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

annotate src/share/vm/memory/cardTableRS.cpp @ 5939:c7a555a9449a

7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning Summary: Check clean words instead of clean bytes Reviewed-by: jcoomes, jmasa, jwilhelm, ysr Contributed-by: alexey.ragozin@gmail.com

author	brutisso
date	Wed, 14 Mar 2012 12:49:27 +0100
parents	bca17e38de00
children	da91efe96a93

rev	line source
0 a61af66fc99e Initial load duke parents: diff changeset	1 /*
5939 c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	2 * Copyright (c) 2001, 2012, 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"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	34 #ifndef SERIALGC
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	35 #include "gc_implementation/g1/concurrentMark.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	36 #include "gc_implementation/g1/g1SATBCardTableModRefBS.hpp"
f95d63e2154a 6989984: Use standard include model for Hospot stefank parents: 1552 diff changeset	37 #endif
0 a61af66fc99e Initial load duke parents: diff changeset	38
a61af66fc99e Initial load duke parents: diff changeset	39 CardTableRS::CardTableRS(MemRegion whole_heap,
a61af66fc99e Initial load duke parents: diff changeset	40 int max_covered_regions) :
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	41 GenRemSet(),
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	42 _cur_youngergen_card_val(youngergenP1_card),
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	43 _regions_to_iterate(max_covered_regions - 1)
0 a61af66fc99e Initial load duke parents: diff changeset	44 {
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	45 #ifndef SERIALGC
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	46 if (UseG1GC) {
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	47 _ct_bs = new G1SATBCardTableLoggingModRefBS(whole_heap,
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	48 max_covered_regions);
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	49 } else {
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	50 _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	51 }
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	52 #else
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	53 _ct_bs = new CardTableModRefBSForCTRS(whole_heap, max_covered_regions);
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	54 #endif
37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	55 set_bs(_ct_bs);
0 a61af66fc99e Initial load duke parents: diff changeset	56 _last_cur_val_in_gen = new jbyte[GenCollectedHeap::max_gens + 1];
a61af66fc99e Initial load duke parents: diff changeset	57 if (_last_cur_val_in_gen == NULL) {
a61af66fc99e Initial load duke parents: diff changeset	58 vm_exit_during_initialization("Could not last_cur_val_in_gen array.");
a61af66fc99e Initial load duke parents: diff changeset	59 }
a61af66fc99e Initial load duke parents: diff changeset	60 for (int i = 0; i < GenCollectedHeap::max_gens + 1; i++) {
a61af66fc99e Initial load duke parents: diff changeset	61 _last_cur_val_in_gen[i] = clean_card_val();
a61af66fc99e Initial load duke parents: diff changeset	62 }
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	63 _ct_bs->set_CTRS(this);
0 a61af66fc99e Initial load duke parents: diff changeset	64 }
a61af66fc99e Initial load duke parents: diff changeset	65
a61af66fc99e Initial load duke parents: diff changeset	66 void CardTableRS::resize_covered_region(MemRegion new_region) {
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	67 _ct_bs->resize_covered_region(new_region);
0 a61af66fc99e Initial load duke parents: diff changeset	68 }
a61af66fc99e Initial load duke parents: diff changeset	69
a61af66fc99e Initial load duke parents: diff changeset	70 jbyte CardTableRS::find_unused_youngergenP_card_value() {
a61af66fc99e Initial load duke parents: diff changeset	71 for (jbyte v = youngergenP1_card;
a61af66fc99e Initial load duke parents: diff changeset	72 v < cur_youngergen_and_prev_nonclean_card;
a61af66fc99e Initial load duke parents: diff changeset	73 v++) {
a61af66fc99e Initial load duke parents: diff changeset	74 bool seen = false;
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	75 for (int g = 0; g < _regions_to_iterate; g++) {
0 a61af66fc99e Initial load duke parents: diff changeset	76 if (_last_cur_val_in_gen[g] == v) {
a61af66fc99e Initial load duke parents: diff changeset	77 seen = true;
a61af66fc99e Initial load duke parents: diff changeset	78 break;
a61af66fc99e Initial load duke parents: diff changeset	79 }
a61af66fc99e Initial load duke parents: diff changeset	80 }
a61af66fc99e Initial load duke parents: diff changeset	81 if (!seen) return v;
a61af66fc99e Initial load duke parents: diff changeset	82 }
a61af66fc99e Initial load duke parents: diff changeset	83 ShouldNotReachHere();
a61af66fc99e Initial load duke parents: diff changeset	84 return 0;
a61af66fc99e Initial load duke parents: diff changeset	85 }
a61af66fc99e Initial load duke parents: diff changeset	86
a61af66fc99e Initial load duke parents: diff changeset	87 void CardTableRS::prepare_for_younger_refs_iterate(bool parallel) {
a61af66fc99e Initial load duke parents: diff changeset	88 // Parallel or sequential, we must always set the prev to equal the
a61af66fc99e Initial load duke parents: diff changeset	89 // last one written.
a61af66fc99e Initial load duke parents: diff changeset	90 if (parallel) {
a61af66fc99e Initial load duke parents: diff changeset	91 // Find a parallel value to be used next.
a61af66fc99e Initial load duke parents: diff changeset	92 jbyte next_val = find_unused_youngergenP_card_value();
a61af66fc99e Initial load duke parents: diff changeset	93 set_cur_youngergen_card_val(next_val);
a61af66fc99e Initial load duke parents: diff changeset	94
a61af66fc99e Initial load duke parents: diff changeset	95 } else {
a61af66fc99e Initial load duke parents: diff changeset	96 // In an sequential traversal we will always write youngergen, so that
a61af66fc99e Initial load duke parents: diff changeset	97 // the inline barrier is correct.
a61af66fc99e Initial load duke parents: diff changeset	98 set_cur_youngergen_card_val(youngergen_card);
a61af66fc99e Initial load duke parents: diff changeset	99 }
a61af66fc99e Initial load duke parents: diff changeset	100 }
a61af66fc99e Initial load duke parents: diff changeset	101
a61af66fc99e Initial load duke parents: diff changeset	102 void CardTableRS::younger_refs_iterate(Generation* g,
a61af66fc99e Initial load duke parents: diff changeset	103 OopsInGenClosure* blk) {
a61af66fc99e Initial load duke parents: diff changeset	104 _last_cur_val_in_gen[g->level()+1] = cur_youngergen_card_val();
a61af66fc99e Initial load duke parents: diff changeset	105 g->younger_refs_iterate(blk);
a61af66fc99e Initial load duke parents: diff changeset	106 }
a61af66fc99e Initial load duke parents: diff changeset	107
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	108 inline bool ClearNoncleanCardWrapper::clear_card(jbyte* entry) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	109 if (_is_par) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	110 return clear_card_parallel(entry);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	111 } else {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	112 return clear_card_serial(entry);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	113 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	114 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	115
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	116 inline bool ClearNoncleanCardWrapper::clear_card_parallel(jbyte* entry) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	117 while (true) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	118 // 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	119 jbyte entry_val = *entry;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	120 assert(entry_val != CardTableRS::clean_card_val(),
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	121 "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	122 "be the only place they get cleaned.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	123 if (CardTableRS::card_is_dirty_wrt_gen_iter(entry_val)
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	124 \|\| _ct->is_prev_youngergen_card_val(entry_val)) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	125 jbyte res =
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	126 Atomic::cmpxchg(CardTableRS::clean_card_val(), entry, entry_val);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	127 if (res == entry_val) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	128 break;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	129 } else {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	130 assert(res == CardTableRS::cur_youngergen_and_prev_nonclean_card,
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	131 "The CAS above should only fail if another thread did "
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	132 "a GC write barrier.");
0 a61af66fc99e Initial load duke parents: diff changeset	133 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	134 } else if (entry_val ==
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	135 CardTableRS::cur_youngergen_and_prev_nonclean_card) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	136 // Parallelism shouldn't matter in this case. Only the thread
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	137 // assigned to scan the card should change this value.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	138 *entry = _ct->cur_youngergen_card_val();
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	139 break;
0 a61af66fc99e Initial load duke parents: diff changeset	140 } else {
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	141 assert(entry_val == _ct->cur_youngergen_card_val(),
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	142 "Should be the only possibility.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	143 // In this case, the card was clean before, and become
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	144 // cur_youngergen only because of processing of a promoted object.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	145 // We don't have to look at the card.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	146 return false;
0 a61af66fc99e Initial load duke parents: diff changeset	147 }
a61af66fc99e Initial load duke parents: diff changeset	148 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	149 return true;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	150 }
0 a61af66fc99e Initial load duke parents: diff changeset	151
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	152
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	153 inline bool ClearNoncleanCardWrapper::clear_card_serial(jbyte* entry) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	154 jbyte entry_val = *entry;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	155 assert(entry_val != CardTableRS::clean_card_val(),
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	156 "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	157 "be the only place they get cleaned.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	158 assert(entry_val != CardTableRS::cur_youngergen_and_prev_nonclean_card,
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	159 "This should be possible in the sequential case.");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	160 *entry = CardTableRS::clean_card_val();
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 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	163
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	164 ClearNoncleanCardWrapper::ClearNoncleanCardWrapper(
3357 fc2b798ab316 6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests ysr parents: 3293 diff changeset	165 DirtyCardToOopClosure* dirty_card_closure, CardTableRS* ct) :
0 a61af66fc99e Initial load duke parents: diff changeset	166 _dirty_card_closure(dirty_card_closure), _ct(ct) {
4095 bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	167 // Cannot yet substitute active_workers for n_par_threads
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	168 // 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	169 // setting n_par_threads to 0.
0 a61af66fc99e Initial load duke parents: diff changeset	170 _is_par = (SharedHeap::heap()->n_par_threads() > 0);
4095 bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	171 assert(!_is_par \|\|
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	172 (SharedHeap::heap()->n_par_threads() ==
bca17e38de00 6593758: RFE: Enhance GC ergonomics to dynamically choose ParallelGCThreads jmasa parents: 3357 diff changeset	173 SharedHeap::heap()->workers()->active_workers()), "Mismatch");
3287 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
5939 c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	176 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	177 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	178 }
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	179
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	180 void ClearNoncleanCardWrapper::do_MemRegion(MemRegion mr) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	181 assert(mr.word_size() > 0, "Error");
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	182 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	183 // mr.end() may not necessarily be card aligned.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	184 jbyte* cur_entry = _ct->byte_for(mr.last());
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	185 const jbyte* limit = _ct->byte_for(mr.start());
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	186 HeapWord* end_of_non_clean = mr.end();
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	187 HeapWord* start_of_non_clean = end_of_non_clean;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	188 while (cur_entry >= limit) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	189 HeapWord* cur_hw = _ct->addr_for(cur_entry);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	190 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	191 // Continue the dirty range by opening the
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	192 // dirty window one card to the left.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	193 start_of_non_clean = cur_hw;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	194 } else {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	195 // We hit a "clean" card; process any non-empty
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	196 // "dirty" range accumulated so far.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	197 if (start_of_non_clean < end_of_non_clean) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	198 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	199 _dirty_card_closure->do_MemRegion(mrd);
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	200 }
5939 c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	201
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	202 // 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	203 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	204 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	205 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	206 cur_row -= BytesPerWord;
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	207 }
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	208 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	209 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	210 }
c7a555a9449a 7068625: Testing 8 bytes of card table entries at a time speeds up card-scanning brutisso parents: 4095 diff changeset	211
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	212 // Reset the dirty window, while continuing to look
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	213 // for the next dirty card that will start a
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	214 // new dirty window.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	215 end_of_non_clean = cur_hw;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	216 start_of_non_clean = cur_hw;
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	217 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	218 // Note that "cur_entry" leads "start_of_non_clean" in
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	219 // its leftward excursion after this point
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	220 // 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	221 // 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	222 // for "mr".
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	223 cur_entry--;
0 a61af66fc99e Initial load duke parents: diff changeset	224 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	225 // 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	226 // been left with a dirty window, co-initial with "mr",
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	227 // which we now process.
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	228 if (start_of_non_clean < end_of_non_clean) {
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	229 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	230 _dirty_card_closure->do_MemRegion(mrd);
0 a61af66fc99e Initial load duke parents: diff changeset	231 }
3287 c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	232 }
c48ad6ab8bdf 7037276: Unnecessary double traversal of dirty card windows ysr parents: 3256 diff changeset	233
0 a61af66fc99e Initial load duke parents: diff changeset	234 // clean (by dirty->clean before) ==> cur_younger_gen
a61af66fc99e Initial load duke parents: diff changeset	235 // dirty ==> cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	236 // precleaned ==> cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	237 // prev-younger-gen ==> cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	238 // cur-younger-gen ==> cur_younger_gen
a61af66fc99e Initial load duke parents: diff changeset	239 // 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	240 void CardTableRS::write_ref_field_gc_par(void* field, oop new_val) {
0 a61af66fc99e Initial load duke parents: diff changeset	241 jbyte* entry = ct_bs()->byte_for(field);
a61af66fc99e Initial load duke parents: diff changeset	242 do {
a61af66fc99e Initial load duke parents: diff changeset	243 jbyte entry_val = *entry;
a61af66fc99e Initial load duke parents: diff changeset	244 // We put this first because it's probably the most common case.
a61af66fc99e Initial load duke parents: diff changeset	245 if (entry_val == clean_card_val()) {
a61af66fc99e Initial load duke parents: diff changeset	246 // No threat of contention with cleaning threads.
a61af66fc99e Initial load duke parents: diff changeset	247 *entry = cur_youngergen_card_val();
a61af66fc99e Initial load duke parents: diff changeset	248 return;
a61af66fc99e Initial load duke parents: diff changeset	249 } else if (card_is_dirty_wrt_gen_iter(entry_val)
a61af66fc99e Initial load duke parents: diff changeset	250 \|\| is_prev_youngergen_card_val(entry_val)) {
a61af66fc99e Initial load duke parents: diff changeset	251 // Mark it as both cur and prev youngergen; card cleaning thread will
a61af66fc99e Initial load duke parents: diff changeset	252 // eventually remove the previous stuff.
a61af66fc99e Initial load duke parents: diff changeset	253 jbyte new_val = cur_youngergen_and_prev_nonclean_card;
a61af66fc99e Initial load duke parents: diff changeset	254 jbyte res = Atomic::cmpxchg(new_val, entry, entry_val);
a61af66fc99e Initial load duke parents: diff changeset	255 // Did the CAS succeed?
a61af66fc99e Initial load duke parents: diff changeset	256 if (res == entry_val) return;
a61af66fc99e Initial load duke parents: diff changeset	257 // Otherwise, retry, to see the new value.
a61af66fc99e Initial load duke parents: diff changeset	258 continue;
a61af66fc99e Initial load duke parents: diff changeset	259 } else {
a61af66fc99e Initial load duke parents: diff changeset	260 assert(entry_val == cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	261 \|\| entry_val == cur_youngergen_card_val(),
a61af66fc99e Initial load duke parents: diff changeset	262 "should be only possibilities.");
a61af66fc99e Initial load duke parents: diff changeset	263 return;
a61af66fc99e Initial load duke parents: diff changeset	264 }
a61af66fc99e Initial load duke parents: diff changeset	265 } while (true);
a61af66fc99e Initial load duke parents: diff changeset	266 }
a61af66fc99e Initial load duke parents: diff changeset	267
a61af66fc99e Initial load duke parents: diff changeset	268 void CardTableRS::younger_refs_in_space_iterate(Space* sp,
a61af66fc99e Initial load duke parents: diff changeset	269 OopsInGenClosure* cl) {
3293 1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	270 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	271 #ifdef ASSERT
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	272 // 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	273 // CMS+ParNew until related bug is fixed.
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	274 MemRegion ur = sp->used_region();
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	275 assert(ur.contains(urasm) \|\| (UseConcMarkSweepGC && UseParNewGC),
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	276 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	277 "[" 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	278 "[" PTR_FORMAT ", " PTR_FORMAT ")",
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	279 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	280 // 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	281 if (!ur.contains(urasm)) {
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	282 assert(UseConcMarkSweepGC && UseParNewGC, "Tautology: see assert above");
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	283 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	284 "[" 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	285 "[" PTR_FORMAT ", " PTR_FORMAT ")",
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	286 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	287 MemRegion ur2 = sp->used_region();
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	288 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	289 if (!ur.equals(ur2)) {
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	290 warning("CMS+ParNew: Flickering used_region()!!");
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	291 }
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	292 if (!urasm.equals(urasm2)) {
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	293 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	294 }
3357 fc2b798ab316 6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests ysr parents: 3293 diff changeset	295 ShouldNotReachHere();
3293 1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	296 }
1f4413413144 7039089: G1: changeset for 7037276 broke heap verification, and related cleanups ysr parents: 3287 diff changeset	297 #endif
3357 fc2b798ab316 6883834: ParNew: assert(!_g->to()->is_in_reserved(obj),"Scanning field twice?") with LargeObjects tests ysr parents: 3293 diff changeset	298 _ct_bs->non_clean_card_iterate_possibly_parallel(sp, urasm, cl, this);
0 a61af66fc99e Initial load duke parents: diff changeset	299 }
a61af66fc99e Initial load duke parents: diff changeset	300
a61af66fc99e Initial load duke parents: diff changeset	301 void CardTableRS::clear_into_younger(Generation* gen, bool clear_perm) {
a61af66fc99e Initial load duke parents: diff changeset	302 GenCollectedHeap* gch = GenCollectedHeap::heap();
a61af66fc99e Initial load duke parents: diff changeset	303 // Generations younger than gen have been evacuated. We can clear
a61af66fc99e Initial load duke parents: diff changeset	304 // card table entries for gen (we know that it has no pointers
a61af66fc99e Initial load duke parents: diff changeset	305 // to younger gens) and for those below. The card tables for
a61af66fc99e Initial load duke parents: diff changeset	306 // the youngest gen need never be cleared, and those for perm gen
a61af66fc99e Initial load duke parents: diff changeset	307 // will be cleared based on the parameter clear_perm.
a61af66fc99e Initial load duke parents: diff changeset	308 // There's a bit of subtlety in the clear() and invalidate()
a61af66fc99e Initial load duke parents: diff changeset	309 // methods that we exploit here and in invalidate_or_clear()
a61af66fc99e Initial load duke parents: diff changeset	310 // below to avoid missing cards at the fringes. If clear() or
a61af66fc99e Initial load duke parents: diff changeset	311 // invalidate() are changed in the future, this code should
a61af66fc99e Initial load duke parents: diff changeset	312 // be revisited. 20040107.ysr
a61af66fc99e Initial load duke parents: diff changeset	313 Generation* g = gen;
a61af66fc99e Initial load duke parents: diff changeset	314 for(Generation* prev_gen = gch->prev_gen(g);
a61af66fc99e Initial load duke parents: diff changeset	315 prev_gen != NULL;
a61af66fc99e Initial load duke parents: diff changeset	316 g = prev_gen, prev_gen = gch->prev_gen(g)) {
a61af66fc99e Initial load duke parents: diff changeset	317 MemRegion to_be_cleared_mr = g->prev_used_region();
a61af66fc99e Initial load duke parents: diff changeset	318 clear(to_be_cleared_mr);
a61af66fc99e Initial load duke parents: diff changeset	319 }
a61af66fc99e Initial load duke parents: diff changeset	320 // Clear perm gen cards if asked to do so.
a61af66fc99e Initial load duke parents: diff changeset	321 if (clear_perm) {
a61af66fc99e Initial load duke parents: diff changeset	322 MemRegion to_be_cleared_mr = gch->perm_gen()->prev_used_region();
a61af66fc99e Initial load duke parents: diff changeset	323 clear(to_be_cleared_mr);
a61af66fc99e Initial load duke parents: diff changeset	324 }
a61af66fc99e Initial load duke parents: diff changeset	325 }
a61af66fc99e Initial load duke parents: diff changeset	326
a61af66fc99e Initial load duke parents: diff changeset	327 void CardTableRS::invalidate_or_clear(Generation* gen, bool younger,
a61af66fc99e Initial load duke parents: diff changeset	328 bool perm) {
a61af66fc99e Initial load duke parents: diff changeset	329 GenCollectedHeap* gch = GenCollectedHeap::heap();
a61af66fc99e Initial load duke parents: diff changeset	330 // For each generation gen (and younger and/or perm)
a61af66fc99e Initial load duke parents: diff changeset	331 // invalidate the cards for the currently occupied part
a61af66fc99e Initial load duke parents: diff changeset	332 // of that generation and clear the cards for the
a61af66fc99e Initial load duke parents: diff changeset	333 // unoccupied part of the generation (if any, making use
a61af66fc99e Initial load duke parents: diff changeset	334 // of that generation's prev_used_region to determine that
a61af66fc99e Initial load duke parents: diff changeset	335 // region). No need to do anything for the youngest
a61af66fc99e Initial load duke parents: diff changeset	336 // generation. Also see note#20040107.ysr above.
a61af66fc99e Initial load duke parents: diff changeset	337 Generation* g = gen;
a61af66fc99e Initial load duke parents: diff changeset	338 for(Generation* prev_gen = gch->prev_gen(g); prev_gen != NULL;
a61af66fc99e Initial load duke parents: diff changeset	339 g = prev_gen, prev_gen = gch->prev_gen(g)) {
a61af66fc99e Initial load duke parents: diff changeset	340 MemRegion used_mr = g->used_region();
a61af66fc99e Initial load duke parents: diff changeset	341 MemRegion to_be_cleared_mr = g->prev_used_region().minus(used_mr);
a61af66fc99e Initial load duke parents: diff changeset	342 if (!to_be_cleared_mr.is_empty()) {
a61af66fc99e Initial load duke parents: diff changeset	343 clear(to_be_cleared_mr);
a61af66fc99e Initial load duke parents: diff changeset	344 }
a61af66fc99e Initial load duke parents: diff changeset	345 invalidate(used_mr);
a61af66fc99e Initial load duke parents: diff changeset	346 if (!younger) break;
a61af66fc99e Initial load duke parents: diff changeset	347 }
a61af66fc99e Initial load duke parents: diff changeset	348 // Clear perm gen cards if asked to do so.
a61af66fc99e Initial load duke parents: diff changeset	349 if (perm) {
a61af66fc99e Initial load duke parents: diff changeset	350 g = gch->perm_gen();
a61af66fc99e Initial load duke parents: diff changeset	351 MemRegion used_mr = g->used_region();
a61af66fc99e Initial load duke parents: diff changeset	352 MemRegion to_be_cleared_mr = g->prev_used_region().minus(used_mr);
a61af66fc99e Initial load duke parents: diff changeset	353 if (!to_be_cleared_mr.is_empty()) {
a61af66fc99e Initial load duke parents: diff changeset	354 clear(to_be_cleared_mr);
a61af66fc99e Initial load duke parents: diff changeset	355 }
a61af66fc99e Initial load duke parents: diff changeset	356 invalidate(used_mr);
a61af66fc99e Initial load duke parents: diff changeset	357 }
a61af66fc99e Initial load duke parents: diff changeset	358 }
a61af66fc99e Initial load duke parents: diff changeset	359
a61af66fc99e Initial load duke parents: diff changeset	360
a61af66fc99e Initial load duke parents: diff changeset	361 class VerifyCleanCardClosure: public OopClosure {
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	362 private:
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	363 HeapWord* _boundary;
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	364 HeapWord* _begin;
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	365 HeapWord* _end;
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	366 protected:
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	367 template <class T> void do_oop_work(T* p) {
0 a61af66fc99e Initial load duke parents: diff changeset	368 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	369 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	370 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	371 "[_begin, _end) = [" PTR_FORMAT "," PTR_FORMAT ")",
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	372 _begin, _end));
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	373 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	374 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	375 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	376 "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	377 (HeapWord*)obj, jp, _boundary));
0 a61af66fc99e Initial load duke parents: diff changeset	378 }
2428 5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	379
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	380 public:
ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	381 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	382 _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	383 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	384 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	385 b, begin));
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	386 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	387 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	388 begin, end));
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	389 }
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	390
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	391 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	392 virtual void do_oop(narrowOop* p) { VerifyCleanCardClosure::do_oop_work(p); }
0 a61af66fc99e Initial load duke parents: diff changeset	393 };
a61af66fc99e Initial load duke parents: diff changeset	394
a61af66fc99e Initial load duke parents: diff changeset	395 class VerifyCTSpaceClosure: public SpaceClosure {
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	396 private:
0 a61af66fc99e Initial load duke parents: diff changeset	397 CardTableRS* _ct;
a61af66fc99e Initial load duke parents: diff changeset	398 HeapWord* _boundary;
a61af66fc99e Initial load duke parents: diff changeset	399 public:
a61af66fc99e Initial load duke parents: diff changeset	400 VerifyCTSpaceClosure(CardTableRS* ct, HeapWord* boundary) :
a61af66fc99e Initial load duke parents: diff changeset	401 _ct(ct), _boundary(boundary) {}
113 ba764ed4b6f2 6420645: Create a vm that uses compressed oops for up to 32gb heapsizes coleenp parents: 6 diff changeset	402 virtual void do_space(Space* s) { _ct->verify_space(s, _boundary); }
0 a61af66fc99e Initial load duke parents: diff changeset	403 };
a61af66fc99e Initial load duke parents: diff changeset	404
a61af66fc99e Initial load duke parents: diff changeset	405 class VerifyCTGenClosure: public GenCollectedHeap::GenClosure {
a61af66fc99e Initial load duke parents: diff changeset	406 CardTableRS* _ct;
a61af66fc99e Initial load duke parents: diff changeset	407 public:
a61af66fc99e Initial load duke parents: diff changeset	408 VerifyCTGenClosure(CardTableRS* ct) : _ct(ct) {}
a61af66fc99e Initial load duke parents: diff changeset	409 void do_generation(Generation* gen) {
a61af66fc99e Initial load duke parents: diff changeset	410 // Skip the youngest generation.
a61af66fc99e Initial load duke parents: diff changeset	411 if (gen->level() == 0) return;
a61af66fc99e Initial load duke parents: diff changeset	412 // Normally, we're interested in pointers to younger generations.
a61af66fc99e Initial load duke parents: diff changeset	413 VerifyCTSpaceClosure blk(_ct, gen->reserved().start());
a61af66fc99e Initial load duke parents: diff changeset	414 gen->space_iterate(&blk, true);
a61af66fc99e Initial load duke parents: diff changeset	415 }
a61af66fc99e Initial load duke parents: diff changeset	416 };
a61af66fc99e Initial load duke parents: diff changeset	417
a61af66fc99e Initial load duke parents: diff changeset	418 void CardTableRS::verify_space(Space* s, HeapWord* gen_boundary) {
a61af66fc99e Initial load duke parents: diff changeset	419 // We don't need to do young-gen spaces.
a61af66fc99e Initial load duke parents: diff changeset	420 if (s->end() <= gen_boundary) return;
a61af66fc99e Initial load duke parents: diff changeset	421 MemRegion used = s->used_region();
a61af66fc99e Initial load duke parents: diff changeset	422
a61af66fc99e Initial load duke parents: diff changeset	423 jbyte* cur_entry = byte_for(used.start());
a61af66fc99e Initial load duke parents: diff changeset	424 jbyte* limit = byte_after(used.last());
a61af66fc99e Initial load duke parents: diff changeset	425 while (cur_entry < limit) {
a61af66fc99e Initial load duke parents: diff changeset	426 if (*cur_entry == CardTableModRefBS::clean_card) {
a61af66fc99e Initial load duke parents: diff changeset	427 jbyte* first_dirty = cur_entry+1;
a61af66fc99e Initial load duke parents: diff changeset	428 while (first_dirty < limit &&
a61af66fc99e Initial load duke parents: diff changeset	429 *first_dirty == CardTableModRefBS::clean_card) {
a61af66fc99e Initial load duke parents: diff changeset	430 first_dirty++;
a61af66fc99e Initial load duke parents: diff changeset	431 }
a61af66fc99e Initial load duke parents: diff changeset	432 // If the first object is a regular object, and it has a
a61af66fc99e Initial load duke parents: diff changeset	433 // young-to-old field, that would mark the previous card.
a61af66fc99e Initial load duke parents: diff changeset	434 HeapWord* boundary = addr_for(cur_entry);
a61af66fc99e Initial load duke parents: diff changeset	435 HeapWord* end = (first_dirty >= limit) ? used.end() : addr_for(first_dirty);
a61af66fc99e Initial load duke parents: diff changeset	436 HeapWord* boundary_block = s->block_start(boundary);
a61af66fc99e Initial load duke parents: diff changeset	437 HeapWord* begin = boundary; // Until proven otherwise.
a61af66fc99e Initial load duke parents: diff changeset	438 HeapWord* start_block = boundary_block; // Until proven otherwise.
a61af66fc99e Initial load duke parents: diff changeset	439 if (boundary_block < boundary) {
a61af66fc99e Initial load duke parents: diff changeset	440 if (s->block_is_obj(boundary_block) && s->obj_is_alive(boundary_block)) {
a61af66fc99e Initial load duke parents: diff changeset	441 oop boundary_obj = oop(boundary_block);
a61af66fc99e Initial load duke parents: diff changeset	442 if (!boundary_obj->is_objArray() &&
a61af66fc99e Initial load duke parents: diff changeset	443 !boundary_obj->is_typeArray()) {
a61af66fc99e Initial load duke parents: diff changeset	444 guarantee(cur_entry > byte_for(used.start()),
a61af66fc99e Initial load duke parents: diff changeset	445 "else boundary would be boundary_block");
a61af66fc99e Initial load duke parents: diff changeset	446 if (*byte_for(boundary_block) != CardTableModRefBS::clean_card) {
a61af66fc99e Initial load duke parents: diff changeset	447 begin = boundary_block + s->block_size(boundary_block);
a61af66fc99e Initial load duke parents: diff changeset	448 start_block = begin;
a61af66fc99e Initial load duke parents: diff changeset	449 }
a61af66fc99e Initial load duke parents: diff changeset	450 }
a61af66fc99e Initial load duke parents: diff changeset	451 }
a61af66fc99e Initial load duke parents: diff changeset	452 }
a61af66fc99e Initial load duke parents: diff changeset	453 // 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	454 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	455 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	456 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	457 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	458 if (s->block_is_obj(cur) && s->obj_is_alive(cur)) {
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	459 oop(cur)->oop_iterate(&verify_blk, mr);
5134fa1cfe63 7029036: Card-table verification hangs with all framework collectors, except G1, even before the first GC ysr parents: 1972 diff changeset	460 }
0 a61af66fc99e Initial load duke parents: diff changeset	461 }
a61af66fc99e Initial load duke parents: diff changeset	462 }
a61af66fc99e Initial load duke parents: diff changeset	463 cur_entry = first_dirty;
a61af66fc99e Initial load duke parents: diff changeset	464 } else {
a61af66fc99e Initial load duke parents: diff changeset	465 // We'd normally expect that cur_youngergen_and_prev_nonclean_card
a61af66fc99e Initial load duke parents: diff changeset	466 // is a transient value, that cannot be in the card table
a61af66fc99e Initial load duke parents: diff changeset	467 // except during GC, and thus assert that:
a61af66fc99e Initial load duke parents: diff changeset	468 // guarantee(*cur_entry != cur_youngergen_and_prev_nonclean_card,
a61af66fc99e Initial load duke parents: diff changeset	469 // "Illegal CT value");
a61af66fc99e Initial load duke parents: diff changeset	470 // That however, need not hold, as will become clear in the
a61af66fc99e Initial load duke parents: diff changeset	471 // following...
a61af66fc99e Initial load duke parents: diff changeset	472
a61af66fc99e Initial load duke parents: diff changeset	473 // We'd normally expect that if we are in the parallel case,
a61af66fc99e Initial load duke parents: diff changeset	474 // we can't have left a prev value (which would be different
a61af66fc99e Initial load duke parents: diff changeset	475 // from the current value) in the card table, and so we'd like to
a61af66fc99e Initial load duke parents: diff changeset	476 // assert that:
a61af66fc99e Initial load duke parents: diff changeset	477 // guarantee(cur_youngergen_card_val() == youngergen_card
a61af66fc99e Initial load duke parents: diff changeset	478 // \|\| !is_prev_youngergen_card_val(*cur_entry),
a61af66fc99e Initial load duke parents: diff changeset	479 // "Illegal CT value");
a61af66fc99e Initial load duke parents: diff changeset	480 // That, however, may not hold occasionally, because of
a61af66fc99e Initial load duke parents: diff changeset	481 // CMS or MSC in the old gen. To wit, consider the
a61af66fc99e Initial load duke parents: diff changeset	482 // following two simple illustrative scenarios:
a61af66fc99e Initial load duke parents: diff changeset	483 // (a) CMS: Consider the case where a large object L
a61af66fc99e Initial load duke parents: diff changeset	484 // spanning several cards is allocated in the old
a61af66fc99e Initial load duke parents: diff changeset	485 // gen, and has a young gen reference stored in it, dirtying
a61af66fc99e Initial load duke parents: diff changeset	486 // some interior cards. A young collection scans the card,
a61af66fc99e Initial load duke parents: diff changeset	487 // finds a young ref and installs a youngergenP_n value.
a61af66fc99e Initial load duke parents: diff changeset	488 // L then goes dead. Now a CMS collection starts,
a61af66fc99e Initial load duke parents: diff changeset	489 // finds L dead and sweeps it up. Assume that L is
a61af66fc99e Initial load duke parents: diff changeset	490 // abutting _unallocated_blk, so _unallocated_blk is
a61af66fc99e Initial load duke parents: diff changeset	491 // adjusted down to (below) L. Assume further that
a61af66fc99e Initial load duke parents: diff changeset	492 // no young collection intervenes during this CMS cycle.
a61af66fc99e Initial load duke parents: diff changeset	493 // The next young gen cycle will not get to look at this
a61af66fc99e Initial load duke parents: diff changeset	494 // youngergenP_n card since it lies in the unoccupied
a61af66fc99e Initial load duke parents: diff changeset	495 // part of the space.
a61af66fc99e Initial load duke parents: diff changeset	496 // Some young collections later the blocks on this
a61af66fc99e Initial load duke parents: diff changeset	497 // card can be re-allocated either due to direct allocation
a61af66fc99e Initial load duke parents: diff changeset	498 // or due to absorbing promotions. At this time, the
a61af66fc99e Initial load duke parents: diff changeset	499 // before-gc verification will fail the above assert.
a61af66fc99e Initial load duke parents: diff changeset	500 // (b) MSC: In this case, an object L with a young reference
a61af66fc99e Initial load duke parents: diff changeset	501 // is on a card that (therefore) holds a youngergen_n value.
a61af66fc99e Initial load duke parents: diff changeset	502 // Suppose also that L lies towards the end of the used
a61af66fc99e Initial load duke parents: diff changeset	503 // the used space before GC. An MSC collection
a61af66fc99e Initial load duke parents: diff changeset	504 // occurs that compacts to such an extent that this
a61af66fc99e Initial load duke parents: diff changeset	505 // card is no longer in the occupied part of the space.
a61af66fc99e Initial load duke parents: diff changeset	506 // Since current code in MSC does not always clear cards
a61af66fc99e Initial load duke parents: diff changeset	507 // in the unused part of old gen, this stale youngergen_n
a61af66fc99e Initial load duke parents: diff changeset	508 // value is left behind and can later be covered by
a61af66fc99e Initial load duke parents: diff changeset	509 // an object when promotion or direct allocation
a61af66fc99e Initial load duke parents: diff changeset	510 // re-allocates that part of the heap.
a61af66fc99e Initial load duke parents: diff changeset	511 //
a61af66fc99e Initial load duke parents: diff changeset	512 // Fortunately, the presence of such stale card values is
a61af66fc99e Initial load duke parents: diff changeset	513 // "only" a minor annoyance in that subsequent young collections
a61af66fc99e Initial load duke parents: diff changeset	514 // might needlessly scan such cards, but would still never corrupt
a61af66fc99e Initial load duke parents: diff changeset	515 // the heap as a result. However, it's likely not to be a significant
a61af66fc99e Initial load duke parents: diff changeset	516 // performance inhibitor in practice. For instance,
a61af66fc99e Initial load duke parents: diff changeset	517 // some recent measurements with unoccupied cards eagerly cleared
a61af66fc99e Initial load duke parents: diff changeset	518 // out to maintain this invariant, showed next to no
a61af66fc99e Initial load duke parents: diff changeset	519 // change in young collection times; of course one can construct
a61af66fc99e Initial load duke parents: diff changeset	520 // degenerate examples where the cost can be significant.)
a61af66fc99e Initial load duke parents: diff changeset	521 // Note, in particular, that if the "stale" card is modified
a61af66fc99e Initial load duke parents: diff changeset	522 // after re-allocation, it would be dirty, not "stale". Thus,
a61af66fc99e Initial load duke parents: diff changeset	523 // we can never have a younger ref in such a card and it is
a61af66fc99e Initial load duke parents: diff changeset	524 // safe not to scan that card in any collection. [As we see
a61af66fc99e Initial load duke parents: diff changeset	525 // below, we do some unnecessary scanning
a61af66fc99e Initial load duke parents: diff changeset	526 // in some cases in the current parallel scanning algorithm.]
a61af66fc99e Initial load duke parents: diff changeset	527 //
a61af66fc99e Initial load duke parents: diff changeset	528 // The main point below is that the parallel card scanning code
a61af66fc99e Initial load duke parents: diff changeset	529 // deals correctly with these stale card values. There are two main
a61af66fc99e Initial load duke parents: diff changeset	530 // cases to consider where we have a stale "younger gen" value and a
a61af66fc99e Initial load duke parents: diff changeset	531 // "derivative" case to consider, where we have a stale
a61af66fc99e Initial load duke parents: diff changeset	532 // "cur_younger_gen_and_prev_non_clean" value, as will become
a61af66fc99e Initial load duke parents: diff changeset	533 // apparent in the case analysis below.
a61af66fc99e Initial load duke parents: diff changeset	534 // o Case 1. If the stale value corresponds to a younger_gen_n
a61af66fc99e Initial load duke parents: diff changeset	535 // value other than the cur_younger_gen value then the code
a61af66fc99e Initial load duke parents: diff changeset	536 // treats this as being tantamount to a prev_younger_gen
a61af66fc99e Initial load duke parents: diff changeset	537 // card. This means that the card may be unnecessarily scanned.
a61af66fc99e Initial load duke parents: diff changeset	538 // There are two sub-cases to consider:
a61af66fc99e Initial load duke parents: diff changeset	539 // o Case 1a. Let us say that the card is in the occupied part
a61af66fc99e Initial load duke parents: diff changeset	540 // of the generation at the time the collection begins. In
a61af66fc99e Initial load duke parents: diff changeset	541 // that case the card will be either cleared when it is scanned
a61af66fc99e Initial load duke parents: diff changeset	542 // for young pointers, or will be set to cur_younger_gen as a
a61af66fc99e Initial load duke parents: diff changeset	543 // result of promotion. (We have elided the normal case where
a61af66fc99e Initial load duke parents: diff changeset	544 // the scanning thread and the promoting thread interleave
a61af66fc99e Initial load duke parents: diff changeset	545 // possibly resulting in a transient
a61af66fc99e Initial load duke parents: diff changeset	546 // cur_younger_gen_and_prev_non_clean value before settling
a61af66fc99e Initial load duke parents: diff changeset	547 // to cur_younger_gen. [End Case 1a.]
a61af66fc99e Initial load duke parents: diff changeset	548 // o Case 1b. Consider now the case when the card is in the unoccupied
a61af66fc99e Initial load duke parents: diff changeset	549 // part of the space which becomes occupied because of promotions
a61af66fc99e Initial load duke parents: diff changeset	550 // into it during the current young GC. In this case the card
a61af66fc99e Initial load duke parents: diff changeset	551 // will never be scanned for young references. The current
a61af66fc99e Initial load duke parents: diff changeset	552 // code will set the card value to either
a61af66fc99e Initial load duke parents: diff changeset	553 // cur_younger_gen_and_prev_non_clean or leave
a61af66fc99e Initial load duke parents: diff changeset	554 // it with its stale value -- because the promotions didn't
a61af66fc99e Initial load duke parents: diff changeset	555 // result in any younger refs on that card. Of these two
a61af66fc99e Initial load duke parents: diff changeset	556 // cases, the latter will be covered in Case 1a during
a61af66fc99e Initial load duke parents: diff changeset	557 // a subsequent scan. To deal with the former case, we need
a61af66fc99e Initial load duke parents: diff changeset	558 // to further consider how we deal with a stale value of
a61af66fc99e Initial load duke parents: diff changeset	559 // cur_younger_gen_and_prev_non_clean in our case analysis
a61af66fc99e Initial load duke parents: diff changeset	560 // below. This we do in Case 3 below. [End Case 1b]
a61af66fc99e Initial load duke parents: diff changeset	561 // [End Case 1]
a61af66fc99e Initial load duke parents: diff changeset	562 // o Case 2. If the stale value corresponds to cur_younger_gen being
a61af66fc99e Initial load duke parents: diff changeset	563 // a value not necessarily written by a current promotion, the
a61af66fc99e Initial load duke parents: diff changeset	564 // card will not be scanned by the younger refs scanning code.
a61af66fc99e Initial load duke parents: diff changeset	565 // (This is OK since as we argued above such cards cannot contain
a61af66fc99e Initial load duke parents: diff changeset	566 // any younger refs.) The result is that this value will be
a61af66fc99e Initial load duke parents: diff changeset	567 // treated as a prev_younger_gen value in a subsequent collection,
a61af66fc99e Initial load duke parents: diff changeset	568 // which is addressed in Case 1 above. [End Case 2]
a61af66fc99e Initial load duke parents: diff changeset	569 // o Case 3. We here consider the "derivative" case from Case 1b. above
a61af66fc99e Initial load duke parents: diff changeset	570 // because of which we may find a stale
a61af66fc99e Initial load duke parents: diff changeset	571 // cur_younger_gen_and_prev_non_clean card value in the table.
a61af66fc99e Initial load duke parents: diff changeset	572 // Once again, as in Case 1, we consider two subcases, depending
a61af66fc99e Initial load duke parents: diff changeset	573 // on whether the card lies in the occupied or unoccupied part
a61af66fc99e Initial load duke parents: diff changeset	574 // of the space at the start of the young collection.
a61af66fc99e Initial load duke parents: diff changeset	575 // o Case 3a. Let us say the card is in the occupied part of
a61af66fc99e Initial load duke parents: diff changeset	576 // the old gen at the start of the young collection. In that
a61af66fc99e Initial load duke parents: diff changeset	577 // case, the card will be scanned by the younger refs scanning
a61af66fc99e Initial load duke parents: diff changeset	578 // code which will set it to cur_younger_gen. In a subsequent
a61af66fc99e Initial load duke parents: diff changeset	579 // scan, the card will be considered again and get its final
a61af66fc99e Initial load duke parents: diff changeset	580 // correct value. [End Case 3a]
a61af66fc99e Initial load duke parents: diff changeset	581 // o Case 3b. Now consider the case where the card is in the
a61af66fc99e Initial load duke parents: diff changeset	582 // unoccupied part of the old gen, and is occupied as a result
a61af66fc99e Initial load duke parents: diff changeset	583 // of promotions during thus young gc. In that case,
a61af66fc99e Initial load duke parents: diff changeset	584 // the card will not be scanned for younger refs. The presence
a61af66fc99e Initial load duke parents: diff changeset	585 // of newly promoted objects on the card will then result in
a61af66fc99e Initial load duke parents: diff changeset	586 // its keeping the value cur_younger_gen_and_prev_non_clean
a61af66fc99e Initial load duke parents: diff changeset	587 // value, which we have dealt with in Case 3 here. [End Case 3b]
a61af66fc99e Initial load duke parents: diff changeset	588 // [End Case 3]
a61af66fc99e Initial load duke parents: diff changeset	589 //
a61af66fc99e Initial load duke parents: diff changeset	590 // (Please refer to the code in the helper class
a61af66fc99e Initial load duke parents: diff changeset	591 // ClearNonCleanCardWrapper and in CardTableModRefBS for details.)
a61af66fc99e Initial load duke parents: diff changeset	592 //
a61af66fc99e Initial load duke parents: diff changeset	593 // The informal arguments above can be tightened into a formal
a61af66fc99e Initial load duke parents: diff changeset	594 // correctness proof and it behooves us to write up such a proof,
a61af66fc99e Initial load duke parents: diff changeset	595 // or to use model checking to prove that there are no lingering
a61af66fc99e Initial load duke parents: diff changeset	596 // concerns.
a61af66fc99e Initial load duke parents: diff changeset	597 //
a61af66fc99e Initial load duke parents: diff changeset	598 // Clearly because of Case 3b one cannot bound the time for
a61af66fc99e Initial load duke parents: diff changeset	599 // which a card will retain what we have called a "stale" value.
a61af66fc99e Initial load duke parents: diff changeset	600 // However, one can obtain a Loose upper bound on the redundant
a61af66fc99e Initial load duke parents: diff changeset	601 // work as a result of such stale values. Note first that any
a61af66fc99e Initial load duke parents: diff changeset	602 // time a stale card lies in the occupied part of the space at
a61af66fc99e Initial load duke parents: diff changeset	603 // the start of the collection, it is scanned by younger refs
a61af66fc99e Initial load duke parents: diff changeset	604 // code and we can define a rank function on card values that
a61af66fc99e Initial load duke parents: diff changeset	605 // declines when this is so. Note also that when a card does not
a61af66fc99e Initial load duke parents: diff changeset	606 // lie in the occupied part of the space at the beginning of a
a61af66fc99e Initial load duke parents: diff changeset	607 // young collection, its rank can either decline or stay unchanged.
a61af66fc99e Initial load duke parents: diff changeset	608 // In this case, no extra work is done in terms of redundant
a61af66fc99e Initial load duke parents: diff changeset	609 // younger refs scanning of that card.
a61af66fc99e Initial load duke parents: diff changeset	610 // Then, the case analysis above reveals that, in the worst case,
a61af66fc99e Initial load duke parents: diff changeset	611 // any such stale card will be scanned unnecessarily at most twice.
a61af66fc99e Initial load duke parents: diff changeset	612 //
a61af66fc99e Initial load duke parents: diff changeset	613 // It is nonethelss advisable to try and get rid of some of this
a61af66fc99e Initial load duke parents: diff changeset	614 // redundant work in a subsequent (low priority) re-design of
a61af66fc99e Initial load duke parents: diff changeset	615 // the card-scanning code, if only to simplify the underlying
a61af66fc99e Initial load duke parents: diff changeset	616 // state machine analysis/proof. ysr 1/28/2002. XXX
a61af66fc99e Initial load duke parents: diff changeset	617 cur_entry++;
a61af66fc99e Initial load duke parents: diff changeset	618 }
a61af66fc99e Initial load duke parents: diff changeset	619 }
a61af66fc99e Initial load duke parents: diff changeset	620 }
a61af66fc99e Initial load duke parents: diff changeset	621
a61af66fc99e Initial load duke parents: diff changeset	622 void CardTableRS::verify() {
a61af66fc99e Initial load duke parents: diff changeset	623 // At present, we only know how to verify the card table RS for
a61af66fc99e Initial load duke parents: diff changeset	624 // generational heaps.
a61af66fc99e Initial load duke parents: diff changeset	625 VerifyCTGenClosure blk(this);
a61af66fc99e Initial load duke parents: diff changeset	626 CollectedHeap* ch = Universe::heap();
a61af66fc99e Initial load duke parents: diff changeset	627 // We will do the perm-gen portion of the card table, too.
a61af66fc99e Initial load duke parents: diff changeset	628 Generation* pg = SharedHeap::heap()->perm_gen();
a61af66fc99e Initial load duke parents: diff changeset	629 HeapWord* pg_boundary = pg->reserved().start();
a61af66fc99e Initial load duke parents: diff changeset	630
a61af66fc99e Initial load duke parents: diff changeset	631 if (ch->kind() == CollectedHeap::GenCollectedHeap) {
a61af66fc99e Initial load duke parents: diff changeset	632 GenCollectedHeap::heap()->generation_iterate(&blk, false);
342 37f87013dfd8 6711316: Open source the Garbage-First garbage collector ysr parents: 113 diff changeset	633 _ct_bs->verify();
0 a61af66fc99e Initial load duke parents: diff changeset	634
a61af66fc99e Initial load duke parents: diff changeset	635 // If the old gen collections also collect perm, then we are only
a61af66fc99e Initial load duke parents: diff changeset	636 // interested in perm-to-young pointers, not perm-to-old pointers.
a61af66fc99e Initial load duke parents: diff changeset	637 GenCollectedHeap* gch = GenCollectedHeap::heap();
a61af66fc99e Initial load duke parents: diff changeset	638 CollectorPolicy* cp = gch->collector_policy();
a61af66fc99e Initial load duke parents: diff changeset	639 if (cp->is_mark_sweep_policy() \|\| cp->is_concurrent_mark_sweep_policy()) {
a61af66fc99e Initial load duke parents: diff changeset	640 pg_boundary = gch->get_gen(1)->reserved().start();
a61af66fc99e Initial load duke parents: diff changeset	641 }
a61af66fc99e Initial load duke parents: diff changeset	642 }
a61af66fc99e Initial load duke parents: diff changeset	643 VerifyCTSpaceClosure perm_space_blk(this, pg_boundary);
a61af66fc99e Initial load duke parents: diff changeset	644 SharedHeap::heap()->perm_gen()->space_iterate(&perm_space_blk, true);
a61af66fc99e Initial load duke parents: diff changeset	645 }
a61af66fc99e Initial load duke parents: diff changeset	646
a61af66fc99e Initial load duke parents: diff changeset	647
6 73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	648 void CardTableRS::verify_aligned_region_empty(MemRegion mr) {
0 a61af66fc99e Initial load duke parents: diff changeset	649 if (!mr.is_empty()) {
a61af66fc99e Initial load duke parents: diff changeset	650 jbyte* cur_entry = byte_for(mr.start());
a61af66fc99e Initial load duke parents: diff changeset	651 jbyte* limit = byte_after(mr.last());
6 73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	652 // The region mr may not start on a card boundary so
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	653 // the first card may reflect a write to the space
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	654 // just prior to mr.
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	655 if (!is_aligned(mr.start())) {
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	656 cur_entry++;
73e96e5c30df 6624765: Guarantee failure "Unexpected dirty card found" jmasa parents: 0 diff changeset	657 }
0 a61af66fc99e Initial load duke parents: diff changeset	658 for (;cur_entry < limit; cur_entry++) {
a61af66fc99e Initial load duke parents: diff changeset	659 guarantee(*cur_entry == CardTableModRefBS::clean_card,
a61af66fc99e Initial load duke parents: diff changeset	660 "Unexpected dirty card found");
a61af66fc99e Initial load duke parents: diff changeset	661 }
a61af66fc99e Initial load duke parents: diff changeset	662 }
a61af66fc99e Initial load duke parents: diff changeset	663 }

Mercurial > hg > truffle

annotate src/share/vm/memory/cardTableRS.cpp @ 5939:c7a555a9449a