEvacReserve, actual_free); 62 size_t max_cset = (size_t)(available / ShenandoahEvacWaste); 63 64 log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s", 65 byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free), 66 byte_size_in_proper_unit(max_cset), proper_unit_for_byte_size(max_cset)); 67 68 size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100; 69 70 size_t live_cset = 0; 71 for (size_t idx = 0; idx < size; idx++) { 72 ShenandoahHeapRegion* r = data[idx]._region; 73 size_t new_cset = live_cset + r->get_live_data_bytes(); 74 if (new_cset < max_cset && r->garbage() > threshold) { 75 live_cset = new_cset; 76 cset->add_region(r); 77 } 78 } 79 }