truffle: src/share/vm/memory/cardTableRS.cpp annotate

annotate src/share/vm/memory/cardTableRS.cpp @ 12033:bd902affe102

8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 Reviewed-by: stefank, ehelin

author	brutisso
date	Thu, 15 Aug 2013 10:05:50 +0200
parents	330dfb0476f4
children	63a4eb8bcd23 78bbf4d43a14

rev	line source
0 a61af66fc99e Initial load duke parents: diff changeset	1 /*
10271 f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
0 a61af66fc99e Initial load duke parents: diff changeset	3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
a61af66fc99e Initial load duke parents: diff changeset	4 *
a61af66fc99e Initial load duke parents: diff changeset	5 * This code is free software; you can redistribute it and/or modify it
a61af66fc99e Initial load duke parents: diff changeset	6 * under the terms of the GNU General Public License version 2 only, as
a61af66fc99e Initial load duke parents: diff changeset	7 * published by the Free Software Foundation.
a61af66fc99e Initial load duke parents: diff changeset	8 *
a61af66fc99e Initial load duke parents: diff changeset	9 * This code is distributed in the hope that it will be useful, but WITHOUT
a61af66fc99e Initial load duke parents: diff changeset	10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
a61af66fc99e Initial load duke parents: diff changeset	11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
a61af66fc99e Initial load duke parents: diff changeset	12 * version 2 for more details (a copy is included in the LICENSE file that
a61af66fc99e Initial load duke parents: diff changeset	13 * accompanied this code).
a61af66fc99e Initial load duke parents: diff changeset	14 *
a61af66fc99e Initial load duke parents: diff changeset	15 * You should have received a copy of the GNU General Public License version
a61af66fc99e Initial load duke parents: diff changeset	16 * 2 along with this work; if not, write to the Free Software Foundation,
a61af66fc99e Initial load duke parents: diff changeset	17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
a61af66fc99e Initial load duke parents: diff changeset	18 *
1552 c18cbe5936b8 6941466: Oracle rebranding changes for Hotspot repositories trims parents: 844 diff changeset	19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
c18cbe5936b8 6941466: Oracle rebranding changes for Hotspot repositories trims parents: 844 diff changeset	20 * or visit www.oracle.com if you need additional information or have any
c18cbe5936b8 6941466: Oracle rebranding changes for Hotspot repositories trims parents: 844 diff changeset	21 * questions.
0 a61af66fc99e Initial load duke parents: diff changeset	22 *
a61af66fc99e Initial load duke parents: diff changeset	23 */
a61af66fc99e Initial load duke parents: diff changeset	24
1972 f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	25 #include "precompiled.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	26 #include "memory/allocation.inline.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	27 #include "memory/cardTableRS.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	28 #include "memory/genCollectedHeap.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	29 #include "memory/generation.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	30 #include "memory/space.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	31 #include "oops/oop.inline.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	32 #include "runtime/java.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	33 #include "runtime/os.hpp"
8001 db9981fd3124 8005915: Unify SERIALGC and INCLUDE_ALTERNATE_GCS jprovino parents: 6725 diff changeset	34 #include "utilities/macros.hpp"
db9981fd3124 8005915: Unify SERIALGC and INCLUDE_ALTERNATE_GCS jprovino parents: 6725 diff changeset	35 #if INCLUDE_ALL_GCS
1972 f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	36 #include "gc_implementation/g1/concurrentMark.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	37 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
8001 db9981fd3124 8005915: Unify SERIALGC and INCLUDE_ALTERNATE_GCS jprovino parents: 6725 diff changeset	38 #endif // INCLUDE_ALL_GCS
0 a61af66fc99e Initial load duke parents: diff changeset	39
a61af66fc99e Initial load duke parents: diff changeset	40 CardTableRS::CardTableRS(MemRegion whole_heap,
a61af66fc99e Initial load duke parents: diff changeset	41 int max_covered_regions) :
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	42 GenRemSet(),
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	43 _cur_youngergen_card_val(youngergenP1_card),
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	44 _regions_to_iterate(max_covered_regions - 1)
0 a61af66fc99e Initial load duke parents: diff changeset	45 {
8001 db9981fd3124 8005915: Unify SERIALGC and INCLUDE_ALTERNATE_GCS jprovino parents: 6725 diff changeset	46 #if INCLUDE_ALL_GCS
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	47 if (UseG1GC) {
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	48 _ct_bs = new G1SATBCardTableLoggingModRefBS(whole_heap,
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	49 max_covered_regions);
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	50 } else {
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	51 _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	52 }
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	53 #else
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	54 _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	55 #endif
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	56 set_bs(_ct_bs);
10271 f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	57 _last_cur_val_in_gen = NEW_C_HEAP_ARRAY3(jbyte, GenCollectedHeap::max_gens + 1,
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	58 mtGC, 0, AllocFailStrategy::RETURN_NULL);
0 a61af66fc99e Initial load duke parents: diff changeset	59 if (_last_cur_val_in_gen == NULL) {
10271 f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	60 vm_exit_during_initialization("Could not create last_cur_val_in_gen array.");
0 a61af66fc99e Initial load duke parents: diff changeset	61 }
a61af66fc99e Initial load duke parents: diff changeset	62 for (int i = 0; i < GenCollectedHeap::max_gens + 1; i++) {
a61af66fc99e Initial load duke parents: diff changeset	63 _last_cur_val_in_gen[i] = clean_card_val();
a61af66fc99e Initial load duke parents: diff changeset	64 }
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	65 _ct_bs->set_CTRS(this);
0 a61af66fc99e Initial load duke parents: diff changeset	66 }
a61af66fc99e Initial load duke parents: diff changeset	67
10271 f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	68 CardTableRS::~CardTableRS() {
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	69 if (_ct_bs) {
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	70 delete _ct_bs;
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	71 _ct_bs = NULL;
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	72 }
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	73 if (_last_cur_val_in_gen) {
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	74 FREE_C_HEAP_ARRAY(jbyte, _last_cur_val_in_gen, mtInternal);
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	75 }
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	76 }
f9be75d21404 8012902: remove use of global operator new - take 2 minqi parents: 10135 diff changeset	77
0 a61af66fc99e Initial load duke parents: diff changeset	78 void CardTableRS::resize_covered_region(MemRegion new_region) {
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	79 _ct_bs->resize_covered_region(new_region);
0 a61af66fc99e Initial load duke parents: diff changeset	80 }
a61af66fc99e Initial load duke parents: diff changeset	81
a61af66fc99e Initial load duke parents: diff changeset	82 jbyte CardTableRS::find_unused_youngergenP_card_value() {
a61af66fc99e Initial load duke parents: diff changeset	83 for (jbyte v = youngergenP1_card;
a61af66fc99e Initial load duke parents: diff changeset	84 v < cur_youngergen_and_prev_nonclean_card;
a61af66fc99e Initial load duke parents: diff changeset	85 v++) {
a61af66fc99e Initial load duke parents: diff changeset	86 bool seen = false;
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	87 for (int g = 0; g < _regions_to_iterate; g++) {
0 a61af66fc99e Initial load duke parents: diff changeset	88 if (_last_cur_val_in_gen[g] == v) {
a61af66fc99e Initial load duke parents: diff changeset	89 seen = true;
a61af66fc99e Initial load duke parents: diff changeset	90 break;
a61af66fc99e Initial load duke parents: diff changeset	91 }
a61af66fc99e Initial load duke parents: diff changeset	92 }
a61af66fc99e Initial load duke parents: diff changeset	93 if (!seen) return v;
a61af66fc99e Initial load duke parents: diff changeset	94 }
a61af66fc99e Initial load duke parents: diff changeset	95 ShouldNotReachHere();
a61af66fc99e Initial load duke parents: diff changeset	96 return 0;
a61af66fc99e Initial load duke parents: diff changeset	97 }
a61af66fc99e Initial load duke parents: diff changeset	98
a61af66fc99e Initial load duke parents: diff changeset	99 void CardTableRS::prepare_for_younger_refs_iterate(bool parallel) {
a61af66fc99e Initial load duke parents: diff changeset	100 // Parallel or sequential, we must always set the prev to equal the
a61af66fc99e Initial load duke parents: diff changeset	101 // last one written.
a61af66fc99e Initial load duke parents: diff changeset	102 if (parallel) {
a61af66fc99e Initial load duke parents: diff changeset	103 // Find a parallel value to be used next.
a61af66fc99e Initial load duke parents: diff changeset	104 jbyte next_val = find_unused_youngergenP_card_value();
a61af66fc99e Initial load duke parents: diff changeset	105 set_cur_youngergen_card_val(next_val);
a61af66fc99e Initial load duke parents: diff changeset	106
a61af66fc99e Initial load duke parents: diff changeset	107 } else {
a61af66fc99e Initial load duke parents: diff changeset	108 // In an sequential traversal we will always write youngergen, so that
a61af66fc99e Initial load duke parents: diff changeset	109 // the inline barrier is correct.
a61af66fc99e Initial load duke parents: diff changeset	110 set_cur_youngergen_card_val(youngergen_card);
a61af66fc99e Initial load duke parents: diff changeset	111 }
a61af66fc99e Initial load duke parents: diff changeset	112 }
a61af66fc99e Initial load duke parents: diff changeset	113
a61af66fc99e Initial load duke parents: diff changeset	114 void CardTableRS::younger_refs_iterate(Generation* g,
a61af66fc99e Initial load duke parents: diff changeset	115 OopsInGenClosure* blk) {
a61af66fc99e Initial load duke parents: diff changeset	116 _last_cur_val_in_gen[g->level()+1] = cur_youngergen_card_val();
a61af66fc99e Initial load duke parents: diff changeset	117 g->younger_refs_iterate(blk);
a61af66fc99e Initial load duke parents: diff changeset	118 }
a61af66fc99e Initial load duke parents: diff changeset	119
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	120 inline bool ClearNoncleanCardWrapper::clear_card(jbyte* entry) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	121 if (_is_par) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	122 return clear_card_parallel(entry);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	123 } else {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	124 return clear_card_serial(entry);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	125 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	126 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	127
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	128 inline bool ClearNoncleanCardWrapper::clear_card_parallel(jbyte* entry) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	129 while (true) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	130 // In the parallel case, we may have to do this several times.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	131 jbyte entry_val = *entry;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	132 assert(entry_val != CardTableRS::clean_card_val(),
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	133 "We shouldn't be looking at clean cards, and this should "
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	134 "be the only place they get cleaned.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	135 if (CardTableRS::card_is_dirty_wrt_gen_iter(entry_val)
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	136 \|\| _ct->is_prev_youngergen_card_val(entry_val)) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	137 jbyte res =
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	138 Atomic::cmpxchg(CardTableRS::clean_card_val(), entry, entry_val);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	139 if (res == entry_val) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	140 break;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	141 } else {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	142 assert(res == CardTableRS::cur_youngergen_and_prev_nonclean_card,
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	143 "The CAS above should only fail if another thread did "
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	144 "a GC write barrier.");
0 a61af66fc99e Initial load duke parents: diff changeset	145 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	146 } else if (entry_val ==
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	147 CardTableRS::cur_youngergen_and_prev_nonclean_card) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	148 // Parallelism shouldn't matter in this case. Only the thread
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	149 // assigned to scan the card should change this value.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	150 *entry = _ct->cur_youngergen_card_val();
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	151 break;
0 a61af66fc99e Initial load duke parents: diff changeset	152 } else {
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	153 assert(entry_val == _ct->cur_youngergen_card_val(),
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	154 "Should be the only possibility.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	155 // In this case, the card was clean before, and become
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	156 // cur_youngergen only because of processing of a promoted object.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	157 // We don't have to look at the card.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	158 return false;
0 a61af66fc99e Initial load duke parents: diff changeset	159 }
a61af66fc99e Initial load duke parents: diff changeset	160 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	161 return true;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	162 }
0 a61af66fc99e Initial load duke parents: diff changeset	163
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	164
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	165 inline bool ClearNoncleanCardWrapper::clear_card_serial(jbyte* entry) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	166 jbyte entry_val = *entry;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	167 assert(entry_val != CardTableRS::clean_card_val(),
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	168 "We shouldn't be looking at clean cards, and this should "
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	169 "be the only place they get cleaned.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	170 assert(entry_val != CardTableRS::cur_youngergen_and_prev_nonclean_card,
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	171 "This should be possible in the sequential case.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	172 *entry = CardTableRS::clean_card_val();
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	173 return true;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	174 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	175
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	176 ClearNoncleanCardWrapper::ClearNoncleanCardWrapper(
3357 fc2b798ab316 6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests ysr parents: 3293 diff changeset	177 DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct) :
0 a61af66fc99e Initial load duke parents: diff changeset	178 _dirty_card_closure(dirty_card_closure), _ct(ct) {
4095 bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	179 // Cannot yet substitute active_workers for n_par_threads
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	180 // in the case where parallelism is being turned off by
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	181 // setting n_par_threads to 0.
0 a61af66fc99e Initial load duke parents: diff changeset	182 _is_par = (SharedHeap::heap()->n_par_threads() > 0);
4095 bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	183 assert(!_is_par \|\|
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	184 (SharedHeap::heap()->n_par_threads() ==
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	185 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	186 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	187
5939 c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	188 bool ClearNoncleanCardWrapper::is_word_aligned(jbyte* entry) {
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	189 return (((intptr_t)entry) & (BytesPerWord-1)) == 0;
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	190 }
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	191
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	192 void ClearNoncleanCardWrapper::do_MemRegion(MemRegion mr) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	193 assert(mr.word_size() > 0, "Error");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	194 assert(_ct->is_aligned(mr.start()), "mr.start() should be card aligned");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	195 // mr.end() may not necessarily be card aligned.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	196 jbyte* cur_entry = _ct->byte_for(mr.last());
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	197 const jbyte* limit = _ct->byte_for(mr.start());
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	198 HeapWord* end_of_non_clean = mr.end();
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	199 HeapWord* start_of_non_clean = end_of_non_clean;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	200 while (cur_entry >= limit) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	201 HeapWord* cur_hw = _ct->addr_for(cur_entry);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	202 if ((*cur_entry != CardTableRS::clean_card_val()) && clear_card(cur_entry)) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	203 // Continue the dirty range by opening the
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	204 // dirty window one card to the left.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	205 start_of_non_clean = cur_hw;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	206 } else {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	207 // We hit a "clean" card; process any non-empty
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	208 // "dirty" range accumulated so far.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	209 if (start_of_non_clean < end_of_non_clean) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	210 const MemRegion mrd(start_of_non_clean, end_of_non_clean);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	211 _dirty_card_closure->do_MemRegion(mrd);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	212 }
5939 c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	213
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	214 // fast forward through potential continuous whole-word range of clean cards beginning at a word-boundary
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	215 if (is_word_aligned(cur_entry)) {
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	216 jbyte* cur_row = cur_entry - BytesPerWord;
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	217 while (cur_row >= limit && ((intptr_t)cur_row) == CardTableRS::clean_card_row()) {
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	218 cur_row -= BytesPerWord;
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	219 }
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	220 cur_entry = cur_row + BytesPerWord;
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	221 cur_hw = _ct->addr_for(cur_entry);
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	222 }
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	223
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	224 // Reset the dirty window, while continuing to look
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	225 // for the next dirty card that will start a
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	226 // new dirty window.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	227 end_of_non_clean = cur_hw;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	228 start_of_non_clean = cur_hw;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	229 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	230 // Note that "cur_entry" leads "start_of_non_clean" in
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	231 // its leftward excursion after this point
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	232 // in the loop and, when we hit the left end of "mr",
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	233 // will point off of the left end of the card-table
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	234 // for "mr".
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	235 cur_entry--;
0 a61af66fc99e Initial load duke parents: diff changeset	236 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	237 // If the first card of "mr" was dirty, we will have
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	238 // been left with a dirty window, co-initial with "mr",
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	239 // which we now process.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	240 if (start_of_non_clean < end_of_non_clean) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	241 const MemRegion mrd(start_of_non_clean, end_of_non_clean);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	242 _dirty_card_closure->do_MemRegion(mrd);
0 a61af66fc99e Initial load duke parents: diff changeset	243 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	244 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	245
0 a61af66fc99e Initial load duke parents: diff changeset	246 // clean (by dirty->clean before) ==> cur_younger_gen
a61af66fc99e Initial load duke parents: diff changeset	247 // dirty ==> cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	248 // precleaned ==> cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	249 // prev-younger-gen ==> cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	250 // cur-younger-gen ==> cur_younger_gen
a61af66fc99e Initial load duke parents: diff changeset	251 // cur_youngergen_and_prev_nonclean_card ==> no change.
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	252 void CardTableRS::write_ref_field_gc_par(void* field, oop new_val) {
0 a61af66fc99e Initial load duke parents: diff changeset	253 jbyte* entry = ct_bs()->byte_for(field);
a61af66fc99e Initial load duke parents: diff changeset	254 do {
a61af66fc99e Initial load duke parents: diff changeset	255 jbyte entry_val = *entry;
a61af66fc99e Initial load duke parents: diff changeset	256 // We put this first because it's probably the most common case.
a61af66fc99e Initial load duke parents: diff changeset	257 if (entry_val == clean_card_val()) {
a61af66fc99e Initial load duke parents: diff changeset	258 // No threat of contention with cleaning threads.
a61af66fc99e Initial load duke parents: diff changeset	259 *entry = cur_youngergen_card_val();
a61af66fc99e Initial load duke parents: diff changeset	260 return;
a61af66fc99e Initial load duke parents: diff changeset	261 } else if (card_is_dirty_wrt_gen_iter(entry_val)
a61af66fc99e Initial load duke parents: diff changeset	262 \|\| is_prev_youngergen_card_val(entry_val)) {
a61af66fc99e Initial load duke parents: diff changeset	263 // Mark it as both cur and prev youngergen; card cleaning thread will
a61af66fc99e Initial load duke parents: diff changeset	264 // eventually remove the previous stuff.
a61af66fc99e Initial load duke parents: diff changeset	265 jbyte new_val = cur_youngergen_and_prev_nonclean_card;
a61af66fc99e Initial load duke parents: diff changeset	266 jbyte res = Atomic::cmpxchg(new_val, entry, entry_val);
a61af66fc99e Initial load duke parents: diff changeset	267 // Did the CAS succeed?
a61af66fc99e Initial load duke parents: diff changeset	268 if (res == entry_val) return;
a61af66fc99e Initial load duke parents: diff changeset	269 // Otherwise, retry, to see the new value.
a61af66fc99e Initial load duke parents: diff changeset	270 continue;
a61af66fc99e Initial load duke parents: diff changeset	271 } else {
a61af66fc99e Initial load duke parents: diff changeset	272 assert(entry_val == cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	273 \|\| entry_val == cur_youngergen_card_val(),
a61af66fc99e Initial load duke parents: diff changeset	274 "should be only possibilities.");
a61af66fc99e Initial load duke parents: diff changeset	275 return;
a61af66fc99e Initial load duke parents: diff changeset	276 }
a61af66fc99e Initial load duke parents: diff changeset	277 } while (true);
a61af66fc99e Initial load duke parents: diff changeset	278 }
a61af66fc99e Initial load duke parents: diff changeset	279
a61af66fc99e Initial load duke parents: diff changeset	280 void CardTableRS::younger_refs_in_space_iterate(Space* sp,
a61af66fc99e Initial load duke parents: diff changeset	281 OopsInGenClosure* cl) {
3293 1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	282 const MemRegion urasm = sp->used_region_at_save_marks();
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	283 #ifdef ASSERT
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	284 // Convert the assertion check to a warning if we are running
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	285 // CMS+ParNew until related bug is fixed.
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	286 MemRegion ur = sp->used_region();
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	287 assert(ur.contains(urasm) \|\| (UseConcMarkSweepGC && UseParNewGC),
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	288 err_msg("Did you forget to call save_marks()? "
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	289 "[" PTR_FORMAT ", " PTR_FORMAT ") is not contained in "
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	290 "[" PTR_FORMAT ", " PTR_FORMAT ")",
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	291 urasm.start(), urasm.end(), ur.start(), ur.end()));
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	292 // In the case of CMS+ParNew, issue a warning
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	293 if (!ur.contains(urasm)) {
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	294 assert(UseConcMarkSweepGC && UseParNewGC, "Tautology: see assert above");
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	295 warning("CMS+ParNew: Did you forget to call save_marks()? "
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	296 "[" PTR_FORMAT ", " PTR_FORMAT ") is not contained in "
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	297 "[" PTR_FORMAT ", " PTR_FORMAT ")",
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	298 urasm.start(), urasm.end(), ur.start(), ur.end());
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	299 MemRegion ur2 = sp->used_region();
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	300 MemRegion urasm2 = sp->used_region_at_save_marks();
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	301 if (!ur.equals(ur2)) {
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	302 warning("CMS+ParNew: Flickering used_region()!!");
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	303 }
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	304 if (!urasm.equals(urasm2)) {
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	305 warning("CMS+ParNew: Flickering used_region_at_save_marks()!!");
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	306 }
3357 fc2b798ab316 6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests ysr parents: 3293 diff changeset	307 ShouldNotReachHere();
3293 1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	308 }
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	309 #endif
3357 fc2b798ab316 6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests ysr parents: 3293 diff changeset	310 _ct_bs->non_clean_card_iterate_possibly_parallel(sp, urasm, cl, this);
0 a61af66fc99e Initial load duke parents: diff changeset	311 }
a61af66fc99e Initial load duke parents: diff changeset	312
12033 bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	313 void CardTableRS::clear_into_younger(Generation* old_gen) {
bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	314 assert(old_gen->level() == 1, "Should only be called for the old generation");
bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	315 // The card tables for the youngest gen need never be cleared.
0 a61af66fc99e Initial load duke parents: diff changeset	316 // There's a bit of subtlety in the clear() and invalidate()
a61af66fc99e Initial load duke parents: diff changeset	317 // methods that we exploit here and in invalidate_or_clear()
a61af66fc99e Initial load duke parents: diff changeset	318 // below to avoid missing cards at the fringes. If clear() or
a61af66fc99e Initial load duke parents: diff changeset	319 // invalidate() are changed in the future, this code should
a61af66fc99e Initial load duke parents: diff changeset	320 // be revisited. 20040107.ysr
12030 330dfb0476f4 8022800: Use specific generations rather than generation iteration brutisso parents: 10271 diff changeset	321 clear(old_gen->prev_used_region());
0 a61af66fc99e Initial load duke parents: diff changeset	322 }
a61af66fc99e Initial load duke parents: diff changeset	323
12033 bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	324 void CardTableRS::invalidate_or_clear(Generation* old_gen) {
bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	325 assert(old_gen->level() == 1, "Should only be called for the old generation");
bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	326 // Invalidate the cards for the currently occupied part of
bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	327 // the old generation and clear the cards for the
0 a61af66fc99e Initial load duke parents: diff changeset	328 // unoccupied part of the generation (if any, making use
a61af66fc99e Initial load duke parents: diff changeset	329 // of that generation's prev_used_region to determine that
a61af66fc99e Initial load duke parents: diff changeset	330 // region). No need to do anything for the youngest
a61af66fc99e Initial load duke parents: diff changeset	331 // generation. Also see note#20040107.ysr above.
12033 bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	332 MemRegion used_mr = old_gen->used_region();
bd902affe102 8023021: Unnecessary clearing of the card table introduced by the fix for JDK-8023013 brutisso parents: 12030 diff changeset	333 MemRegion to_be_cleared_mr = old_gen->prev_used_region().minus(used_mr);
12030 330dfb0476f4 8022800: Use specific generations rather than generation iteration brutisso parents: 10271 diff changeset	334 if (!to_be_cleared_mr.is_empty()) {
330dfb0476f4 8022800: Use specific generations rather than generation iteration brutisso parents: 10271 diff changeset	335 clear(to_be_cleared_mr);
0 a61af66fc99e Initial load duke parents: diff changeset	336 }
12030 330dfb0476f4 8022800: Use specific generations rather than generation iteration brutisso parents: 10271 diff changeset	337 invalidate(used_mr);
0 a61af66fc99e Initial load duke parents: diff changeset	338 }
a61af66fc99e Initial load duke parents: diff changeset	339
a61af66fc99e Initial load duke parents: diff changeset	340
a61af66fc99e Initial load duke parents: diff changeset	341 class VerifyCleanCardClosure: public OopClosure {
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	342 private:
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	343 HeapWord* _boundary;
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	344 HeapWord* _begin;
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	345 HeapWord* _end;
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	346 protected:
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	347 template <class T> void do_oop_work(T* p) {
0 a61af66fc99e Initial load duke parents: diff changeset	348 HeapWord* jp = (HeapWord*)p;
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	349 assert(jp >= _begin && jp < _end,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	350 err_msg("Error: jp " PTR_FORMAT " should be within "
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	351 "[_begin, _end) = [" PTR_FORMAT "," PTR_FORMAT ")",
8668 3c9db54c2660 8008081: Print outs do not have matching arguments mikael parents: 8001 diff changeset	352 jp, _begin, _end));
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	353 oop obj = oopDesc::load_decode_heap_oop(p);
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	354 guarantee(obj == NULL \|\| (HeapWord*)obj >= _boundary,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	355 err_msg("pointer " PTR_FORMAT " at " PTR_FORMAT " on "
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	356 "clean card crosses boundary" PTR_FORMAT,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	357 (HeapWord*)obj, jp, _boundary));
0 a61af66fc99e Initial load duke parents: diff changeset	358 }
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	359
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	360 public:
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	361 VerifyCleanCardClosure(HeapWord* b, HeapWord* begin, HeapWord* end) :
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	362 _boundary(b), _begin(begin), _end(end) {
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	363 assert(b <= begin,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	364 err_msg("Error: boundary " PTR_FORMAT " should be at or below begin " PTR_FORMAT,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	365 b, begin));
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	366 assert(begin <= end,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	367 err_msg("Error: begin " PTR_FORMAT " should be strictly below end " PTR_FORMAT,
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	368 begin, end));
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	369 }
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	370
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	371 virtual void do_oop(oop* p) { VerifyCleanCardClosure::do_oop_work(p); }
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	372 virtual void do_oop(narrowOop* p) { VerifyCleanCardClosure::do_oop_work(p); }
0 a61af66fc99e Initial load duke parents: diff changeset	373 };
a61af66fc99e Initial load duke parents: diff changeset	374
a61af66fc99e Initial load duke parents: diff changeset	375 class VerifyCTSpaceClosure: public SpaceClosure {
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	376 private:
0 a61af66fc99e Initial load duke parents: diff changeset	377 CardTableRS* _ct;
a61af66fc99e Initial load duke parents: diff changeset	378 HeapWord* _boundary;
a61af66fc99e Initial load duke parents: diff changeset	379 public:
a61af66fc99e Initial load duke parents: diff changeset	380 VerifyCTSpaceClosure(CardTableRS* ct, HeapWord* boundary) :
a61af66fc99e Initial load duke parents: diff changeset	381 _ct(ct), _boundary(boundary) {}
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	382 virtual void do_space(Space* s) { _ct->verify_space(s, _boundary); }
0 a61af66fc99e Initial load duke parents: diff changeset	383 };
a61af66fc99e Initial load duke parents: diff changeset	384
a61af66fc99e Initial load duke parents: diff changeset	385 class VerifyCTGenClosure: public GenCollectedHeap::GenClosure {
a61af66fc99e Initial load duke parents: diff changeset	386 CardTableRS* _ct;
a61af66fc99e Initial load duke parents: diff changeset	387 public:
a61af66fc99e Initial load duke parents: diff changeset	388 VerifyCTGenClosure(CardTableRS* ct) : _ct(ct) {}
a61af66fc99e Initial load duke parents: diff changeset	389 void do_generation(Generation* gen) {
a61af66fc99e Initial load duke parents: diff changeset	390 // Skip the youngest generation.
a61af66fc99e Initial load duke parents: diff changeset	391 if (gen->level() == 0) return;
a61af66fc99e Initial load duke parents: diff changeset	392 // Normally, we're interested in pointers to younger generations.
a61af66fc99e Initial load duke parents: diff changeset	393 VerifyCTSpaceClosure blk(_ct, gen->reserved().start());
a61af66fc99e Initial load duke parents: diff changeset	394 gen->space_iterate(&blk, true);
a61af66fc99e Initial load duke parents: diff changeset	395 }
a61af66fc99e Initial load duke parents: diff changeset	396 };
a61af66fc99e Initial load duke parents: diff changeset	397
a61af66fc99e Initial load duke parents: diff changeset	398 void CardTableRS::verify_space(Space* s, HeapWord* gen_boundary) {
a61af66fc99e Initial load duke parents: diff changeset	399 // We don't need to do young-gen spaces.
a61af66fc99e Initial load duke parents: diff changeset	400 if (s->end() <= gen_boundary) return;
a61af66fc99e Initial load duke parents: diff changeset	401 MemRegion used = s->used_region();
a61af66fc99e Initial load duke parents: diff changeset	402
a61af66fc99e Initial load duke parents: diff changeset	403 jbyte* cur_entry = byte_for(used.start());
a61af66fc99e Initial load duke parents: diff changeset	404 jbyte* limit = byte_after(used.last());
a61af66fc99e Initial load duke parents: diff changeset	405 while (cur_entry < limit) {
a61af66fc99e Initial load duke parents: diff changeset	406 if (*cur_entry == CardTableModRefBS::clean_card) {
a61af66fc99e Initial load duke parents: diff changeset	407 jbyte* first_dirty = cur_entry+1;
a61af66fc99e Initial load duke parents: diff changeset	408 while (first_dirty < limit &&
a61af66fc99e Initial load duke parents: diff changeset	409 *first_dirty == CardTableModRefBS::clean_card) {
a61af66fc99e Initial load duke parents: diff changeset	410 first_dirty++;
a61af66fc99e Initial load duke parents: diff changeset	411 }
a61af66fc99e Initial load duke parents: diff changeset	412 // If the first object is a regular object, and it has a
a61af66fc99e Initial load duke parents: diff changeset	413 // young-to-old field, that would mark the previous card.
a61af66fc99e Initial load duke parents: diff changeset	414 HeapWord* boundary = addr_for(cur_entry);
a61af66fc99e Initial load duke parents: diff changeset	415 HeapWord* end = (first_dirty >= limit) ? used.end() : addr_for(first_dirty);
a61af66fc99e Initial load duke parents: diff changeset	416 HeapWord* boundary_block = s->block_start(boundary);
a61af66fc99e Initial load duke parents: diff changeset	417 HeapWord* begin = boundary; // Until proven otherwise.
a61af66fc99e Initial load duke parents: diff changeset	418 HeapWord* start_block = boundary_block; // Until proven otherwise.
a61af66fc99e Initial load duke parents: diff changeset	419 if (boundary_block < boundary) {
a61af66fc99e Initial load duke parents: diff changeset	420 if (s->block_is_obj(boundary_block) && s->obj_is_alive(boundary_block)) {
a61af66fc99e Initial load duke parents: diff changeset	421 oop boundary_obj = oop(boundary_block);
a61af66fc99e Initial load duke parents: diff changeset	422 if (!boundary_obj->is_objArray() &&
a61af66fc99e Initial load duke parents: diff changeset	423 !boundary_obj->is_typeArray()) {
a61af66fc99e Initial load duke parents: diff changeset	424 guarantee(cur_entry > byte_for(used.start()),
a61af66fc99e Initial load duke parents: diff changeset	425 "else boundary would be boundary_block");
a61af66fc99e Initial load duke parents: diff changeset	426 if (*byte_for(boundary_block) != CardTableModRefBS::clean_card) {
a61af66fc99e Initial load duke parents: diff changeset	427 begin = boundary_block + s->block_size(boundary_block);
a61af66fc99e Initial load duke parents: diff changeset	428 start_block = begin;
a61af66fc99e Initial load duke parents: diff changeset	429 }
a61af66fc99e Initial load duke parents: diff changeset	430 }
a61af66fc99e Initial load duke parents: diff changeset	431 }
a61af66fc99e Initial load duke parents: diff changeset	432 }
a61af66fc99e Initial load duke parents: diff changeset	433 // Now traverse objects until end.
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	434 if (begin < end) {
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	435 MemRegion mr(begin, end);
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	436 VerifyCleanCardClosure verify_blk(gen_boundary, begin, end);
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	437 for (HeapWord* cur = start_block; cur < end; cur += s->block_size(cur)) {
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	438 if (s->block_is_obj(cur) && s->obj_is_alive(cur)) {
6725 da91efe96a93 6964458: Reimplement class meta-data storage to use native memory coleenp parents: 5939 diff changeset	439 oop(cur)->oop_iterate_no_header(&verify_blk, mr);
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	440 }
0 a61af66fc99e Initial load duke parents: diff changeset	441 }
a61af66fc99e Initial load duke parents: diff changeset	442 }
a61af66fc99e Initial load duke parents: diff changeset	443 cur_entry = first_dirty;
a61af66fc99e Initial load duke parents: diff changeset	444 } else {
a61af66fc99e Initial load duke parents: diff changeset	445 // We'd normally expect that cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	446 // is a transient value, that cannot be in the card table
a61af66fc99e Initial load duke parents: diff changeset	447 // except during GC, and thus assert that:
a61af66fc99e Initial load duke parents: diff changeset	448 // guarantee(*cur_entry != cur_youngergen_and_prev_nonclean_card,
a61af66fc99e Initial load duke parents: diff changeset	449 // "Illegal CT value");
a61af66fc99e Initial load duke parents: diff changeset	450 // That however, need not hold, as will become clear in the
a61af66fc99e Initial load duke parents: diff changeset	451 // following...
a61af66fc99e Initial load duke parents: diff changeset	452
a61af66fc99e Initial load duke parents: diff changeset	453 // We'd normally expect that if we are in the parallel case,
a61af66fc99e Initial load duke parents: diff changeset	454 // we can't have left a prev value (which would be different
a61af66fc99e Initial load duke parents: diff changeset	455 // from the current value) in the card table, and so we'd like to
a61af66fc99e Initial load duke parents: diff changeset	456 // assert that:
a61af66fc99e Initial load duke parents: diff changeset	457 // guarantee(cur_youngergen_card_val() == youngergen_card
a61af66fc99e Initial load duke parents: diff changeset	458 // \|\| !is_prev_youngergen_card_val(*cur_entry),
a61af66fc99e Initial load duke parents: diff changeset	459 // "Illegal CT value");
a61af66fc99e Initial load duke parents: diff changeset	460 // That, however, may not hold occasionally, because of
a61af66fc99e Initial load duke parents: diff changeset	461 // CMS or MSC in the old gen. To wit, consider the
a61af66fc99e Initial load duke parents: diff changeset	462 // following two simple illustrative scenarios:
a61af66fc99e Initial load duke parents: diff changeset	463 // (a) CMS: Consider the case where a large object L
a61af66fc99e Initial load duke parents: diff changeset	464 // spanning several cards is allocated in the old
a61af66fc99e Initial load duke parents: diff changeset	465 // gen, and has a young gen reference stored in it, dirtying
a61af66fc99e Initial load duke parents: diff changeset	466 // some interior cards. A young collection scans the card,
a61af66fc99e Initial load duke parents: diff changeset	467 // finds a young ref and installs a youngergenP_n value.
a61af66fc99e Initial load duke parents: diff changeset	468 // L then goes dead. Now a CMS collection starts,
a61af66fc99e Initial load duke parents: diff changeset	469 // finds L dead and sweeps it up. Assume that L is
a61af66fc99e Initial load duke parents: diff changeset	470 // abutting _unallocated_blk, so _unallocated_blk is
a61af66fc99e Initial load duke parents: diff changeset	471 // adjusted down to (below) L. Assume further that
a61af66fc99e Initial load duke parents: diff changeset	472 // no young collection intervenes during this CMS cycle.
a61af66fc99e Initial load duke parents: diff changeset	473 // The next young gen cycle will not get to look at this
a61af66fc99e Initial load duke parents: diff changeset	474 // youngergenP_n card since it lies in the unoccupied
a61af66fc99e Initial load duke parents: diff changeset	475 // part of the space.
a61af66fc99e Initial load duke parents: diff changeset	476 // Some young collections later the blocks on this
a61af66fc99e Initial load duke parents: diff changeset	477 // card can be re-allocated either due to direct allocation
a61af66fc99e Initial load duke parents: diff changeset	478 // or due to absorbing promotions. At this time, the
a61af66fc99e Initial load duke parents: diff changeset	479 // before-gc verification will fail the above assert.
a61af66fc99e Initial load duke parents: diff changeset	480 // (b) MSC: In this case, an object L with a young reference
a61af66fc99e Initial load duke parents: diff changeset	481 // is on a card that (therefore) holds a youngergen_n value.
a61af66fc99e Initial load duke parents: diff changeset	482 // Suppose also that L lies towards the end of the used
a61af66fc99e Initial load duke parents: diff changeset	483 // the used space before GC. An MSC collection
a61af66fc99e Initial load duke parents: diff changeset	484 // occurs that compacts to such an extent that this
a61af66fc99e Initial load duke parents: diff changeset	485 // card is no longer in the occupied part of the space.
a61af66fc99e Initial load duke parents: diff changeset	486 // Since current code in MSC does not always clear cards
a61af66fc99e Initial load duke parents: diff changeset	487 // in the unused part of old gen, this stale youngergen_n
a61af66fc99e Initial load duke parents: diff changeset	488 // value is left behind and can later be covered by
a61af66fc99e Initial load duke parents: diff changeset	489 // an object when promotion or direct allocation
a61af66fc99e Initial load duke parents: diff changeset	490 // re-allocates that part of the heap.
a61af66fc99e Initial load duke parents: diff changeset	491 //
a61af66fc99e Initial load duke parents: diff changeset	492 // Fortunately, the presence of such stale card values is
a61af66fc99e Initial load duke parents: diff changeset	493 // "only" a minor annoyance in that subsequent young collections
a61af66fc99e Initial load duke parents: diff changeset	494 // might needlessly scan such cards, but would still never corrupt
a61af66fc99e Initial load duke parents: diff changeset	495 // the heap as a result. However, it's likely not to be a significant
a61af66fc99e Initial load duke parents: diff changeset	496 // performance inhibitor in practice. For instance,
a61af66fc99e Initial load duke parents: diff changeset	497 // some recent measurements with unoccupied cards eagerly cleared
a61af66fc99e Initial load duke parents: diff changeset	498 // out to maintain this invariant, showed next to no
a61af66fc99e Initial load duke parents: diff changeset	499 // change in young collection times; of course one can construct
a61af66fc99e Initial load duke parents: diff changeset	500 // degenerate examples where the cost can be significant.)
a61af66fc99e Initial load duke parents: diff changeset	501 // Note, in particular, that if the "stale" card is modified
a61af66fc99e Initial load duke parents: diff changeset	502 // after re-allocation, it would be dirty, not "stale". Thus,
a61af66fc99e Initial load duke parents: diff changeset	503 // we can never have a younger ref in such a card and it is
a61af66fc99e Initial load duke parents: diff changeset	504 // safe not to scan that card in any collection. [As we see
a61af66fc99e Initial load duke parents: diff changeset	505 // below, we do some unnecessary scanning
a61af66fc99e Initial load duke parents: diff changeset	506 // in some cases in the current parallel scanning algorithm.]
a61af66fc99e Initial load duke parents: diff changeset	507 //
a61af66fc99e Initial load duke parents: diff changeset	508 // The main point below is that the parallel card scanning code
a61af66fc99e Initial load duke parents: diff changeset	509 // deals correctly with these stale card values. There are two main
a61af66fc99e Initial load duke parents: diff changeset	510 // cases to consider where we have a stale "younger gen" value and a
a61af66fc99e Initial load duke parents: diff changeset	511 // "derivative" case to consider, where we have a stale
a61af66fc99e Initial load duke parents: diff changeset	512 // "cur_younger_gen_and_prev_non_clean" value, as will become
a61af66fc99e Initial load duke parents: diff changeset	513 // apparent in the case analysis below.
a61af66fc99e Initial load duke parents: diff changeset	514 // o Case 1. If the stale value corresponds to a younger_gen_n
a61af66fc99e Initial load duke parents: diff changeset	515 // value other than the cur_younger_gen value then the code
a61af66fc99e Initial load duke parents: diff changeset	516 // treats this as being tantamount to a prev_younger_gen
a61af66fc99e Initial load duke parents: diff changeset	517 // card. This means that the card may be unnecessarily scanned.
a61af66fc99e Initial load duke parents: diff changeset	518 // There are two sub-cases to consider:
a61af66fc99e Initial load duke parents: diff changeset	519 // o Case 1a. Let us say that the card is in the occupied part
a61af66fc99e Initial load duke parents: diff changeset	520 // of the generation at the time the collection begins. In
a61af66fc99e Initial load duke parents: diff changeset	521 // that case the card will be either cleared when it is scanned
a61af66fc99e Initial load duke parents: diff changeset	522 // for young pointers, or will be set to cur_younger_gen as a
a61af66fc99e Initial load duke parents: diff changeset	523 // result of promotion. (We have elided the normal case where
a61af66fc99e Initial load duke parents: diff changeset	524 // the scanning thread and the promoting thread interleave
a61af66fc99e Initial load duke parents: diff changeset	525 // possibly resulting in a transient
a61af66fc99e Initial load duke parents: diff changeset	526 // cur_younger_gen_and_prev_non_clean value before settling
a61af66fc99e Initial load duke parents: diff changeset	527 // to cur_younger_gen. [End Case 1a.]
a61af66fc99e Initial load duke parents: diff changeset	528 // o Case 1b. Consider now the case when the card is in the unoccupied
a61af66fc99e Initial load duke parents: diff changeset	529 // part of the space which becomes occupied because of promotions
a61af66fc99e Initial load duke parents: diff changeset	530 // into it during the current young GC. In this case the card
a61af66fc99e Initial load duke parents: diff changeset	531 // will never be scanned for young references. The current
a61af66fc99e Initial load duke parents: diff changeset	532 // code will set the card value to either
a61af66fc99e Initial load duke parents: diff changeset	533 // cur_younger_gen_and_prev_non_clean or leave
a61af66fc99e Initial load duke parents: diff changeset	534 // it with its stale value -- because the promotions didn't
a61af66fc99e Initial load duke parents: diff changeset	535 // result in any younger refs on that card. Of these two
a61af66fc99e Initial load duke parents: diff changeset	536 // cases, the latter will be covered in Case 1a during
a61af66fc99e Initial load duke parents: diff changeset	537 // a subsequent scan. To deal with the former case, we need
a61af66fc99e Initial load duke parents: diff changeset	538 // to further consider how we deal with a stale value of
a61af66fc99e Initial load duke parents: diff changeset	539 // cur_younger_gen_and_prev_non_clean in our case analysis
a61af66fc99e Initial load duke parents: diff changeset	540 // below. This we do in Case 3 below. [End Case 1b]
a61af66fc99e Initial load duke parents: diff changeset	541 // [End Case 1]
a61af66fc99e Initial load duke parents: diff changeset	542 // o Case 2. If the stale value corresponds to cur_younger_gen being
a61af66fc99e Initial load duke parents: diff changeset	543 // a value not necessarily written by a current promotion, the
a61af66fc99e Initial load duke parents: diff changeset	544 // card will not be scanned by the younger refs scanning code.
a61af66fc99e Initial load duke parents: diff changeset	545 // (This is OK since as we argued above such cards cannot contain
a61af66fc99e Initial load duke parents: diff changeset	546 // any younger refs.) The result is that this value will be
a61af66fc99e Initial load duke parents: diff changeset	547 // treated as a prev_younger_gen value in a subsequent collection,
a61af66fc99e Initial load duke parents: diff changeset	548 // which is addressed in Case 1 above. [End Case 2]
a61af66fc99e Initial load duke parents: diff changeset	549 // o Case 3. We here consider the "derivative" case from Case 1b. above
a61af66fc99e Initial load duke parents: diff changeset	550 // because of which we may find a stale
a61af66fc99e Initial load duke parents: diff changeset	551 // cur_younger_gen_and_prev_non_clean card value in the table.
a61af66fc99e Initial load duke parents: diff changeset	552 // Once again, as in Case 1, we consider two subcases, depending
a61af66fc99e Initial load duke parents: diff changeset	553 // on whether the card lies in the occupied or unoccupied part
a61af66fc99e Initial load duke parents: diff changeset	554 // of the space at the start of the young collection.
a61af66fc99e Initial load duke parents: diff changeset	555 // o Case 3a. Let us say the card is in the occupied part of
a61af66fc99e Initial load duke parents: diff changeset	556 // the old gen at the start of the young collection. In that
a61af66fc99e Initial load duke parents: diff changeset	557 // case, the card will be scanned by the younger refs scanning
a61af66fc99e Initial load duke parents: diff changeset	558 // code which will set it to cur_younger_gen. In a subsequent
a61af66fc99e Initial load duke parents: diff changeset	559 // scan, the card will be considered again and get its final
a61af66fc99e Initial load duke parents: diff changeset	560 // correct value. [End Case 3a]
a61af66fc99e Initial load duke parents: diff changeset	561 // o Case 3b. Now consider the case where the card is in the
a61af66fc99e Initial load duke parents: diff changeset	562 // unoccupied part of the old gen, and is occupied as a result
a61af66fc99e Initial load duke parents: diff changeset	563 // of promotions during thus young gc. In that case,
a61af66fc99e Initial load duke parents: diff changeset	564 // the card will not be scanned for younger refs. The presence
a61af66fc99e Initial load duke parents: diff changeset	565 // of newly promoted objects on the card will then result in
a61af66fc99e Initial load duke parents: diff changeset	566 // its keeping the value cur_younger_gen_and_prev_non_clean
a61af66fc99e Initial load duke parents: diff changeset	567 // value, which we have dealt with in Case 3 here. [End Case 3b]
a61af66fc99e Initial load duke parents: diff changeset	568 // [End Case 3]
a61af66fc99e Initial load duke parents: diff changeset	569 //
a61af66fc99e Initial load duke parents: diff changeset	570 // (Please refer to the code in the helper class
a61af66fc99e Initial load duke parents: diff changeset	571 // ClearNonCleanCardWrapper and in CardTableModRefBS for details.)
a61af66fc99e Initial load duke parents: diff changeset	572 //
a61af66fc99e Initial load duke parents: diff changeset	573 // The informal arguments above can be tightened into a formal
a61af66fc99e Initial load duke parents: diff changeset	574 // correctness proof and it behooves us to write up such a proof,
a61af66fc99e Initial load duke parents: diff changeset	575 // or to use model checking to prove that there are no lingering
a61af66fc99e Initial load duke parents: diff changeset	576 // concerns.
a61af66fc99e Initial load duke parents: diff changeset	577 //
a61af66fc99e Initial load duke parents: diff changeset	578 // Clearly because of Case 3b one cannot bound the time for
a61af66fc99e Initial load duke parents: diff changeset	579 // which a card will retain what we have called a "stale" value.
a61af66fc99e Initial load duke parents: diff changeset	580 // However, one can obtain a Loose upper bound on the redundant
a61af66fc99e Initial load duke parents: diff changeset	581 // work as a result of such stale values. Note first that any
a61af66fc99e Initial load duke parents: diff changeset	582 // time a stale card lies in the occupied part of the space at
a61af66fc99e Initial load duke parents: diff changeset	583 // the start of the collection, it is scanned by younger refs
a61af66fc99e Initial load duke parents: diff changeset	584 // code and we can define a rank function on card values that
a61af66fc99e Initial load duke parents: diff changeset	585 // declines when this is so. Note also that when a card does not
a61af66fc99e Initial load duke parents: diff changeset	586 // lie in the occupied part of the space at the beginning of a
a61af66fc99e Initial load duke parents: diff changeset	587 // young collection, its rank can either decline or stay unchanged.
a61af66fc99e Initial load duke parents: diff changeset	588 // In this case, no extra work is done in terms of redundant
a61af66fc99e Initial load duke parents: diff changeset	589 // younger refs scanning of that card.
a61af66fc99e Initial load duke parents: diff changeset	590 // Then, the case analysis above reveals that, in the worst case,
a61af66fc99e Initial load duke parents: diff changeset	591 // any such stale card will be scanned unnecessarily at most twice.
a61af66fc99e Initial load duke parents: diff changeset	592 //
a61af66fc99e Initial load duke parents: diff changeset	593 // It is nonethelss advisable to try and get rid of some of this
a61af66fc99e Initial load duke parents: diff changeset	594 // redundant work in a subsequent (low priority) re-design of
a61af66fc99e Initial load duke parents: diff changeset	595 // the card-scanning code, if only to simplify the underlying
a61af66fc99e Initial load duke parents: diff changeset	596 // state machine analysis/proof. ysr 1/28/2002. XXX
a61af66fc99e Initial load duke parents: diff changeset	597 cur_entry++;
a61af66fc99e Initial load duke parents: diff changeset	598 }
a61af66fc99e Initial load duke parents: diff changeset	599 }
a61af66fc99e Initial load duke parents: diff changeset	600 }
a61af66fc99e Initial load duke parents: diff changeset	601
a61af66fc99e Initial load duke parents: diff changeset	602 void CardTableRS::verify() {
a61af66fc99e Initial load duke parents: diff changeset	603 // At present, we only know how to verify the card table RS for
a61af66fc99e Initial load duke parents: diff changeset	604 // generational heaps.
a61af66fc99e Initial load duke parents: diff changeset	605 VerifyCTGenClosure blk(this);
a61af66fc99e Initial load duke parents: diff changeset	606 CollectedHeap* ch = Universe::heap();
a61af66fc99e Initial load duke parents: diff changeset	607
a61af66fc99e Initial load duke parents: diff changeset	608 if (ch->kind() == CollectedHeap::GenCollectedHeap) {
a61af66fc99e Initial load duke parents: diff changeset	609 GenCollectedHeap::heap()->generation_iterate(&blk, false);
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	610 _ct_bs->verify();
0 a61af66fc99e Initial load duke parents: diff changeset	611 }
a61af66fc99e Initial load duke parents: diff changeset	612 }
a61af66fc99e Initial load duke parents: diff changeset	613
a61af66fc99e Initial load duke parents: diff changeset	614
6 73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	615 void CardTableRS::verify_aligned_region_empty(MemRegion mr) {
0 a61af66fc99e Initial load duke parents: diff changeset	616 if (!mr.is_empty()) {
a61af66fc99e Initial load duke parents: diff changeset	617 jbyte* cur_entry = byte_for(mr.start());
a61af66fc99e Initial load duke parents: diff changeset	618 jbyte* limit = byte_after(mr.last());
6 73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	619 // The region mr may not start on a card boundary so
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	620 // the first card may reflect a write to the space
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	621 // just prior to mr.
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	622 if (!is_aligned(mr.start())) {
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	623 cur_entry++;
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	624 }
0 a61af66fc99e Initial load duke parents: diff changeset	625 for (;cur_entry < limit; cur_entry++) {
a61af66fc99e Initial load duke parents: diff changeset	626 guarantee(*cur_entry == CardTableModRefBS::clean_card,
a61af66fc99e Initial load duke parents: diff changeset	627 "Unexpected dirty card found");
a61af66fc99e Initial load duke parents: diff changeset	628 }
a61af66fc99e Initial load duke parents: diff changeset	629 }
a61af66fc99e Initial load duke parents: diff changeset	630 }

Mercurial > hg > truffle

annotate src/share/vm/memory/cardTableRS.cpp @ 12033:bd902affe102