Mon, 26 Jan 2009 12:47:21 -0800
6786503: Overflow list performance can be improved
Summary: Avoid overflow list walk in CMS & ParNew when it is unnecessary. Fix a couple of correctness issues, including a C-heap leak, in ParNew at the intersection of promotion failure, work queue overflow and object array chunking. Add stress testing option and related assertion checking.
Reviewed-by: jmasa
1 /*
2 * Copyright 2000-2008 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
25 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and
26 // enumerate ref fields that have been modified (since the last
27 // enumeration), using a card table.
29 class OopClosure;
30 class Generation;
32 class ModRefBarrierSet: public BarrierSet {
33 public:
35 ModRefBarrierSet() { _kind = BarrierSet::ModRef; }
37 bool is_a(BarrierSet::Name bsn) {
38 return bsn == BarrierSet::ModRef;
39 }
41 // Barriers only on ref writes.
42 bool has_read_ref_barrier() { return false; }
43 bool has_read_prim_barrier() { return false; }
44 bool has_write_ref_barrier() { return true; }
45 bool has_write_prim_barrier() { return false; }
47 bool read_ref_needs_barrier(void* field) { return false; }
48 bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; }
49 virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;
50 bool write_prim_needs_barrier(HeapWord* field, size_t bytes,
51 juint val1, juint val2) { return false; }
53 void write_prim_field(oop obj, size_t offset, size_t bytes,
54 juint val1, juint val2) {}
56 void read_ref_field(void* field) {}
57 void read_prim_field(HeapWord* field, size_t bytes) {}
58 protected:
59 virtual void write_ref_field_work(void* field, oop new_val) = 0;
60 public:
61 void write_prim_field(HeapWord* field, size_t bytes,
62 juint val1, juint val2) {}
64 bool has_read_ref_array_opt() { return false; }
65 bool has_read_prim_array_opt() { return false; }
66 bool has_write_prim_array_opt() { return false; }
68 bool has_read_region_opt() { return false; }
71 // These operations should assert false unless the correponding operation
72 // above returns true.
73 void read_ref_array(MemRegion mr) {
74 assert(false, "can't call");
75 }
76 void read_prim_array(MemRegion mr) {
77 assert(false, "can't call");
78 }
79 void write_prim_array(MemRegion mr) {
80 assert(false, "can't call");
81 }
82 void read_region(MemRegion mr) {
83 assert(false, "can't call");
84 }
86 // Invoke "cl->do_oop" on (the address of) every possibly-modifed
87 // reference field in objects in "sp". If "clear" is "true", the oops
88 // are no longer considered possibly modified after application of the
89 // closure. If' "before_save_marks" is true, oops in objects allocated
90 // after the last call to "save_marks" on "sp" will not be considered.
91 virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,
92 bool clear = false,
93 bool before_save_marks = false) = 0;
95 // Causes all refs in "mr" to be assumed to be modified. If "whole_heap"
96 // is true, the caller asserts that the entire heap is being invalidated,
97 // which may admit an optimized implementation for some barriers.
98 virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0;
100 // The caller guarantees that "mr" contains no references. (Perhaps it's
101 // objects have been moved elsewhere.)
102 virtual void clear(MemRegion mr) = 0;
104 // Pass along the argument to the superclass.
105 ModRefBarrierSet(int max_covered_regions) :
106 BarrierSet(max_covered_regions) {}
108 #ifndef PRODUCT
109 // Verifies that the given region contains no modified references.
110 virtual void verify_clean_region(MemRegion mr) = 0;
111 #endif
113 };